Retailers' Reference Guide

Retailers’ Reference Guide Diamonds, Gemstones, Pearls and Precious Metals Preface

Welcome to the Retailers’ Reference Guide: We have created this Guide to meet a need that Diamonds, Gemstones, Pearls and Precious Metals. has been highlighted by jewellery retailers around This ground-breaking piece of work is the result the world. Namely an accessible reference guide of the exceptional efforts of a large number of that allows jewellery retailers at all levels to members in all the CIBJO Commissions. By coming benefit from the enormous knowledge contained together in this manner we are confident that this within CIBJO. guide will assist jewellery retailing globally. I truly believe that this Guide will provide an Research has shown that empowering staff with excellent resource that will support and drive the vital knowledge about the products they sales growth for all types of jewellery retailer sell leads to sustainable sales growth. Jewellery and will become crucial to making CIBJO member consumers all around the world are looking for businesses more successful. greater information about the products we sell. Wishing you all future success. At the Marketing and Education Commission we are committed to providing jewellery retailers with the tools to sell more effectively. We can develop the most inspiring jewellery products in the world but if the retailing does not live up to the product we Jonathan Kendall President will fail to compete with other luxury products. Marketing and Education Commission, CIBJO

CIBJO Retailers’ Reference Guide May 2010 How to use the Retailers’ Reference Guide

This Guide is designed to provide retailers with a better Retailers’ Reference Guide contributors understanding of the fundamentals of Diamonds, Gemstones, This guide is the result of a large number of In addition many thanks for their help Pearls and Precious Metals. individuals’ exceptionally hard work and the and support to: co-operation of all CIBJO’s Sector III and Precious • Donna Baker, GIA President Metal Commissions. It has two sections: • Jean-Pierre Chalain , Swiss Gemmological The CIBJO Marketing and Education Commission Institute, SSEF • Key facts guides that act as a quick reference guide. would especially like to thank: • Andrew Cody, ICA President • Martin Coeroli, President CIBJO We recommend that these are printed and laminated • Shigeru Akamatsu of Mikimoto & Co. Pearl Commission for the text and image development to provide a simple reference on the shop floor. • James Courage, Platinum Guild International of the Pearl chapter • Dona Dirlam, GIA Library and her staff • Michael Allchin of The Birmingham Assay • Full chapters, covering Diamonds, Gemstones, Pearls • Raitu Galenon, CIBJO Pearl Commission Office for all his help and support on • Héja Garcia-Guillerminet, Laboratoire and Precious Metals in greater detail, that deliver the Precious Metals chapter Français de Gemmologie • Jonathan Kendall of De Beers Group a basic reference guide for jewellery retailers. • Matt Graydon, World Gold Council as the project sponsor • Gérard Grospiron, Grospiron Jewellers • André Marais of De Beers Group • Doug Hucker, AGTA CEO for project co-ordination and production • Michael Krzemnicki, Swiss Gemmological • Roland Naftule, CIBJO President Sector III Institute, SSEF the project Gem Materials co-ordinator • Harry Levy, Levy Gems • Jon C. Phillips of BHP Billiton for all of his • Thomas Lind, Lind Granat help and support on the Diamond chapter • Richard Peplow, Peplow Jewellers • Ken Scarratt of GIA for the text and image • Emmanuel Piat, Piat & Co. development of the Pearl chapter Coloured gemstone section written by the Gemmological Institute of America, Carlsbad, California. • Neils Ruddy Hansen All rights reserved. • Robert Weldon of the GIA for the text and • Nick Sturman, Bahrain Directorate of image development of the Gemstone chapter All rights reserved. No part of this Guide may be reproduced, republished, amended, translated or changed, Precious Metals & Gemstone Testing including all images included in the Guide, without the express written permission of CIBJO or its authorised agents. Permission to republish, reproduce and/or translate of this Guide is limited to CIBJO member organisations only, • Hanco Zwann, NEL and is subject to written agreements between CIBJO and/or its agents and the CIBJO membership organisation.

CIBJO Retailers’ Reference Guide May 2010 Contents

Key facts: Reference guides:

Diamonds Diamonds Gemstones Pearls Precious metals Gemstones 3 Introduction to diamonds 3 Alexandrite and other chrysoberyls 3 Introduction – 3 Introduction Cultured pearls 4 Properties of diamond 6 Amethyst types of pearls 4 Common Control Mark Precious metals 5 Classifying diamonds 8 Aquamarine 5 Natural pearls 5 Gold into types 10 Other beryls 8 Cultured pearls 8 Silver 6 From rough to polished 13 Citrine 9 Pearl culturing and 9 Platinum 8 The 4 Cs 15 Emerald the molluscs 10 Palladium 9 Carat 18 Feldspar group 11 Quality of the 10 Cut 22 Garnet group cultured pearl 15 Colour 26 Jade 14 Treatment of a pearl 19 Clarity 29 Kunzite or cultured pearl 23 Certification of diamonds 31 Lapis lazuli 24 Synthetics 33 Opal 25 Diamond simulants 38 Organic gems 27 Treatments 42 Peridot 44 Unusual quartzes and chalcedony 50 Ruby 53 Sapphire 56 Spinel 58 Tanzanite 60 Topaz 63 Tourmaline 66 Turquoise 69 Zircon

CIBJO Retailers’ Reference Guide May 2010 Key facts Retailers’ Reference Guide

KEY FACTS Key facts: Diamonds

Cut Common cutting styles • Diamonds are worn by people as potent symbols of love, devotion, pride, wealth and Cut is the shape and cutting style Asscher Cushion Emerald Heart Marquise power. of a diamond. The cut, polish and proportions of a diamond will • At least 13 factors affect determine its appearance. The shape diamond value, including of a diamond is a matter of personal fluorescence, table taste, with the round brilliant cut the percentage, symmetry and most popular. Other shapes are the other crucial details. asscher, cushion, emerald, heart, pear, • The most important factors marquise, oval, princess and trilliant. when determining the quality of a diamond are known as the 4 Cs. These are the diamond’s Carat Pear Princess Oval Round Trilliant carat weight, its cut, its colour and its clarity. Carat is often mistakenly used to • The key thing to note is that refer to a diamond’s size, but it is no one C is more significant actually a measure of weight. One than another. A particular carat (equivalent to 200 milligrams) combination of the 4 Cs can can be divided into 100 “points”. be chosen to suit a particular A 0.75 carat diamond may also budget, occasion, design or be described as a 75-point or jewellery piece. ¾ carat diamond.

Larger diamonds are found less Guide to approximate carat size frequently in nature, so they can command a significantly higher price. For instance, a one carat diamond will cost more than two ½ carat diamonds

of equal colour, clarity and cut. 2 CTS 1.5 CTS 1.25 CTS 1 CTS 0.75 CTS 0.50 CTS 0.25 CTS 0.10 CTS 75 points 50 points 25 points 10 points

All rights reserved. No part of this Guide may be reproduced, republished, amended, translated or changed, including all images included in the Guide, without the express written permission of CIBJO or its authorised agents. Permission to republish, reproduce and/or translate of this Guide is limited CIBJO Retailers’ Reference Guide May 2010 to CIBJO member organisations only, and is subject to written agreements between CIBJO and/or its agents and the CIBJO membership organisation. Colour Clarity KEY FACTS

Diamonds are found in almost every colour expert under controlled lighting conditions Every diamond is unique. Nature ensures The number, type, colour, size and position of the rainbow, but white-coloured diamonds and compared against a master set for that each diamond is as individual as the of these inclusions can affect the value of a remain the most popular. There are more accuracy. Those at the upper end of the person who wears it. Naturally-occurring diamond. However, many can only be seen by than 20 subtle grades of colour, identified in scale will be more expensive, as they are features – known as inclusions – provide a experts using a 10-power magnification loupe. alphabetical order from D-Z. Variations are so rarer. However, they are difficult to discern special fingerprint within the stone. Usually Even with the loupe, the tiniest inclusions can slight that colours must be graded by an with the naked eye. invisible to the naked eye, these tiny marks be very difficult to find. are minerals or fractures which appeared while Flawless diamonds are rarer and thus, more the diamonds were forming in the earth. expensive, but small inclusions do not affect Colour Grading scales* the beauty or the brilliance of a diamond. GIA CIBJO / IDC Scan. D.N. AGS GIA

D Exceptional White+ 0 D River E Exceptional White 1 E

Colourless F Rare White+ Top 2 F Wesselton G Rare White 3 G

H White Wesselton 4 H Clarity Grading scales*

Near I Top Crystal I GIA CIBJO / IDC Scan. D.N. AGS Key: colourless Slightly Tinted White 5 J Crystal J LC Loupe clean K 6 K FL FL 0

Tinted White Top Cape LC F Flawless L L

Faint Faint IF IF IF Internally flawless

yellow 7 M M 1 VVS Very, very slightly VVS VVS VVS N N 1 1 1 included (very, very

O 8 O small inclusions) VVS2 VVS2 VVS2 2 P P VS Very slightly included

yellow VS VS VS 3 light Very Q Q 1 1 1 (very small inclusions) R R SI Slightly included VS VS VS 4 9 2 2 2 S Tinted colour Cape S (small inclusions) SI SI SI 5 T T 1 1 1 I Included U U P Piqué SI2 SI2 SI2 6 V V I P P 7,8 W W 1 1 1 10 Light yellow X X I2 P2 P2 8,9 Y Y I P P 9,10 There are other grading systems used Z Z 3 3 3 * by laboratories around the world.

CIBJO Retailers’ Reference Guide May 2010 KEY FACTS Key facts: Gemstones

Gemstone properties: chemical, optical and physical • Most gems are natural, inorganic minerals that have a specific chemical composition and Properties in a gemstone species are • Birefringence – The strength a characteristic structure. a series of generally repeatable traits, of double refraction measured which help distinguish gem varieties by the difference between the • Some gem minerals, such as from one another, and gem species highest and the lowest refractive opals or natural glass do not have and groups from one another: indices. Birefringence is only an orderly crystal structure; these measurable in a doubly refractive gems are amorphous. • Chemical formula – gemstone. The chemical makeup • Some gems are organic, meaning of a gemstone. • Specific Gravity – The ratio they come from plants or of the weight of a material animals, such as: pearls, amber, • Refractive Index – An optical to that of an equal volume of coral and ivory. measure of the extent to which water at 4˚ Celsius. light is bent as it enters or • To be called a “gem” any of the leaves a gemstone at an angle • Mohs Hardness Scale – above-mentioned materials must other than perpendicular to the Developed by Frederich Mohs embody three important traits: surface. It is expressed as the in 1822, the Mohs scale is beauty, rarity and relative ratio of the speed of light in air a comparative scale of the durability. to its speed in the gemstone. hardness of different minerals.

Natural gemstones covered in the CIBJO Retailers’ Reference Guide

Alexandrite Amethyst Aquamarine Other beryls Citrine Emerald The feldspar The garnet Jade Kunzite Lapis lazuli Opal and other group group chrysoberyls

Gem materials are occasionally Additionally, different gem There are many products in the Many important natural gemstones For more information about treated to improve their treatments require different care gem and jewelry business that look (such as ruby, sapphire, spinel, and CIBJO standards and rules appearance. The aim of treatments requirements. Because treatments like gems but are not, and they emerald and other beryls) have regarding treatments, artificial is to strengthen colour, improve affect the value of gemstones, are sometimes called “simulants.” man-made counterparts that are and imitation products, or clarity, accentuate phenomena, there is a need to inform and/ These products are not described manufactured in a laboratory. synthetic stones, please improve luster and/or improve or disclose how a gem has been in the Retailers’ Reference Guide, Such materials are called synthetic download a free pdf copy durability of the stone. treated. Information about gem but CIBJO describes such products because they have virtually the of CIBJO’s Coloured Gemstone treatments should occur at every as follows: same chemical, physical and Bluebook here: www.cibjo.org Treatments include: dyeing or step of the buying and selling optical characteristics as their coating gems; heating to improve Artificial stones – artificial process from wholesale to retail, natural counterparts. While colour and clarity; lead glass, crystalline products with no known and ultimately to members of the synthetic products are not covered wax or resin impregnations of a natural counterparts. buying public. in this Retailers’ Reference Guide, gem’s fractures pits or fissures; Imitations – artificial products that it is important to follow CIBJO’s lattice diffusion of gemstones and For specific information about imitate the appearance of precious nomenclature when discussing, irradiation or bleaching. In some how to do this, see panel (right). stones, gemstones, ornamental selling or buying such materials. cases, a combination of treatments stones or organic substances may take place to achieve the without having their chemical treater’s desired result. composition and/or their physical properties and/or their structure.

Natural gemstones covered in the CIBJO Retailers’ Reference Guide

Organic gems Peridot Unusual Ruby Sapphire Spinel Tanzanite Topaz Tourmaline Turquoise Zircon quartzes and chalcedony

CIBJO Retailers’ Reference Guide May 2010

KEY FACTS Key facts: Cultured pearls

Types of pearls Varieties of cultured pearls

• Natural pearls are pearls Akoya cultured pearls are Black-lipped cultured pearls are accidentally formed in the cultured in Japan, China and cultured mainly in French Polynesia interior of a mollusc without Vietnam using Akoya oysters using Black-lipped pearl oyster human intervention. (Pinctada fucata (martensii)). (Pinctada margaritifera). They appear Compared with other “pearl in the markets under the trade term • Cultured pearls are formed oysters”, the Akoya oyster is of “Tahiti cultured pearl”. Common within molluscs with human rather small; hence the size size is over 10mm, but recently intervention. This intervention of pearl produced is less than smaller-sized pearls have been should only instigate the 10mm. The most popular sizes increasing. In addition to common formation of the nacre – the are 6 and 7mm natural grey or black colour, there substance normally produced is a wide variety of shades from by the various “pearl oysters” purplish to greenish. for the formation of both the shell and pearls.

• Imitation pearls are artificial products not formed in molluscs Silver / Gold-lipped cultured pearls Freshwater cultured pearls are but manufactured by imitating are cultured in Australia, Indonesia cultured in China, Japan and United the appearance, colour and and Philippines using Silver /Gold- States. Most are non-beaded other features of natural or lipped pearl oysters (Pinctada cultured pearl. Chinese pearls cultured pearls. This is irrespective maxima). Australia produces large cultured with “Triangle mussel” of whether physical or chemical sized high quality pearls over 10mm (Hyriopsis cumingii) are dominant. properties are the same as while in Indonesia smaller sized By improving the culturing natural and/or cultured pearls. pearls of below 10mm are also technique, large, round and produced. The Philippines produce smooth-surfaced cultured pearls many golden pearls using Gold- are produced. There is a wide variety lipped oyster. of colours the three usual being white, orange and purple.

Size Lustre Any action by man that alters Sizes of cultured pearls are measured in millimeters (mm). Lustre is defined by the quality the appearance of a pearl or Size range is dependent on pearl producing oyster species. of the reflected light. A lustrous cultured pearl is considered to • Akoya cultured pearl: 2-10mm pearl has a strong bright and be a treatment. sharp reflection. A low lustre • Silver/Gold-lipped and Black-lipped cultured pearl: 8-16mm • Treatments that do not need pearl is not bright and its to be declared: drilling, • Freshwater cultured pearl: 2-13mm. reflection is dull. The lustre of polishing, buffing, peeling a pearl may be closely related and cleaning. to the homogeneity, light Shape transmittance and thickness • Treatments that must be Perfectly round is highly valued. Shapes are divided into: round, of the nacre. declared: bleaching, coating, semi-round, oval, drop, button, and semi-baroque. cutting, dyeing (tinting), filling, heating, irradiation, oiling, waxing and working.

Nacre thickness Colour Degree of nacre coating of the beaded cultured pearls. It has some A pearl’s colour contains three • Silver/Gold-lipped cultured More information impact of their colour, luster and durability. X-rays are used to basic components, hue, tone and pearl: Silver, silver pink, pink, measure nacre thickness and assist in observing nacre quality. saturation. Colour characteristics grey, cream, yellow, golden, differ according to the mollusc white. For more information about species. • Black-lipped cultured pearl: CIBJO standards and rules • Akoya cultured pearl: Black, green, brown, blue, regarding treatments, please Pink, green pink, silver pink, peacock, red. download a free pdf copy of cream pink, white, green, CIBJO’s Pearl Bluebook here: • Freshwater cultured pearl: cream, gold. www.cibjo.org Three basic colours (orange, purple, white)

Surface condition The surface of a cultured pearl is examined in terms of the number, size, kind and location of the imperfections. In evaluating the surface of cultured pearls, imperfections are taken into account – whether the pearl has a clean surface, one spot or many spots.

CIBJO Retailers’ Reference Guide May 2010 KEY FACTS Key facts: Precious metals

Gold Silver Platinum Palladium • A precious metal is a rare metallic chemical element which is of high economic value.

• The best known precious metals are silver, gold and the platinum group.

• Assaying is the process of measuring the metallurgical content of gold, silver or Gold is a rare metallic element. Silver is a soft, white, lustrous Platinum is one of the rarest Palladium is one of the platinum platinum in precious metals. Its chemical symbol, Au, is short transition metal and is used precious metals, found in only group metals but is considered There are numerous methods for the Latin word for gold, in currency, ornaments and a few places – principally South a precious metal in its own which can be used and the “Aurum”, which literally means jewellery. It has the highest Africa and Russia. Platinum will right. It is naturally white, which choice usually depends on how “Glowing Dawn”. electrical and thermal not fade or tarnish – keeping means there is no need for accurate the measurement conductivity for a metal. its natural white colour forever. rhodium plating. needs to be as well as the cost. Pure gold has a bright yellow Most platinum jewellery is colour and is one of only two Sterling silver is an alloy of It is more precious than silver • Assaying will usually be carried either 90% or 95% pure, does coloured metal elements, the silver containing 92.5% pure and lighter than platinum out by an assay office in order not need rhodium plating and other being copper. All other silver and 7.5% other metals, (nearly half the weight) so larger to determine if the purity is being hypoallergenic will not metals are silver or grey. usually copper. Britannia silver is necklaces and bracelets can equal or better than that cause an allergic reaction. The an alternative hallmark-quality be made capable of bearing claimed by the maker. Once White golds are gold alloys that density of platinum gives it a standard containing 95.8% bigger gemstones with no gain an assay office has determined look white rather than yellow. heft, its ductile nature allows silver, often used to make silver in overall weight. For the same the purity, they will stamp The white colour is achieved by craftsman to create the most tableware and wrought plate. reason palladium is considered a hallmark on the item to careful choice of the alloying intricate pieces, and its physical to be a good choice for earrings certify it. metals, which bleach the deep properties ensure that precious although unlike platinum it is yellow of pure gold. gemstones are held securely. not hypoallergenic.

A hallmark, is a mark or series of marks struck on items made of precious metals – platinum, gold, silver and in some nations, palladium. Hallmarks are applied by an assay office and they guarantee a certain purity or fineness of the metal.

As a pre-requisite to official hallmarking, the maker or sponsor of a piece of jeweller must provide a responsibility mark and claim of fitness. The hallmarking by an assay office is to confirm this claim.

Hallmarking systems differ from country to country. The Vienna Convention of 1973 was an attempt to standardise the legislation on the inspection of precious metals and to facilitate international trade.

Articles which are assayed and found to be in conformity by the qualifying office of a signatory country receive a mark, known as the Common Control Mark.

The countries that have signed up to the Vienna Convention have done so to facilitate international trade in precious metals. It does not mean they have compulsory hallmarking in their domestic market. Some have compulsory hallmarking, such as the Czech Republic, Ireland, Netherlands, Poland, Switzerland and UK, while others have a voluntary system allowing jewellery to be sold either with or without hallmarks, for example Austria, Denmark, Finland and Sweden.

CIBJO Retailers’ Reference Guide May 2010 Diamonds Retailers’ Reference Guide Diamonds Contents: Diamonds

3 Introduction to diamonds 15 Colour The information in the following chapter was provided by the CIBJO Diamond Commission with images provided 4 Properties of diamond 16 Colour grading scales by DeBeers and HRD. 17 Fancy colours 5 Classifying diamonds into types 18 Cause of colour in diamonds 6 From rough to polished 18 Ultraviolet flourescence 7 Processes 19 Clarity 8 The 4 Cs 20 Examples of inclusions 9 Carat 21 Grading terms

10 Cut 22 Grading scales 11 Common cutting styles 23 Certification of diamonds 13 Styles of faceting 24 Synthetics 14 Diamond Cut Quality Grades 25 Diamond simulants

27 Treatments

All rights reserved. No part of this Guide may be reproduced, republished, amended, translated or changed, including all images included in the Guide, without the express written permission of CIBJO or its authorised agents. Permission to republish, reproduce and/or translate of this Guide is limited to CIBJO member organisations only, and is subject to written agreements between CIBJO and/or its agents and the CIBJO membership organisation.

2 CIBJO Retailers’ Reference Guide May 2010 Diamonds Introduction to diamonds

Natural diamonds can be as old as There are two main types of diamond Diamonds are mined in over 20 countries 3.3 billion years and have always been deposits: around the world and they can be found a gemstone associated with mystery, in remote deserts, frozen tundra and even • Primary deposits: These are myth and magic. From the earliest ocean beds. However, main production diamondiferous pipes which are bodies civilisations, diamonds have been comes from Botswana, Russia, South of solidified Kimberlite or Lamproite. prized possessions. Their rarity, and the Africa, Canada and Australia. It is interesting to note that diamonds immense skill required to release their do not form in these volcanic bodies Diamond mining methods include extraordinary brilliance, makes them but are merely transported to the open-cast mining, alluvial, underground unlike any other jewel. Worn by people surface in them. mining and marine mining. In general as potent symbols of love, devotion, terms, only about 20% of the volumes pride, wealth and power – they convey • Secondary deposits: These are of all diamonds mined are good enough a variety of emotions. deposits that contain diamonds which quality to be used for jewellery. Every have weather worn out of the host pipe in the world produces different Origin of diamonds body and then travelled some distance qualities and quantities but generally from their original source. For example, Thought to have been created in even a profitable mine removes over one the diamonds that are now found in the earth’s upper mantle 150-200 tonne of host rock to produce one carat Namibia have travelled over 1,500 kilometres below the earth’s surface and of gem quality diamonds. kilometres from their original source under tremendous heat and pressure, in southern Africa. diamonds were carried to the planet’s surface by volcanic forces so violent we know nothing like it today. They then had to endure nature’s wrath over countless millennia.

3 CIBJO Retailers’ Reference Guide May 2010 Diamonds Properties of diamond

Diamond is a unique mineral. It possesses Toughness: Diamond is not a tough stone. certain physical and optical properties Toughness is the resistance to breaking, Mohs scale that make it special not only in jewellery chipping or cracking when impacted with but also for industrial applications. It is a blow. Diamond can chip and sometimes Diamond 10 a crystalline material composed of pure if hit just right will actually cleave along Corundum 9 carbon. It grows in the cubic crystal a flat planar surface. Most chips on a system with a refractive index of 2.417, diamond will occur around the girdle or Topaz 8 specific gravity of 3.52, dispersion of 0.044 edge. Jade is actually a lot tougher than Quartz 7 and hardness of 10 on the Mohs scale diamond but not anywhere near as hard. (see right). Orthoclase feldspar 6 Stability: Diamond will burn at around 750oC which can be reached with a Apatite 5 Durability jeweller’s torch. A diamond that has Fluorite 4 Durability is a gemstone’s ability to just had the surface burned will be hazy withstand wear, heat, impact and looking and will need to be re-polished Calcite 3 chemicals. Durability is broken down into to remove the burnt surface. The more Gypsum 2 three categories hardness, toughness dangerous situation for a diamond is and stability. thermal shock or the sudden change in Talc 1 extreme temperatures. Diamond can Hardness: Hardness of a material is fracture or have inclusions extended from related to its resistance to scratching thermal shock. The Mohs scale was developed in 1822 by Friedrich Mohs, or its response to a sharp point being and has been used to assess hardness for over 150 years. dragged across its surface. Diamond There are ten minerals in this series. Diamond is the hardest is generally recognised as the hardest mineral, it is at the top of the scale. However, this is not a substance known to man. The hardness linear scale but merely an order as every mineral in the scale of a diamond varies slightly in different will scratch all minerals below it. For example, there is very directions. Polishers rely on directional little difference in hardness between talc and gypsum, but hardness in diamond in order to use an enormous difference between corundum and diamond. diamond to polish a diamond.

4 CIBJO Retailers’ Reference Guide May 2010 Diamonds Classifying diamonds into types

Diamonds can be classified into two basic types and then subdivided into seven sub-categories. The two basic types are Type I and Type II. Type I diamonds contain appreciable levels of nitrogen as an impurity incorporated within the (crystal) atomic structure. These are known as impurities, as opposed to “inclusions”, which are merely enclosed within the stone but not actually incorporated into its molecular structure. Type II diamonds contain virtually no nitrogen. However, there is a continuum of nitrogen concentrations from zero to over 1%, so a stone may show “mixed” or intermediate characteristics. Type II diamonds are the type of diamond that can typically be treated by HPHT (see page 29) to change their body colour.

5 CIBJO Retailers’ Reference Guide May 2010 Diamonds From rough to polished

When extracted from the ground, diamonds often display characteristic crystal surfaces with high lustre or a frosted appearance. It is the skill and experience of a diamond cutter that will bring the beauty out of a stone. The images to the right show just a few of the varied shapes a rough diamond comes in. In trying to get the best quality and biggest size from a rough diamond, the cutter must strike a balance between loss of weight and the ideal proportions for beauty and economic profit.

6 CIBJO Retailers’ Reference Guide May 2010 Diamonds From rough to polished

Processes

A variety of processes or steps are required • Sawing – is the main choice for • Bruting – shaping the original outline • Polishing – or finishing is the to take a rough diamond and bring it dividing rough diamonds. There is of the rough crystal and to prepare sequence in the process of putting through to a polished stone suitable for traditional sawing with a very thin the girdle. on the final polish, raising the lustre use in jewellery. Basically these are: blade and diamond paste and there (reflectivity) to the maximum level • Blocking and brillianteering – faceting is also laser sawing. Laser sawing, for a diamond. • Design and marking – entails accurate of the rough diamond. Blocking is the while more expensive, is the method marking and estimating optimal initial step in faceting. It determines of choice for tricky rough and outcomes from the rough crystal. the shape, weight and symmetry. more expensive crystals because Brillianteering is the act of placing the • Cleaving – is splitting a diamond along of the lower risk of damage, and final facets on the blocked diamond. its natural crystal grain. This is rarely the possibility to saw in any crystal done today as it is risky although it direction. can be faster and cheaper.

Marking a rough diamond Cleaving a rough diamond Bruting a diamond Polishing a diamond

7 CIBJO Retailers’ Reference Guide May 2010 Diamonds The 4 Cs

Around the world customers, diamontaires In basic terms the best in each of the 4 Cs and retailers discuss diamonds in terms of will yield the highest value diamond. The the 4 Cs: Carat, Cut, Colour and Clarity. final value of a diamond is like a perfectly The 4 Cs provide a precise and systematic balanced old fashioned weight scale, with language that enables everyone to value on one side and the 4 Cs on the compare and value diamonds. other. Changing any one of the 4 Cs on one side of the scale means you must A diamond’s value is based on the change the value in order to balance the combination of all of the 4 Cs. Each of the scale again. For instance if your customer 4 Cs has a range of possible outcomes and decides they want to buy a bigger only rarely will you find a diamond that diamond than they were originally offered is graded as the most desirable in each then they will have to pay more or they of the 4 Cs. Rarity and value are directly can choose to lower one or more of the related, so the rarer the characteristic remaining 3 Cs to balance the scale. the more valuable the diamond. It is important to remember that while each diamond can be described by its own special combination of the 4 Cs, its observed beauty is usually much more than just a list of characteristics.

8 CIBJO Retailers’ Reference Guide May 2010 Diamonds Carat

Carat is often used to refer to a Diamonds are weighed to the Do not confuse the term carat with Larger diamonds are found less diamond’s size, but it is actually a metric thousandth of a carat (0.001 carats) karat. As you have read the term carat frequently in nature, therefore they measure of weight. It is often abbreviated then for final sale or certification is a metric weight for gemstones, while are rarer and so they can command a as “ct”. One carat (equivalent to 200 rounded to the hundredth of a carat. karat is a measure of the purity or significantly higher price compared to milligrams) can also be divided into 100 Each country has specific regulations fineness of gold. (see Precious Metals equal quality smaller diamonds. For “points”. The “points” do not refer to for rounding up or down to the next section of Retailers’ Reference Guide). instance, a one carat diamond will cost facet junctions, only to the diamond’s hundredth of a carat. Many countries more than two ½ carat diamonds of total weight. A 0.75 carat diamond may only allow rounding up to the next equal colour, clarity and cut. also be described as a ¾ carat diamond or carat when the last thousandth decimal 75 points. The term “point” or “pointers” place is a 9, then 1.299 carats could be is only used for diamonds weighing less rounded up to 1.30 carats. than 1 carat. For anything over a carat then the rules change a little. A 1.08-ct diamond may be called either a “one point ‘O’ eight carat” diamond or a “one point zero eight carat” diamond. In the wholesale trade there is also a term of a “grainer”. A one grainer diamond equals approximately one quarter of a carat so then a five grainer is approximately 2 CTS 1.5 CTS 1.25 CTS 1 CTS 0.75 CTS 0.50 CTS 0.25 CTS 0.10 CTS a 1.25 carat diamond. 75 points 50 points 25 points 10 points

Guide to approximate carat size

9 CIBJO Retailers’ Reference Guide May 2010 Diamonds Cut

Cut is the C that is most affected by Light performance and ideal Shapes the skill and expertise of the markers, The concept of an ideal cut diamond is The most common shapes in the market cutters and polishers. The proper cut not new as diamond manufacturers have today are asscher, cushion, round, emerald, will ultimately unlock the true beauty been striving for perfection since diamond heart, marquise, pear, princess, oval, of a rough diamond and also reveal its cutting began. The goal is to achieve the round and trilliant (see following pages). maximum economic potential. perfect balance of brilliance, fire and There are also many modified shapes A well cut diamond is a special balance scintillation in a polished diamond or the and novelty cuts some of which are between three important factors – “ideal” cut. patented. More likely though you will hear brilliance, dispersion and scintillation. of trademarked, copyrighted or “branded Experts to this day do not agree on one Brilliance is the return of white light to cuts” which have been developed by single set of cutting parameters for the the viewer’s eyes from the internal and individual companies. A branded cut will ultimate title of “ideal” for all but they do external surfaces of a diamond. Dispersion have something unusual or a parameter agree that there is a range of parameters or as it is more commonly known “fire” are that is different than the standard cut. that do produce the most pleasing looking the flashes of spectral colours that come Shapes other than round are referred to diamond. With the current availability of from a diamond. Scintillation is the sparkle as fancy shapes. electronic light performance measuring or flashes of light you see as the diamond equipment and scientific analysis the data or light source moves. collected has become astounding. The cut of diamond at the most basic level crown One point all experts agree on is that refers to a diamond’s shape outline such cutting to these exacting standards does as round, pear, heart, etc. It can also refer girdle lose the most amount from the rough and to the style of faceting such as brilliant, that the cutting costs are higher. So as step cut or mixed cut or it can also refer you can imagine you should expect to pay to a combination of both shape and pavilion more for an “ideal” cut of any brand. faceting like emerald cut or princess. On a higher level a professional diamond grader will refer to a diamond’s cut it terms of proportions, symmetry and finish. Parts of a cut diamond

10 CIBJO Retailers’ Reference Guide May 2010 Diamonds Cut

Common cutting styles Asscher Cushion Emerald Heart Marquise

11 CIBJO Retailers’ Reference Guide May 2010 Diamonds Cut

Common cutting styles Pear Princess Oval Round Trilliant

12 CIBJO Retailers’ Reference Guide May 2010 Diamonds Cut

Styles of Faceting

A brilliant cut is a general term used for Mixed cut diamonds have a combination diamonds that are cut with triangular or of both step cut and brilliant cut facets. kite shaped facets. A facet is a flat planar The two different styles of faceting are surface cut and polished on the surface of arranged so one is either on the top which the diamond. For brilliant cut the facets is known as the crown or on the bottom start at a central point and radiate towards which is known as the pavilion of the the edge or girdle. The most popular of diamond. all the diamonds is a round brilliant with 57 or 58 facets which in smaller sizes Proportions, symmetry and finish may be referred to as a full cut. A single Proportions – refer to the dimensions and cut diamond has 17 or 18 facets and is angles of the main parts of the diamond. typically under 0.03 carats in weight. Symmetry – is the exactness of the A step cut is a term used for a diamond balance and symmetry of the diamond‘s with long narrow trapezoidal facets shape and faceting. usually arranged in three rows parallel to the girdle. A good example of this is the Finish – this is sometimes referred to as emerald cut diamond with a rectangular polish, it is a measure of the quality of the shape outline and bevelled corners. diamond’s polished surfaces and edges. A baguette cut is step cut as well. It can be straight or tapered with fewer parallel rows than the emerald cut and sharp corners. It is often smaller in size and used en masse or as side stones.

13 CIBJO Retailers’ Reference Guide May 2010 Diamonds Cut

Diamond Cut Quality Grades

The rating of a diamond’s overall cut Background Other considerations in a diamonds overall grade or make is one of the more complex cut quality grade are a combination of the A polished diamond’s beauty lies in its assessments in the diamond trade. diamond’s design, proportions and finish complex relationship with light: how light Previously overall make was an individual (polish and symmetry). strikes the surface, how much enters the assessment of proportions and finish diamond, and how, and in what form light (polish and symmetry). returns to your eye. Now many laboratories issue overall cut The face up appearance or light grades on their reports which are based performance is a display of three on a combination of several factors not attributes. just by measured parameters, but also visual observations. The GIA and AGS both 1. Brightness is the result of all internal have overall cut grades available on their and external reflections of white light. reports. Both use a deductive system in 2. Fire which results when white light is which a diamonds cumulative cut grade dispersed into its spectral colours. is determined by a combination of the diamond’s proportions, polish and symmetry. 3. Scintillation describes the sparkle of light you see in a diamond, and the The most commonly used cut quality overall pattern of bright and dark areas grading system is for standard round when you look at a diamond face-up. brilliant cut diamonds in D-Z colours only and 0.15cts and larger. Proportions are a measured parameter that are an important determinate in a The GIA uses word terms Excellent, Very diamonds cut quality grade but they are good, Good, Fair and Poor. The AGS uses not the sole determinate. Proportions do the number system from 0 to10 with 0 affect a diamonds light performance, which being the best. All systems suggest a final in turn affects its beauty and overall appeal. grade based on their own research that Diamonds with better proportions optimize indicates the degree of acceptability to the interaction with light, and generally the consumer. have better brilliance, fire, and scintillation.

14 CIBJO Retailers’ Reference Guide May 2010 Diamonds Colour

As we talk about a diamond’s colour Colourless and near colourless The most prevalent systems use a letter For the tinted colour category (GIA M-Z) we can talk about two different grade, a word term or a number to the diamonds are accurately described by There are several colour grading systems aspects. When most people talk about designate the final colour. The stones colour terms like Yellowish to Yellow and being used in the jewellery trade today. a diamond’s colour they are actually are viewed with controlled lighting, Brownish to Brown. Those at the upper All of the systems work on the same referring to colourless or near colourless upside down in a colour tray because end of the scale (closer to D) will be more principle of comparing an unknown diamonds. Colourless or near colourless face up the true body colour may be expensive, as they are rarer. sample to a known sample or master diamonds remain the most available masked by the cut. stone. In conjunction with human graders There are other grading systems used by and the most popular with consumers. most large laboratories are now using The most widely used of all the laboratories around the world. However, what most consumers are scientific colour grading instruments to existing systems is the one used by the unaware of is that diamonds are found determine the colour grade of a diamond. Gemmological Institute of America (GIA). in almost every colour. Diamonds occur Colour is considered a range from It has over 20 subtle grades of colour, – albeit rarely – in red, blue, green and all colourless to light yellow or brown. identified in alphabetical order from D-Z. other colours of the rainbow (see Fancy The American Gem Society uses a number colours, page 17). system from 0.00 to 10.00. CIBJO uses eight word terms ranging from Exceptional White to Tinted Colour.

15 CIBJO Retailers’ Reference Guide May 2010 Diamonds Colour

Colour grading scales

GIA CIBJO / IDC 1 Scan. D.N. 2 AGS GIA

D Exceptional White+ 0 D River E Exceptional White 1 E

Colourless F Rare White+ Top 2 F G Rare White Wesselton 3 G

H White Wesselton 4 H

Near I Top Crystal I

colourless Slightly Tinted White 5 J Crystal J

K 6 K Tinted White Top Cape L L

Faint Faint 7 yellow M M

N N

O 8 O Visual colour grading of polished diamonds

P P yellow

Very light Q Q

R R 9 S Tinted colour Cape S

T T 1 CIBJO Rules (1991) permit combining the U U Exceptional White and Rare White divisions V V into one level each for stones under 0.47ct. W W 10 Light yellow 2 Traditional terms; Scan.D.N. (1979) X X also allows use of two alternate sets Y Y of descriptive terms. Z Z

16 CIBJO Retailers’ Reference Guide May 2010 Diamonds Colour fancy colours

The D-Z colour grades mainly apply to The term “fancy” covers a wide range of yellow and brown-tinged stones. If these colours: the range within fancy yellow is colours are intense (Z+) in a diamond, approximately three times greater than they are referred to as “fancy-coloured”. the range of colours between D and Z on For other colours such as blue, pink, red, the normal colour scale. Therefore, some green, etc., the colour does not need modifications were made to the fancy to be intense to be considered fancy as colour descriptions in 1995. The term these colours are rare and highly prized. “fancy” was expanded to include Fancy Light, Fancy, Fancy Intense, Fancy Dark, For fancy colour diamonds, the market Fancy Deep and Fancy Vivid. In colours value is determined almost exclusively other than yellow and brown, the grading by the intensity of the colour, which can system also has the following categories: in some diamonds significantly outweigh Faint, Very Light and Light. the effects of lower clarity and of a poor make.

17 CIBJO Retailers’ Reference Guide May 2010 Diamonds Colour

Cause of colour in diamonds Ultraviolet fluorescence A diamond crystal is colourless. Any Diamonds sometimes show a fluorescent colour found in a diamond is caused reaction or glow under a UV source of by impurities within its crystal lattice light. Diamonds can fluoresce many structure or damage to the lattice. colours but the most typical colour is blue. Fluorescence is graded on a scale Impurities within a diamond absorb light of none to strong. and the result is a coloured stone. When small amounts of impurities, such as Strong and very strong fluorescence may nitrogen, boron or hydrogen, on an atomic have an impact on the perceived colour scale, enter the lattice of carbon atoms, of a diamond. A diamond with strong or replacing some of them, the colour of very strong fluorescence may show an the stone may dramatically change. For oily appearance under daylight (or UV) instance, nitrogen impurities will result conditions. This will make a yellowish in yellow hues and boron impurities will stone appear to be more colourless than result in blue hues in a diamond. it really is. Therefore, fluorescence can improve the perceived colour in stones In some brown, pink or reddish colour with a yellow tinge. For higher colour hues internal lattice defects can be the stones (D-I) very strong fluorescence can cause. The natural green colour seen in affect the value negatively as the oily diamonds is in most cases the result of a look is a distraction. natural irradiation by radioactive minerals or due to radioactive ground waters in secondary deposits. Such natural diamonds are completely safe to wear. A black diamond of natural colouration owes its colour to the presence of black inclusions (usually sulphides) or graphitised fractures.

18 CIBJO Retailers’ Reference Guide May 2010 Diamonds Clarity

Clarity is one of the Cs that your customer Blemishes – include surface features like Size – The larger the inclusion the lower Number – Generally, the more inclusions is most familiar with. It is tangible and scratches and nicks. Sometimes these can the grade. Very large inclusions can there are, the lower the clarity grade. This visual so besides carat it is the easiest be easily removed by re-polishing. be dangerous to the durability of the is carefully considered in tandem with the one of the 4Cs to show. Clarity grading diamond as well. size, nature and location of the inclusions. Inclusions – include internal features like has a certain level of subjectivity to it as feathers and crystals (see images on page Nature – Internal clarity characteristics Clarity characteristics may be thought of no two stones are alike. A professional 19). These have an impact on the final generally affect the grade more than as a negative but they can be a positive will view the diamond at 10 power (10x) clarity grade and are not easily removed. external characteristics. Highly contrasted too. Most natural diamond inclusions magnification in a controlled environment inclusions are less desirable. help gemologists separate diamond from and arrive at a conclusion of the clarity Clarity grading is the art and science its imitators and they can also help in grade based on systematically examining of assessing the visibility and effects Location – Inclusions centrally located, identifying the same diamond later on the diamond for clarity characteristics. of a diamond’s blemishes and inclusions. especially under the table, are more visible if a plot of the inclusions was done. A professional will view each diamond for than those near the edge or under a bezel Clarity characteristics include a wide range clarity grading with four simple words in facet. A cleavage near the surface is more of features but they are generally broken his mind, size, nature, location and number. dangerous than one that is completely down into two basic categories. The grader will then assess the overall enclosed in the stone. impact and visibility of both the inclusions and blemishes. Each of these is considered carefully in combination with each other before arriving at the final clarity grade.

19 CIBJO Retailers’ Reference Guide May 2010 Diamonds Clarity

Examples of Inclusions

An example of a crystal inclusion An example of a feather inclusion

20 CIBJO Retailers’ Reference Guide May 2010 Diamonds Clarity

Grading Terms

Clarity grading is a visual process, FL – Flawless – Free from all inclusions or SI1 – Slightly Included 1– Noticeable Note: There exists in the jewellery trade however there are several systems that blemishes at 10x magnification. inclusions that are easy to see at 10x. an SI3 grade. It is intended to bridge use word terms to help us arrive at the large gap in value and grading IF – Internally Flawless – No inclusions SI – Slightly Included 2 – Noticeable the appropriate clarity grade. The most 2 between SI and I . It is not used by visible at 10x but will have insignificant inclusions that are very easy to see at 2 1 widely used of all the existing systems GIA, AGS or CIBJO. surface blemishes only. 10x. They may also be barely eye visible is the one used by the Gemological in larger stones or in smaller stones Institute of America (GIA). It has 11 VVS – Very Very Slightly Included 1 – 1 through the pavilion. clarity grades; they are from Flawless to Minute inclusions that are extremely

Included 3. The American Gem Society difficult to see at 10x. I1 – Included 1 – Obvious inclusions at uses a number system from 0 to 10. 10x and visible to the unaided eye. VVS – Very Very Slightly Included 2 – CIBJO uses word terms Loupe Clean to 2 Minute inclusions that are very difficult I – Included 2 – Obvious inclusions at 10x Piqué 3. Those at the upper end of the 2 to see at 10x. and easily visible to the unaided eye and scale (closer to flawless) will be more they may pose a durability issue. expensive, as they are rarer. For more VS1 – Very Slightly Included 1 – Minor grading terms details see the following inclusions that are difficult to see face up I 3 – Included 3 – Prominent inclusions page. at 10x. that are extremely easy to see with the unaided eye and usually will affect the Find below basic word terms for the GIA VS – Very Slightly Included 2 – Minor 2 durability. Clarity grades. These are meant as a very inclusions that are somewhat easy to see general guideline only. face up at 10x.

21 CIBJO Retailers’ Reference Guide May 2010 Diamonds Clarity

Grading scales

GIA CIBJO / IDC Scan. D.N. AGS

FL FL 0 LC IF IF 1

VVS1 VVS1 VVS1

VVS2 VVS2 VVS2 2

VS1 VS1 VS1 3

VS2 VS2 VS2 4

SI1 SI1 SI1 5 Key: LC Loupe clean VS Very slightly included SI2 SI2 SI2 6 F Flawless (very small inclusions)

I1 P1 P1 7,8 IF Internally flawless SI Slightly included (small inclusions) I2 P2 P2 8,9 VVS Very, very slightly included (very, very small inclusions) I Included I3 P3 P3 9,10 P Piqué

22 CIBJO Retailers’ Reference Guide May 2010 Diamonds Certification of diamonds

Diamond grading certificates have Large, very low quality stones and smaller become a very large part of the jewellery stones are usually not certificated because business. This is because the average of the cost involved, although even this DIAMOND GRADING REPORT consumer is unable to evaluate a is changing. Prices for a certificate vary Shape and Cutting Style...... Round Brilliant Measurements 5.60-5.67x3.51mm diamond’s characteristics. depending upon its type, the issuing Weight 1.05 carat

laboratory and the weight of the stone. Proportions Legitimate certificates play a very Depth 61.8% Table 56% important role in accurately recording Each retailer will have to establish Girdle MEDIUM, SLIGHTLY FACETED the nature and quality of a diamond which certificates are trustworthy Culet Medium Finish which in turn gives the consumer and reliable for their own purposes. Polish Excellent confidence in what they are purchasing. Remember the certificate you use to Symmetry Excellent Clarity Grade Internally Flawless Not every diamond, however, has a sell a diamond will reflect on your Colour Grade F Flourescence None certificate and not all certificates are store too. Consult your local jewellers Comments: equal. Whether a stone gets certified is association or CIBJO for who has the a matter of value and sometimes and ethics and level of professionalism internal company policy. that you need for your store.

Colour D E F G H I J K L M N O P Q R S T U V W X Y Z scale X

Clarity Flawless/ VVS1 VVS2 VS1 VS2 SI1 SI2 I1 I2 I3 scale Internally flawless X

A sample diamond grading report

23 CIBJO Retailers’ Reference Guide May 2010 Diamonds Synthetics

“Synthetic diamonds” refers to diamonds HPHT CVD that are manufactured by man. Synthetic HPHT stands for High Pressure High Scientists can also produce diamond diamonds are not a new product as Temperature diamond synthesis and is from the plasma phase using a technique they have been around since the 1950s a complex and costly procedure. In this called Chemical Vapour Deposition (CVD) in industrial quality and in commercial well-established technique, graphite or thin film synthesis. This method when jewellery quantities and qualities since or diamond powder is mixed with a used for gem size synthetic diamonds the 1990s. They have essentially the solvent-catalyst such as nickel or cobalt is a very complex and costly procedure same chemical composition, physical and and subjected to high pressure (60kb) as well. This was first achieved in optical properties. Synthetic diamonds and high pressure (1400˚C) for periods 1952, and the method is now capable should not be confused with other of hours or days. Most of these synthetic of producing both single-crystal and diamond imitations and simulants (see diamonds are produced for the jewellery polycrystalline diamond. These jewellery- Diamond simulants section, page 24). market in hues of yellow, orange, pink, quality synthetic diamonds are generally Some synthetic diamonds provide black and blue. HPHT synthetics now brownish upon completion and then gemologists with easy to understand account for most of the synthetic HPHT treated in order to attain a tell-tale signs of their non-natural origin. diamonds on the market. colourless to near colourless synthetic However most synthetic diamonds diamond. Colourless CVD synthetic will require sophisticated laboratory diamonds are more difficult to identify equipment in order to positively identify compared to most HPHT synthetic their origin. There are two types of diamonds, however they are also not jewellery quality synthetic diamonds currently available in larger quantities in on the market, HPHT and CVD. the jewellery market.

24 CIBJO Retailers’ Reference Guide May 2010 Diamonds Diamond simulants

Diamonds are rare and valuable gems. A diamond simulant does not have Colourless topaz Colourless zircon This has inspired people to search for, the same chemical, physical, or optical Natural colourless topaz was used for This is a natural gemstone and has a or create, materials that look and feel like properties so can not be called synthetic many years as a diamond substitute. pleasant fire and brilliance. Because of diamond, but which are less expensive. diamonds (see page 23). In recent The inclusions found in topaz differ from its high double refraction, it can have In order to be a plausible substitute for years, important advances have been those seen in diamond. Rough crystals a ‘fuzzy’ appearance; you can see the diamond, a simulant needs to have a high made in the production of simulants. have often misled people into thinking double images of the facets as you look brilliance, a high degree of hardness and It used to be easy to identify simulants they were diamonds, because they through the stone. Zircon also pits at the an almost total lack of colour. because they lacked a diamond’s special are relatively dense and hard, and are same facet junctions very easily. Do not fire and brilliance but, in some cases, A diamond simulant is any product sometimes found in alluvial deposits. confuse zircon with Cubic Zirconia (CZ) identification is now becoming more produced to resemble a diamond. These Colourless topaz does not have enough (see page 25). challenging. products may be similar in appearance to dispersion to be truly convincing as a diamond, but have different chemical or a diamond simulant, although it can Natural and synthetic Colourless glass physical properties. Synthetic Moissanite make a bright stone. white sapphire and Cubic Zirconia are examples of Since Egyptian times, glass has been These have been occasionally used as products which may be sold as simulants. used as a simulant. The best imitations a diamond simulant. Natural colourless are made from glass containing a high white sapphire is currently sold as a proportion of lead oxide, as this has high natural substitute for diamond. Both fire and brilliance. Diamanté, paste (from natural and synthetic colourless white pâte de verre), Strass and rhinestone are sapphires do not have enough dispersion other names for glass imitations. to be truly convincing as a diamond simulant but are very decent wearing stones for everyday use.

25 CIBJO Retailers’ Reference Guide May 2010 Diamonds Diamond simulants

Strontium Titanate Cubic Zirconia Moissanite This diamond imitation is an artificial Cubic Zirconia (CZ) was introduced in Moissanite was named after Dr Henri product that has no natural counterpart, the mid-1970s and is still one of the Moissan, who discovered this very rare it has almost has the same refractive most effective imitators of diamond. mineral in 1893. The Mohs hardness index as diamond but over four times the It virtually halted production of the of moissanite is above 9, making it the fire. To the trained eye, it looks far too other colourless imitators. It has a hardest mineral after diamond. Moissanite ‘colourful’ to be a diamond. hardness on the Mohs scale of 7.5- used in jewellery is a manufactured gem 8.5 which allows it to have a high- and is well recognised as a diamond YAG (Yttrium-Aluminium Garnet) quality polish and sharp facets. It is simulant. Although it is more expensive and GGG (Gadolinium Gallium manufactured in very large quantities than Cubic Zirconia, its optical properties Garnet) today. It has a high refractive index (refractive index and dispersion) are compared to other imitations and it actually higher than those of diamond, These artificial products, which have is inexpensive to manufacture, making making it an extremely brilliant and no natural counterpart and hail from it the most popular diamond simulant colourful stone. Its hardness is the the 1960s and 1970s. They were very on the market. It has slightly too much highest of all the simulants and so is very popular in their day as they closely dispersion to the trained eye to be a durable when worn in jewellery. Synthetic resembled the appearance of diamond. diamond, but when cut properly it is moissanite has a number of properties In 1972, at the peak of YAG production, convincing, particularly in smaller sizes. that make it easily distinguishable from 40 million carats were produced. When examined with a 10x loupe, diamond. For example slightly yellow body Production of both has now virtually however, it cannot match the surface colour and double refraction. ceased as it has been superseded by flatness, lustre and sharp facet edges the better imitation CZ. of a diamond.

26 CIBJO Retailers’ Reference Guide May 2010 Diamonds Treatments

Some diamonds are created in nature Laser drilling with features that make them less In order to make an inclusion in a desirable or valuable. This has led to the diamond far less visible to the unaided development of a variety of treatments eye it is possible to use a laser to burn to improve the face-up appearance of a channel between the piqué inclusion certain stones, by altering or disguising and the surface of the stone. Any part their clarity or colour. of the piqué not vaporised by the laser is then “bleached” with acid. A laser Clarity treatments drilled diamond was once very easy to Clarity treatments were developed in recognise as very small “tunnels” were the 1970s and consist of laser drilling, reaching the surface, but now with the fracture filling, or a combination of advances in lasering the identity of the the two. laser “tunnel” can easily be disguised by irregular feathery looking holes. Laser drilling is a permanent, irreversible technique that is accepted by the trade, as long as it is disclosed.

An example of laser drilling

27 CIBJO Retailers’ Reference Guide May 2010 Diamonds Treatments

Fracture filling Colour treatments Developed in the 1980s and also known There are two basic types of colour as “clarity enhancement”, the process treatment. The first type involves coating of fracture filling is to force a foreign the surface of a diamond to disguise liquid into surface-reaching feathers or or alter its colour. The second involves cavities. The filler material is commonly actually altering the body colour of the a lead-based glass with a high refractive diamond. Colour treatments are the index. Any crack with filler material in it oldest form of treatment, dating back becomes much less visible and therefore to before the 16th century, and have improves the look of the diamond. Laser normally, but not always, been used drill holes are sometimes filled. to make a poor stone more desirable. Fracture filling is not regarded as being permanent, because the filler material may discolour with age or leak from the stone when being heated during jewellery repair. For day-to-day wear it is considered stable and durable. The treatment can be detected under magnification, by looking for a colourful, An example of fracture filling reflective ‘green-pink or purple-yellow’ ‘flash effect’.

28 CIBJO Retailers’ Reference Guide May 2010 Diamonds Treatments

Surface treatment Body treatment: irradiation Body treatment: High Pressure, High Temperature ‘Foiling’ of diamonds was quite common To actually change the colour of a in the 18th and 19th centuries. It involves diamond, new colour-causing defects The most recent and sophisticated sticking highly reflective foils to the can be created artificially. A stone can development in diamond colour pavilion of a diamond and then mounting be bombarded (i.e. irradiated) by either improvement is to treat brownish it in jewellery with a closed back. atomic or subatomic particles; these coloured diamonds to improve their particles damage the diamond’s internal colour. The colour change is to either Similar results to foiling can be obtained structure, which may change the colour. colourless or fancy yellow/green by ‘painting’ the pavilion or the girdle area The colours created usually range from depending on the starting material of the stone. Felt pen, nail varnish and blue to green. (‘diamond type’). The stones are many other substances have been used. treated using the High Pressure, High Longer exposure to irradiation causes To the trained eye, diamonds coloured Temperature process (HPHT), using the colour to become more intense. with artificial coatings often “don’t look presses similar to the ones used to The colour can be further changed by right”, because they have an unnatural- produce synthetics. These treatments heat treatment. By heat treating the looking colour. Foils and coatings have are irreversible and permanent. Their irradiated stone fancy yellow, orange a tendency to tarnish, rub off and/or detection is difficult with simple or pink diamonds, for example, can discolour over time, and are detectable visual inspection and must be tested be created. Not all diamonds respond with the 10x loupe. If in good condition, by advanced laboratory equipment similarly to this treatment process. antique foiled diamond jewellery can to reveal the HPHT treatment. HPHT It is accepted in the trade only if it is sometimes be a valuable collector’s item. treatments are accepted in the trade but properly disclosed. only if they are properly disclosed. HPHT treatment of diamonds of different types will produce fancy colours.

29 CIBJO Retailers’ Reference Guide May 2010 Gemstones Retailers’ Reference Guide Gemstones Contents: Gemstones

3 Alexandrite and other chrysoberyls 38 Organic gems Coloured gemstone section written by the Gemmological Institute of America, Carlsbad, California. All rights reserved. 6 Amethyst 42 Peridot Images for this section are courtesy of the Gemological Institute of America. Faceted gems courtesy of the Dr. Eduard J. Gubelin 8 Aquamarine 44 Unusual quartzes and chalcedony Gem Collection, now part of the GIA Gem Collection 10 Other beryls 50 Ruby

13 Citrine 53 Sapphire

15 Emerald 56 Spinel

18 Feldspar group 58 Tanzanite

22 Garnet group 60 Topaz

26 Jade 63 Tourmaline

29 Kunzite 66 Turquoise

31 Lapis Lazuli 69 Zircon

33 Opal

All rights reserved. No part of this Guide may be reproduced, republished, amended, translated or changed, including all images included in the Guide, without the express written permission of CIBJO or its authorised agents. Permission to republish, reproduce and/or translate of this Guide is limited to CIBJO member organisations only, and is subject to written agreements between CIBJO and/or its agents and the CIBJO membership organisation.

2 CIBJO Retailers’ Reference Guide May 2010 Gemstones Alexandrite and other chrysoberyls

Appreciation for alexandrite Additionally, the colour changes of Yellow to greenish chrysoberyls are and other chrysoberyls alexandrite – primarily red to green – the only non-phenomenal variety of heralded the official colours of Imperial chrysoberyl – but are the standard Of all of the mineral species, chrysoberyl Russia. bearers for the name of the species. is the most phenomenal – in the sense Chrysos is a Greek work meaning that two of its three varieties possess Among the most cherished gems “golden,” and berilos (also Greek), form unique optical characteristics we’ve come that exhibit chatoyancy (an optical the root for the chrysoberyl name. It to know as phenomena. Alexandrites are phenomenon in certain gems that causes is worth noting that chrysoberyl is not the best-known variety of chrysoberyl, the viewer to see a “floating” line through a form of beryl, which is an entirely exhibiting chameleon-like colour-change the gem) is the cat’s eye chrysoberyl, different species. characteristics. On rare occasions, these which appears to move as the gem or the colour-change gems exhibit a second light source is moved. This phenomenon Alexandrite and other chrysoberyls phenomenon, called cat’s eye effect. is caused by inclusions; minute fibres of on the calendar the mineral sillimanite that are oriented The colour change effect in alexandrites parallel to one another throughout the Alexandrite is an alternate gemstone for is caused by the selective absorption chrysoberyl. In gems that are properly the month of June. Alexandrite is also a and transmission of light, which in turn oriented and cut en cabochon, this silvery, 55th anniversary gemstone. is caused by the colour temperature of floating line appears when a strong or the light in which the gem is viewed. pinpointed light is directed in a direction Alexandrites exhibit warm reddish hues in perpendicular to the gem. Cat’s eyes incandescent light and bluish-green hues are best viewed in direct light such as in daylight. Alexandrites were discovered sunlight. An indistinct cat’s eye effect, in Russia’s Ural Mountains in 1830, in observed as a broader sheen along the deposits along the Takovaya River. The gem’s surface, is caused by a multitude colour change gem was named after Czar of randomly oriented included needles – Alexander II, who is said to have come of this effect is sometimes referred to age the day the gem was discovered. as cymophane.

3 CIBJO Retailers’ Reference Guide May 2010 Gemstones Alexandrite and other chrysoberyls

What chrysoberyl is change sapphires, which often exhibit Refractive Index: 1.746 to 1.755 Chrysoberyl treatments overlapping colours and colour change This species of gem is an alluminate Birefringence: 0.008 to 0.010 While chrysoberyls in general are never phenomena. Cat’s eye chrysoberyl tends of beryllium, with the chemical treated to enhance colour or diminish to be straightforward to identify based Specific Gravity: 3.73 (+/- 0.02) formula: BeAl O , which forms in the the appearance of inclusions, one 2 4 on its optical characteristics, however orthorhombic crystal system. Three main Cause(s) of colour: Predominantly iron well-known case of treated brown cat’s some very convincing look-alikes do exist: varieties comprise the species: golden and chromium in chrysoberyls; Chromium eye chrysoberyls exists. In the 1990s Cat’s eye opal, scapolite, kornerupine, chrysoberyl, alexandrite and cat’s eye in alexandrites and iron (and sometimes some parcels of dark brown cat’s eye tourmaline and quartz – may look similar. chrysoberyl. Non-phenomenal chrysoberyl chromium in rare, cat’s eye alexandrites). chrysoberyls began appearing on the Here again, in the case of alexandrite and is transparent to semi-transparent, market. It was found that the material cat’s eye, a trained gemologist may easily Hardness: 8.5 on the Mohs Hardness comprising a range of colours. The had been irradiated at a nuclear facility separate them from other visually similar Scale. alexandrite variety contains gems that to deepen their brown colours. The gemstones. vary from transparent to semi transparent, Internal identifying characteristics: material was also found to be highly and whose colour appears different Colours: multi-phase inclusions, mica platelets, radioactive and, because of that and the depending on the light it is viewed in. calcite, and pyrite inclusions in chrysoberyls accompanying negative publicity, these • Chrysoberyl (non-phenomenal): Light Cat’s eye chrysoberyl is opaque to semi- and alexandrites. Silky fibres of sillimanite cat’s eyes were soon removed from the to medium yellow to yellowish green, transparent, containing minute parallel inclusions are found in cat’s eyes. market. Nevertheless it was cautioned greyish green, brown to yellow-brown inclusions that cause chatoyancy. then that any deep brown cat’s eye to light blue. chrysoberyls whose provenance could not Among natural gems, non-phenomenal • Alexandrite, daylight: Yellowish, be ascertained – be sent to a qualified lab chrysoberyl may be confused with brownish, greyish or bluish green. for further testing and assurance. yellow or greenish sapphires, grossularite garnets and some spinels, due to their • Alexandrite incandescent light: Orangy colour overlap. or brownish red to purplish red. For more information about CIBJO standards and rules regarding treatments, artificial and Trained gemologists may easily identify • Cat’s eye: Yellow to yellowish green; imitation products, or synthetic stones please and separate these gems based on their greyish green; brown to brownish download a free pdf copy of the CIBJO optical and physical characteristics. yellow. Coloured Gemstone Bluebook: www.cibjo.org Alexandrites may be confused with colour change garnets and colour

4 CIBJO Retailers’ Reference Guide May 2010 Gemstones Alexandrite and other chrysoberyls

Collector chrysoberyls Finally, collectors have become much Care of chrysoberyls more discriminating about the quality Alexandrites and cat’s eye chrysoberyls With a hardness of 8.5 and excellent of cut – symmetry, orientation, crisp are quite rare to begin with and as such toughness, chrysoberyls of all types are facets and facet junctions and appealing highly collectible due to their exotic, extremely resilient for use in jewellery. outlines – since such aspects tend phenomenal qualities. A premium is It is never a good idea to wear gems to show phenomena at its very best placed on gems that contain strong colour during any type of arduous work or and because the overall effect is more change qualities, since with alexandrites exercise. However, chrysoberyls may pleasing to the eye. a predominantly “muddy” mix of greens, be worn daily under normal conditions. browns and reds tends to be the norm, Most chrysoberyl jewellery may be Chrysoberyl localities resulting in a vague colour change. cleaned in an ultrasonic cleaner unless Cat’s eye chrysoberyl may appear in Chrysoberyl, while rare as an occurrence, there are preconditions (such as a a variety of colours, including colour With cat’s eyes, a strong, sharp and is found on several continents – Africa, fractured gem) or if the jewellery metal is change. Cabochons such as this one unwavering silvery line that is visible South America and Asia. Sources for worn thin. Otherwise, a damp cloth and are, in part, judged by how straight from girdle-to-girdle is highly desirable, chrysoberyls, alexandrites and cat’s eyes warm soapy water are generally enough and unwavering the “eye” is. accompanied by rich green, yellow or include Russia, Sri Lanka, Brazil, Kenya, to clean chrysoberyl gems and jewellery. brown colours. Cat’s eye alexandrites are Tanzania, Madagascar, India and Burma. especially collectible since they exhibit two forms of phenomena. An additional and easy confirmation of quality for cat’s eyes is to shine a direct light Alexandrite is the most prominent towards the gem at an oblique angle. variety of chrysoberyl. This is how one In fine, semi-translucent gems a “milk such alexandrite appears in daylight. and honey” effect can be observed. This shows strong brownish to honey colours on one side of the gem, and a milky translucence on the other. In all collector Here is how the same alexandrite The non-phenomenal varieties of varieties, size matters since alexandrite appears in incandescent lighting. chrysoberyl include golden and green as well as cat’s eyes tend to be found to bluish green colours. mostly in under a carat, small sizes.

5 CIBJO Retailers’ Reference Guide May 2010 Gemstones Amethyst

Appreciation for amethyst Amethyst on the calendar Hardness: 7 on the Mohs Hardness Scale. Enthusiasts who appreciate quartz’s Amethyst is the Birthstone for February. Internal identifying characteristics: diverse family of gems often single out It is also considered to be a 6th Amethysts often contain areas of colour amethyst as the most significant variety anniversary gem. next to areas that have no colour – called of the quartz mineral. Amethyst has been colour zoning. Amethyst, which has a used in personal adornment for centuries, What an amethyst is hydrothermal geologic formation, often often sought out by royalty or important has liquid inclusions containing solids Amethyst is a variety of quartz that grows members of the clergy. and gases, so-called two and threephase in a hexagonal crystal system and has the inclusions. Inclusions of other minerals In Medieval Europe particularly, the colour following chemical composition: SiO . 2 such as rutile and hematite sometimes purple was worn in rare dyed textiles Colour(s): Transparent to translucent can be found in amethyst as well. that could only be afforded by the very lilac to purple through bluish purple, wealthy. Amethyst’s bold purple colour, with a reddish purple colour-shift that is Amethyst’s treatments and rare reddish flashes, coupled with the sometimes visible in incandescent light. In fact that only a few mines for it existed Amethyst is sometimes subject to ametrine, a unique form of quartz mined in ancient times, further contributed to heat treatment, which in a controlled from a single locality in Bolivia, the colours its selection as a “royal gem.” Important environment may cause overly dark are both yellow and purple in areas of amethysts feature prominently in British amethysts to be lightened. Occasionally zoning. Such gems are sometimes cut in a regalia. The name amethyst has a peculiar heating amethyst from some sources may way that mixes the colours, and at other derivation. It comes from the Greek word turn them yellow. Heating may remove times to show the division of colours. améthystos, which translates to “not a smoky component in some amethysts. drunk.” An ancient belief that amethyst Refractive Index: 1.544 to 1.553 protected its wearer from inebriation Birefringence: 0.009 For more information about CIBJO standards (even following copious consumption and rules regarding treatments, artificial and of alcohol) consequently made the gem Specific Gravity:2.66 (+0.03, -0.02) imitation products, or synthetic stones please highly desirable by those so inclined. Cause(s) of colour: are colour centres download a free pdf copy of the CIBJO in quartz, natural irradiation in the mine, Coloured Gemstone Bluebook: www.cibjo.org combined with traces of iron.

6 CIBJO Retailers’ Reference Guide May 2010 Gemstones Amethyst

Collector amethysts Some important localities in the United Amethyst is the most significant States, particularly in Arizona, are also variety of the quartz gemstones. Collectors of amethyst look for depth of contributing supplies of amethyst to the purple colour with red flashes if the world markets. gem is cut conventionally. Many famous lapidaries (cutters) work with amethysts The cutting and care of amethysts to make unusual carvings or cuts, which are also highly prized. Because the Amethyst – once considered rare – today bi-coloured ametrine comes from only has thankfully become one of the world’s one mine in the world, it is sometimes most plentiful, and thus democratic of collected if the depth of colour and the gems. It can be found in many sizes. division of colour is strong, or if it has Amethyst is offered in many different been skillfully or cleverly carved. kinds of cuts and carvings. Amethyst Ametrine, a combination of is also fairly resilient and can be worn amethyst and citrine colours, is Amethyst localities extensively. Care should be taken not only found commercially in the to knock the gem during use, as small Russia is considered the “classic” source country of Bolivia. fissures or cracks may develop, especially for amethysts because that is where along facet junctions. It can be cleaned it came from before the discovery of with warm, sudsy water or a dampened amethysts in the New World. “Uralian” cloth. Some amethysts may lighten in or “Siberian” amethysts, at their best, tone over time upon prolonged exposure exhibit deep reddish purple, to purple red to bright light. colours. The discoveries of amethysts in Amethyst inclusions are often Brazil, Uruguay, Bolivia and Zambia have liquid in nature and may contain changed the dynamics of the market 2 or 3 phase inclusions. because much larger volumes of material became available in the 20th Century.

7 CIBJO Retailers’ Reference Guide May 2010 Gemstones Aquamarine

Appreciation for aquamarine milky appearance. In other rare cases, the Hardness: 7.5 to 8.0 on the Mohs inclusions are miniscule, hollow growth Hardness Scale. Aquamarines remind us of the sea; their tubes that form parallel to one another, watery greenish blue colours have elicited Internal identifying characteristics: causing chatoyancy (cat’s eye effect) in such comparisons for centuries. In 1609, Inclusions in fine aquamarines are the gem. German gem cutter Anselm Boetius de sometimes hard to find. However liquid Boodt first drew this association and his inclusions and “fingerprint” inclusions Aquamarine on the calendar description became universal. The Latin as well as 2 and 3-phase inclusions root names, aqua and marina, literally Aquamarine is the birthstone for March. It (containing a liquid, a solid and a gas) translate to “water of the sea.” Aquamarine is also considered to be a 19th anniversary are sometimes found. In cat’s eye is a gem of subtlety with its light and gemstone. aquamarines, parallel hollow growth clear pastel hue; it is often worn for tubes are the cause of chatoyancy. evening events when the gems can gleam What an aquamarine is enticingly, even in low lighting conditions. Aquamarine’s treatments Aquamarine is an important member Despite the understanding that subtlety of the beryl family of gems, and forms More often than not, aquamarines are is part of an aquamarine’s character, in the hexagonal crystal system. It has heat-treated, causing them to lose their depth of colour remains an important the following composition: Be Al Si O . secondary greenish colour component. characteristic as well. 3 2 6 18 Most aquamarine in today’s market is Colour(s): Generally transparent and Aquamarines differ greatly from emeralds, considered to be heat-treated, though it greenish blue, to blue green and generally despite being members of the same family. is generally impossible to determine that light in tone. Some highly included Unlike emeralds, for instance, aquamarines fact gemologically. aquamarines may have a milky, translucent frequently form as large crystals – quality about them. sometimes weighing hundreds of carats. For more information about CIBJO standards Additionally, they frequently possess a Refractive Index: 1.577 to 1.583 (+/- 0.017) and rules regarding treatments, artificial and vitreous clarity not found in emeralds. Birefringence: 0.005 to 0.009 imitation products, or synthetic stones please For this reason, aquamarines may be download a free pdf copy of the CIBJO fashioned as exceptional clean gems and Specific Gravity:2.72 Coloured Gemstone Bluebook: www.cibjo.org carvings. That said, some aquamarines are Cause(s) of colour: iron sufficiently included to impart a slightly

8 CIBJO Retailers’ Reference Guide May 2010 Gemstones Aquamarine

Collector aquamarines Aquamarine localities The cutting and care of aquamarines Aquamarines that have saturated, light Aquamarines form in pegmatite localities blue colours are especially desirable, on almost all continents on earth. Brazil is Aquamarine’s rating of 7.5 to 8.0 on the though a few beryl collectors prefer a slight perhaps one of the best-known localities for Mohs Hardness Scale, combined with its greenish tinge. Such gems are considered aquamarine – as well as various other beryls. relatively inclusion-free crystallography to follow a more “classic” description of gives it good toughness as a gemstone The gem-rich state of Minas Gerais is aquamarine. Unusually cut gems are also if it is worn under normal use. Larger Some aquamarines may be Brazil’s strongest producer, though fabulous popular, especially in gems that have been aquamarines should be worn with care, lightly heated to remove a finds have occurred in Rio de Janeiro, fashioned by an important lapidary artist. especially in settings such as rings that can slight greenish component. Espirito Santo and Bahía as well. Aquamarines and other beryls often lend be easily knocked. It is best when prongs themselves to sculptures because of their Other strong producers include Pakistan’s are placed in corners of square-shaped size. Locality plays a role in collecting as well. Skardu district and Ukrainian beryls from gems, because they can protect the gems Aquamarines from desirable localities, such Russia. Other Asian localities include from chipping at sharp angles and facet as Santa Maria aquamarines from Itabira, in Tajikistan and China – China particularly junctions. An aquamarine may be placed Brazil, are collectible in accordance to their is emerging as an important producer. in an ultrasonic cleaner if it is judged that legendary depth-of-colour. Ukrainian green Aquamarine is also mined at several it does not have inclusions that might beryls and aquamarines also became sought localities in the United States, but perhaps expand or endanger the integrity of the after as mineral specimens thanks to their the most significant is Mt. Antero in gem. Sudsy water followed by wiping with startling sizes, peculiar growth etching and Colorado. African aquamarines have a damp cloth is a good and safe way to deep colours. been found at deposits in Kenya, Malawi, clean an aquamarine. Tanzania, Namibia and Madagascar.

Carving aquamarines to this degree of fineness requires Aquamarines are found enormous skill, particularly in various tonalities. since aquamarine is a very hard gemstone.

9 CIBJO Retailers’ Reference Guide May 2010 Gemstones Other beryls

Appreciation for beryls was shown at the World’s Fair in Paris, Red beryl – (also named bixbite, after France (at the time the Eiffel Tower its discoverer, Maynard Bixby) is not Aficionados often praise the many pastel was first built). Despite this prominent pastel coloured but a strong, red colour, colours available in the beryl species link, morganite is in shorter supply than and generally very small – under one – notably the subtle blues observed in aquamarine, and consequently is less well carat. Red beryls were discovered as rare, aquamarine. But a handful of other colour known. However, morganites occasionally non-commercial crystals in the early varieties grace it as well. Pink to peach form as large crystals, as such are suitable 1900s, but it was only in the 1950’s that colours, yellow, colourless, light green, for oversized gems or carvings. This is also larger quantities, sufficient enough to deep blue and –very rare – red colours are true for heliodor, the bright yellow beryl build a business were found. Red beryl also part of this family. It is worth pausing whose name is derived from the Greek remains unique to North America, and for a moment to remember that emerald word helios, meaning sun. Occasionally, production is sporadic at best. It is a gem is also a beryl variety. if the yellow colour of the gem is deep for collectors. Emerald’s importance as the deep green enough, or contains some orange colour, Maxixe beryls, primarily found at a locality gem par excellence is well established the gem is also referred to as golden in the State of Minas Gerais, Brazil, are throughout history. Aquamarine is a beryl. Goshenite, named after Goshen, a medium to dark blue when mined and significant beryl too, and for that reason Massachusetts where it was found extracted from the earth, but the colours individual chapters for these two gems describes a beryl crystal or cut gemstone fade quickly upon exposure to light (or have been written. (See Emerald p. 15 that is essentially colourless. All of the heat). Much like red beryl has its followers, or Aquamarine p. 8). Pink beryl was first varieties of beryl owe their colour to trace so too does maxixe. Collectors take great discovered in Pala, California (together impurities of another element; goshenite pride in their collections of the deep blue with other gems including kunzite and is the purest form of the species, and thus beryl. But they only take them out of their tourmaline). The new gem was soon colourless. Green beryl is a unique gem: dark containers every once in a while to named morganite in honor of U.S. financial it is not sufficiently toned or saturated remind themselves of the beautiful, if mogul, John Pierpont Morgan, who was enough to be called an emerald, which ephemeral, deep blue colour. an avid collector, particularly of North is why this gem classified separately. It is American gems. Morgan was reputed to no surprise that borderline emerald/green have had the largest collection of gems beryl gems sometimes a challenge to and minerals in the United States during determine. the late 1800s. In 1889, his collection

10 CIBJO Retailers’ Reference Guide May 2010 Gemstones Other beryls

Beryls on the calendar Refractive Index: 1.577 to 1.583 (+/-0.017) Beryl treatments: For more information about CIBJO standards Only emerald and aquamarine Birefringence: 0.005 to 0.009 a. Heating – Morganite responds to and rules regarding treatments, artificial and are considered as birthstones and some heat treatment, by removing a imitation products, or synthetic stones please Specific Gravity: 2.72 (+0.18, -0.05) anniversaries. Please look at the yellow colour component and thereby download a free pdf copy of the CIBJO specific chapters for these gems Cause(s) of colour: pink and red are cause rendering a deeper pink colour. The Coloured Gemstone Bluebook: www.cibjo.org for additional details. by manganese; yellow is caused by iron; colour is considered stable. green is caused by chromium, vanadium b. Irradiation – Sometimes goshenites What beryls are: and iron. Maxixe’s colour is caused by Collector beryls (colourless beryls) may be irradiated to unstable colour centres. Note: Studies Beryls form in the hexagonal crystal produce yellow colours. This colour is Large beryls that exhibit a high degree indicate that maxixe’s colour can be system. They have the following chemical considered stable. Maxixe colours may of saturation are always in demand. temporarily restored through irradiation composition: Be Al Si O . be restored through irradiation, through Collectors often like to have all the 3 2 6 18 treatment, though the colour is not stable. the colour also fades to light and heat. varieties in a species. Other collectors Regarding colour ranges, green beryl Hardness: 7.5 to 8 on the Mohs Hardness Note: For all intents and purposes, prefer to specialize in rare gems, such (other than emerald) may be strongly Scale. maxixe beryl is almost always irradiated as red beryls. Borderline gems (Is it an bluish green to green to yellowish green –either naturally as it comes out of emerald? Or a green beryl?) also have (generally in lighter tones and saturations). Internal identifying characteristics: The the ground, or in a laboratory. Some admirers. Cat’s eye beryls are rare and Morganite may be reddish orange through pastel coloured gems tend to have fewer colourless and light pink beryl from therefore collected. slightly purplish red (generally in lighter inclusions than saturated varieties. Liquid Minas Gerais is irradiated to produce tones and saturations). Yellow beryl may fingerprints, two phase inclusions and maxixe beryl. Beryl localities be greenish yellow through orangy yellow hollow growth tubes are possible in all (generally in lighter tones and saturations). varieties, sometimes causing chatoyancy c. Oil impregnation – While oils and Brazil produces much of the world’s Red beryl is far more saturated than (cats eye effect). polymer resins are rarely used with pastel beryls – and maxixe. Afghanistan, morganite and maxixe should be more pastel colour beryls, colourless oil and Russia, Madagascar, Zimbabwe, United saturated than aquamarine. resins are sometimes used to hide States also produce various kinds fissures in red beryl. of beryls. Only the United States commercially produces red beryl.

11 CIBJO Retailers’ Reference Guide May 2010 Gemstones Other beryls

The cutting and care of beryls Pastel coloured beryls have plenty of devotees of their own, though emerald Beryls may be cut several different ways, (the deep green gem bottom, centre) is though emerald cut and oval cut gems probably the best known of the beryl tend to predominate. Beryls are generally family. Here you can see goshenite (top quite hardy unless they are strongly row left), golden beryl, morganite, and included. Red beryls tend to be more like green beryl. In the second row (starting emerald in this respect and may be fragile left): morganite, maxixe beryl, green if the gem has many surface reaching beryl, heliodor, and green beryl. Third fissures. For safety’s sake, ultrasonic row: red beryl (or bixbite) and emerald. cleaners and steamers should be avoided. A dampened, non-abrasive cloth is best used to clean beryl jewellery.

While some may find it difficult to determine the separation between green beryl and emerald, the emerald (centre) is always more vivid in colour.

12 CIBJO Retailers’ Reference Guide May 2010 Gemstones Citrine

Appreciation for citrine amethysts, which, upon being heated, turn Hardness: 7 on the Mohs Hardness Scale. a brownish yellow or yellow colour. Citrines The description for citrine is contained Internal identifying characteristics: are greatly esteemed for their warm, earthy in its name. Citrine, from the French Citrines are often devoid of eye-visible colours and for their vivacious sparkle, word citron literally means “lemon,” in inclusions though some material may especially among lighter toned gems. deference to a multitude of rich yellow show colour zoning. In some cases, fluid hues. There are several sources for the inclusions and negative crystals may be Citrine on the calendar gem, and consequently the gem is seen. Inclusions of other minerals such available to many people around the Citrine is an alternate birthstone for as goethite or rutile can also be found world who love gemstones. November. It is also considered a 13th in citrine. anniversary gem. Citrines actually cover a much wider range Citrine’s treatments of yellows than do most lemons, including What a citrine is: rich, orangy yellow colours. In deep orange, Many citrines start out as amethysts it is reminiscent of a gem from a different Citrine is a variety of quartz that grows in but are heat treated to turn yellow to species called topaz. There is no relation a hexagonal crystal system and has the yellowish brown. Heat treatment of

between topaz and citrine whatsoever, following chemical composition: SiO2. amethyst requires considerable experience, despite misnomers such as “topaz quartz” and not all amethysts may respond in a Colour(s): Citrine is transparent to or “Madeira topaz” which are sometimes manner that is expected. However, altered translucent pale yellow to deep orange incorrectly used to describe a particular colour is considered stable. and/or brownish orange colours. hue of citrine quartz. In fact, citrine has significant attributes of its own to stand Refractive Index: 1.544 to 1.553 For more information about CIBJO standards upon: aside from its rich and optimistic Birefringence: 0.009 and rules regarding treatments, artificial and colours, it is found in an impressive range imitation products, or synthetic stones please of sizes and quantities, making it a favourite Specific Gravity: 2.66 (+0.03, -0.02) download a free pdf copy of the CIBJO for well known gem carvers to work with. Cause(s) of colour: Traces of iron are the Coloured Gemstone Bluebook: www.cibjo.org While citrine quartzes are found in principal cause of yellow. Heat treatment of nature and on a variety of continents, the certain kinds of amethyst under controlled majority of these gems began their lives as conditions also causes the yellow colour.

13 CIBJO Retailers’ Reference Guide May 2010 Gemstones Citrine

Collector citrines The cutting and care of citrines Citrine quartz is generally perceived as an optimistic yellow colour. The gem may Collectors of citrine look for a pure yellow Citrine is thankfully one of the world’s most exhibit stronger and weaker zones of or orange colour to begin with. Many plentiful gems. It can be found in many colours throughout the gem, such as with famous lapidaries (cutters) work with sizes. Citrine is often cut as large gems or in this gemstone. citrines to make unusual carvings or cuts, carvings. Citrine is also fairly resilient and which are also highly prized. Because may be worn extensively, though wearing ametrine – a form of quartz that combines citrine during any type of manual labor the colours of amethyst and citrine – or strenuous activity should be avoided. comes from only one mine in the world, Care should be taken not to knock the gem it is collectible if the depth of colour and during use, as small fissures or cracks may the division of colour is strong, or if it has develop, especially along facet junctions. been cleverly carved and fashioned. It is best cleaned with warm, sudsy water or a damp cleaning cloth. Citrine localities Brazil is considered one of the main sources of citrine; particularly from the Different shades of yellow quartz are gem rich states of Minas Gerais and Rio all known as citrine. Some citrines are a Grande do Sul. Bolivia’s Anahi mine has darker tone as well and may be seen as also become a leading producer of citrine. orange to brown. It is also found in African countries such as Tanzania, Namibia and Zambia.

Viewed at 30x through a microscope, sprays of the mineral goethite may be found in some citrines and other quartzes.

14 CIBJO Retailers’ Reference Guide May 2010 Gemstones Emerald

Appreciation for emeralds Pliny was one of the first to classify Emerald on the calendar gemstones, including emeralds. But It is an emerald’s appearance and colour Emerald is the birthstone for the month appreciation for emeralds was evident that make this gemstone instantly and of May. It is also considered a 20th long before him. It is thought that universally recognized. The rich, green anniversary gem. emeralds were first used as gemstones hue has also been the primary reason for circa 3500 B.C., during the first dynastic the gemstone’s tremendous popularity What an emerald is reigns of Egypt’s kings and so, for throughout human history. In many thousands of years, Egypt was the world’s Emeralds are a variety of the beryl species instances, the word “emerald” is used to main emerald source. Actress Elizabeth of minerals and are composed of the define saturated variations of green, such Taylor, who played Queen Cleopatra on following elements: Be Al Si O . as the lush vegetation of the “emerald 3 2 6 18 film, was equally enamored of emeralds isle,” or an “emerald green ocean.” Marbod, Beryls include the following other gemstone as the Egyptian she portrayed. Aside from the medieval poet of Rennes, France, loved varieties: aquamarine, morganite, red beryl, wearing magnificent emerald jewellery emerald’s colour, causing him in 1120 A.D. green beryl, heliodor and goshenite. (Note: throughout her life, Taylor used the colour to have observed the following: more about the beryl family in specific and popularity of emeralds to launch chapters on: Aquamarine, and also: Other “Of all green things, which the bounteous a perfume in recent years. Beryls.) Emeralds and other beryls grow as earth supplies, Nothing in greenness with Emeralds have also been celebrated as hexagonal (six-sided) crystals. The following the emerald vies.” birthstones for those lucky enough to be optical, physical and chemical factors help Hundreds of years earlier, the naturalist born in the month of May. It represents distinguish the emeralds: Pliny the Elder (23A.D. to 79A.D.) declared rebirth and eternal spring. Its colour Colour: Vibrant, deep green colour that his sentiments as well: denotes honesty, and integrity; finally, is often described as very strongly bluish emeralds have long been thought to be “We delight in feasting our eyes on the green through green. capable of soothing one’s eyes. pleasant green grasses and leaves, but Refractive Index: 1.577 to 1.583 the enjoyment of beholding an emerald is The Roman Emperor Nero is said to have incomparably greater, for its green is most watched gladiator fights through emerald Birefringence: 0.005 to 0.009 soothing.” slices for that very reason! Specific Gravity: 2.72 (+0.18, -0.05)

15 CIBJO Retailers’ Reference Guide May 2010 Gemstones Emerald

Cause of colour: Chromium generally, are fascinating to examine through a or fashioning) was first described by Pliny Collector emeralds sometimes vanadium and sometimes a microscope, and provide positive proof of and as such has probably been practiced Deeply coloured, large, relatively clear combination of chromium and vanadium. the gemstone’s natural origin. Occasional to varying degrees for centuries. Because and non-treated emeralds are rare and larger fissures (especially those located at introducing substances into emeralds may Hardness: 7.5 to 8 on the Mohs Hardness collectible. There are also two rare kinds of corners where a prong might be placed) substantially change their appearance (and Scale. unusual collector emeralds that are rarely should be avoided. The majority of perceived value) the presence of these seen commercially: Internal identifying characteristics: emeralds are very durable gemstones that kinds of treatments needs to be disclosed multi-phase inclusions, mica platelets, will bring joy to successive generations if from the seller to the buyer along the Cat’s eye – These beryls are green enough calcite, and pyrite inclusions. It is worth handled with appropriate care. Emerald supply chain. Even when such treatments to be classified as emerald, and have reflecting further on an emerald’s unique shares similar inclusion characteristics are fully disclosed, new care considerations multiple, microscopic hollow growth tubes internal characteristics since they are with red beryl, due in part to their colour need to be explained as well. Some oils, that form in a parallel fashion to one so prevalent in emeralds. Inclusions in causing impurities and their mode of paraffin and some resins may seep out of another throughout the gem. Emeralds emeralds are considered customary and formation. Conversely, lighter beryls, the fissures, especially when subjected to such as these are fashioned en cabochon expected. While emeralds with no eye- such as aquamarine and morganite, are heat or pressure. Others may oxidize over and the domed surface of these gems visible inclusions do exist – these gems are very often eye-clean (viewed without time so it becomes important for sellers exhibits a cat’s eye phenomenon in direct extraordinarily rare. Some inclusions magnification) even in sizes larger than to be able to offer services to clean and (non-diffused) lighting. in emerald are referred to as jardin, 5 carats. re-treat an emerald if so required. Trapiche – These Colombian emeralds (meaning garden in both French and celebrate unique six-spoke inclusions, Spanish) and may consist of networks of Emerald treatments For more information about CIBJO standards (similar to spokes on a bicycle wheel) tiny liquid filled inclusions and minute The minute fissures that are found in and rules regarding treatments, artificial and containing either black carbonaceous fissures that permeate the gem, lending it many emeralds lend themselves to a imitation products, or synthetic stones please shale (the host in which these emeralds the appearance of a lush garden – hence form of treatment by humans, aimed at download a free pdf copy of the CIBJO form), or white albite (a form of feldspar) the term. These inclusions also impart diminishing or masking the inclusion’s Coloured Gemstone Bluebook: www.cibjo.org spokes. These gems are cut as slices or as the emerald with a distinctive, somewhat appearance. These fissures often reach cabochons to show the spokes radiating hazy appearance because they diffuse the surface and may be filled with out from the centre. The name comes and spread light through the gemstone. substances including oils, paraffin, resins from wheel-like sugar cane crushers found Emerald’s transparency and surface and polymers. The manipulation of an in Colombia, called trapiches. luster is often described as glassy or emerald’s appearance (other than cutting vitreous. Included crystals, such as pyrite,

16 CIBJO Retailers’ Reference Guide May 2010 Gemstones Emerald

Emerald localities Cutting and care of emeralds emerald treatments. Emeralds should not be immersed in detergents for similar South America has stood out as the Emeralds are the only gems that have a reasons, and are best cleaned with a world’s primary source for the green specific cut named after them. The term water-dampened, soft cloth. Common gemstone since the discovery of the “emerald cut” is a square or rectangular sense indicates it is not a good idea to New World. The Incas traded emeralds outline step-cut, containing tapered wear an emerald ring during gardening throughout their Andean empire until the corners. Many emeralds are cut this way or other intense physical activity. arrival of Spanish Conquistadors. But the because it orients the gem to show its Spanish discovery of emeralds in Colombia strongest colour. These cuts contain large This fine emerald comes from the in the 1500s changed the balance of table facets through which an admirer Colombian emerald region of Chivor. power in South America. Egypt’s emerald can best view the emerald’s rich colour sources were quickly forgotten as and its fascinating inclusion panorama. Even fine emeralds, such as this deep European nobility demanded Colombia’s Emeralds are increasingly cut in other green gem, generally contain inclusions superb emeralds. This South American shapes, including round, oval, free form, that may be visible to the eye. These source quickly became the world’s most pear and marquise. With the latter two characteristics are signatures of the significant producer of fine emeralds, and cuts in emerald it is important to closely emerald’s natural origin, and are often remains so today. However, many other examine pointed corners for durability referred to as “jardin,” – meaning garden sources are gaining importance, including issues. It might be recommended for – in both French and Spanish. mines in Brazil, Zambia, Madagascar, such gems to be mounted in earrings, Pakistan, Afghanistan, Russia and China. pins or pendants (rather than rings) in A few emeralds have been found on the order to minimize potential damage to Three-phase inclusions in emeralds from North American continent as well; Hidden, sharp points. It is also recommended Muzo, Colombia, can be seen through North Carolina, is the U.S.’ historic emerald that emerald jewellery owners have their a microscope at magnifications of 10x source, and some emerald material jewelers examine prongs periodically and higher. They are so-called because has also been discovered in the Yukon to ensure the emerald’s security in they contain a fluid, a gas (the rounded Territories, Canada. Neither location is the mount. It is not recommended bubble), and a solid (the square crystal commercially active, though rare collector that emeralds be inserted in ultrasonic of halide). gems surface from time to time. cleaning machines because the heat and vibration may harm or remove

17 CIBJO Retailers’ Reference Guide May 2010 Gemstones Feldspar group

Appreciation for feldspars moonstones exhibit adularescence, which In certain light conditions, a broad, multi- is descried as a “billowy” light effect, or coloured sheen appears to float along the Feldspars, as a gem group, include sheen, observed along the gems’ surface. gem’s surface, particularly visible as the an extremely diverse group of gems In moonstones with a white body colour, gem, or the light source, is moved. This combining several species and varieties. “billowy blue” colour may be seen. In yet iridescent effect is called labradorescence. Many varieties in this family of gems other moonstones, asteriation or cat’s eye In recent years, andesine – rare, albite-rich possess unique optical phenomena. effects (other phenomena) can sometimes plagioclase feldspar has gained recognition. Feldspars are mostly classified as be observed. Moonstones may have It began entering the market in surprising common rock minerals; they are found orangy, brownish or greenish body colour. quantities in 2002. The material has been on every continent. (It is estimated found to come from at least two known that feldspars make up well over half Not to be outdone in moonstone’s localities: Inner Mongolia and Tibet. of the earth’s crust). However, the rare celestial designation, another feldspar feldspars are those beautiful gems that variety is called plagioclase sunstone. This Microcline feldspar has one gem variety are sought after and revered, as they have gem often exhibits warm red to brown called amazonite, which is bluish green been for centuries. In India, for example, and yellow body colours, an allusion to the to green in colour, and may be semi- moonstones (a variety of orthoclase name. Its phenomenal nature, however, translucent to opaque. Interestingly, the feldspar) have long been thought to be is equally captivating. When interacting name has nothing to do with the actual sacred. George Frederick Kunz, a famous with light, similarly oriented, miniscule Amazon rainforest, where it has not gemologist and consultant to Tiffany & inclusions of copper or hematite platelets been found as a source. The beauty and Co in the late 1800s, notes in his book, exhibit glittering, spangled reflections, intrigue of amazonite is revealed under The Curious Lore of Precious Stones, that shimmering through different depths direct lighting, when a fibrous interlacing “As a gift for lovers the moonstone takes within the gem. Some experts refer to this between green and white streaks can high rank, for it is believed to arouse the phenomenon as aventurescence; others clearly be seen along the gem’s surface. tender passion.” refer to this optical effect as schiller. On rare occasions, the gemstone may also have a slight glittery effect under different It is easy to see why: the way moonstones Labradorite, named after the first place it lights, also caused by inclusions. In this interact with light often reveals their most was discovered – the Labrador Peninsula in case the effect is called aventurescence. alluring characteristic. Under direct (and Canada, is yet another form of plagioclase sometimes subdued) lighting conditions, feldspar that has a phenomenal effect.

18 CIBJO Retailers’ Reference Guide May 2010 Gemstones Feldspar group

Gem feldspars occur in non-phenomenal, Orthoclase: (moonstone) colourless to Cause(s) of colour: The causes of colour in Feldspar’s treatments transparent varieties as well, particularly white, green, yellow brown or grey and feldspars have much to do with the makeup Treatments in feldspars are not generally in plagioclase, oligoclase and orthoclase rarely black. of the gem trace elements and inclusions common, though wax impregnations species. In this case, the body colour is they host. In amazonite, the colour appears Plagioclase: (labradorite) grey to black of tiny fissures that reach the surface generally yellow – but greenish yellow and to be caused by lead (rather than copper, as bodycolour, colourless, green, yellow orange of some amazonites has been reported. colourless varieties occur as well. commonly thought), and the yellow reddish to brown or brownish red. (Oligoclase) This gives the gem a more uniform look. to brown colours often by hematite, copper yellow to green as well as transparent. However, such treatment is not permanent Feldspars on the calendar or iron traces. In sunstones from Oregon, and can be affected by heat and pressure. Refractive Index: the colour is predominantly caused by Moonstones are birthstones for June, It has also been reported that some white copper inclusions. together with pearls and alexandrites. Microcline: 1.522 to 1.530 microcline varieties may be irradiated Hardness: all feldspar species and varieties: to achieve deep blue-greenish colours Orthoclase: 1.518 to 1.526 What Feldspars are 6 to 6.5 on the Mohs Hardness Scale. associated with amazonite. In some Plagioclase: 1.559 to 1.568 (labradorite), instances moonstones and transparent The chemical composition for feldspars is Identifying Feldspar’s characteristics: 1.537 to 1.547 (oligoclase) labradorites may be backed with a black KAlSi O . Microcline feldspars (amazonite) The most important thing to remember is 3 8 coating to better exhibit their phenomenal are part of the triclinic crystal system; Birefringence: that the inclusions in feldspars are what characteristics. In un-mounted gems, orthoclase feldspars (moonstones and provide them with their phenomenal Microcline: 0.008 this treatment is easily discernible. Some transparent varieties) are in the monoclinic characteristics. In sunstones from Oregon, andesine was recently revealed to be crystal system; plagioclase and oligoclase Orthoclase: 0.05 to 0.008 colour is largely influenced by the copper treated by diffusion to achieve rich red feldspars (labradorite and sunstones and content of the gems, and the spangled Plagioclase: 0.007 to 0.10 and yellow colours similar to those found transparent varieties) are in the triclinic inclusions are themselves extremely small in sunstone. crystal system. Specific Gravity copper platelets. Sunstones from Africa contain different inclusions composed Colour(s): Microcline: 2.56 mainly of hematite and mica platelets, For more information about CIBJO standards Microcline: (amazonite) light green to Orthoclase: 2.58 which also cause the aventurescent effect. and rules regarding treatments, artificial and greenish blue, white and rarely light In moonstones interesting inclusions with imitation products, or synthetic stones please Plagioclase: 2.70 (labradorite), orange or pink. a “centipede” appearance may sometimes download a free pdf copy of the CIBJO 2.65 (oligoclase) be seen. Such inclusions are considered Coloured Gemstone Bluebook: www.cibjo.org identifying features for the gem.

19 CIBJO Retailers’ Reference Guide May 2010 Gemstones Feldspar group

Collector feldspars oligoclase) are found in the Unites States Plagioclase feldspars, such as these and Canada. The most plentiful source of include labradorite (top) which exhibits Feldspars that exhibit double phenomena sunstone is the United States- primarily in labradorescence; as well as a variety (adularescence or cat’s eye) are collector’s south central Oregon State. As noted, new of colours of transparent and semi gems because of their rarity. Large gems mines for andesine have been reported in translucent sunstones (below). and richness of colour are also factors Tibet and Inner Mongolia. which collectors consider. Though feldspars have perfect cleavage (they can separate The cutting and care of feldspars along planes of atomic growth in the crystal), and can be damaged during the Feldspars, properly cared for, may last fashioning process, they are sometimes for a lifetime, despite being somewhat carved. brittle at times. Cutters, who properly understand the hardness and toughness Feldspar localities of feldspars, often cut them as cabochons, which (unlike faceted gems) are less Microcline: Amazonite is found in the subject to abrasion along facet junctions. Unites States, mainly in the State of Additionally, cabochons are more likely to Colorado, but also in Madagascar, Burma exhibit the phenomenal aspects of these (Myanmar), Germany and Russia. gems. Some lapidary artists choose to Orthoclase: Sri Lanka, India and Burma carve these gems. Clearly, feldspars are Inclusions in feldspars of all kinds are the are the major sources of moonstones. somewhat delicate and care must be taken principal cause of optical phenomena in Canada, Mexico, Madagascar and the in setting them. many of the more celebrated varieties, United States are major sources of Feldspars should never be placed in such as the aventurescence in the copper transparent orthoclase. ultrasonic cleaners. A clean, water- containing sunstone, (left). Inclusions Plagioclase: Finland is a classic source dampened cloth, containing no soaps or also cause cat’s eye moonstone (centre), for labradorite (gems from this source are cleaning agents, is the best way to clean and the sunstone containing glittering sometimes referred to as “spectrolite”) but the gems. hematite platelets (right). Madagascar is also a very strong source of the material. Transparent plagioclases (and

20 CIBJO Retailers’ Reference Guide May 2010 Gemstones Feldspar group

Moonstones are appreciated for the soft, Moonstones, which can be both billowy glow that appears to float over orthoclase or plagioclase feldspars, the surface of the gems under particular can occur in several colours, such as lighting conditions. These moonstones the ones seen here. exhibit a blue adularescence.

A network of white, fibrous inclusions are part of the charm and character of amazonite feldspar.

21 CIBJO Retailers’ Reference Guide May 2010 Gemstones Garnet group

Appreciation for garnets Most people tend to think of garnets Not all garnets are found in the warm hues. as red, and in fact the Latin derivation Demantoid, from the andradite garnet Several colorful gemstone species and of the name reflects that. The phrase family, is bright green, though other forms varieties are members of the garnet group. malum granatum refers to the striking of andradite may be yellowish or brown The diversity of garnets – principally in resemblance some red garnets have to in color. Demantoid derives its name color and appearance, places them among pomegranate seeds – especially when from the word “demant” which is itself a gemology’s most alluring, yet contentious, the garnets are in the rough. Red garnets derivation of the German word for diamond subjects. The allure is because these gems include pyrope (from the Greek pyropos, – diamant, though the two species of gem are found in variations of almost every meaning fiery). Another red garnet is are not related. While Demantoid colors hue. These various kinds of garnets are almandine. Some garnets fall between certainly don’t bring diamonds to mind, linked to one another by their common pyrope and almandine in composition. For their incredible brilliance and scintillation crystal growth structure and basic chemical example, a violetish red variation is known do. Curiously, pyrope garnets are often composition. There the beautiful similarities as rhodolite garnet in the trade. Since found in association with diamonds during wane, and the controversy begins. The ancient times, reddish garnets have also the mining process, and diamond miners optical, physical and chemical properties been described as “carbuncles,” a reference think of garnets as “indicator minerals” in of many garnets overlap, making it difficult to hot, glowing coals. This is seen as yet their search for diamonds. even for gemologists to pinpoint the another attempt to describe the gems’ distinct species and varieties of the garnet Grossular garnets are principally known brilliance and blazing red color. group. Gemologists’ attempts to classify through the brilliant green tsavorites, garnets have led at times to academic But garnets form in deep yellow, (and garnets that are found in East Africa, disagreements that luckily have no bearing no less fiery), orange colors as well. principally Kenya, not far from the Tsavo on consumer’s tastes for the colors and Spessartine garnets, (sometimes called National Park. Africa is the principal source beauty that garnets impart. Certainly, spessartites in the trade) are named after of many garnets that are challenging garnets have always been appreciated, even the region of Spessart, Germany where to classify. The malaya garnet, a pyrope long before the birth of Jesus. Garnets are they were first found, are a deep yellow spessartine mix, is often found in unique mentioned in the Bible as well: the famous and sometimes orange color. A spessartine purplish to brownish colors. breastplate of the Jewish High Priest is said garnet locality in Namibia produces a to have contained a garnet amongst its glowing orangy gem that has come to be twelve featured gems. known as a “mandarin” garnet in the trade.

22 CIBJO Retailers’ Reference Guide May 2010 Gemstones Garnet group

Garnets are also appreciated for their What garnets are: Refractive Index: Specific Gravity: interesting phenomenal varieties. In Garnets are a group of minerals in the Almandine (also called almandite): Almandine: 4.05 the United States, Idaho produces an cubic crystal system, whose chemical 1.790 (+/- 0.030) interesting four-rayed star garnet. In Andradite: 3.84 formula varies as follows: New Mexico (and in Mexico) a form Andradite: 1.888 (+0.007, -0.033) Grossular: 3.61 of andradite garnet displays incredible Almandine: Fe Al (SiO ) 3 2 4 3 Grossular: 1.740 (+0.020, -0.010) iridescent colors in bright lights. A garnet Hydrogrossular: 3.47 Andradite: CA Fe (SiO ) rarely found in Madagascar displays 3 2 4 3 Hydrogrossular: 1.720 (+0.010, 0.050) Malaia: 3.78 remarkable alexandrite-like, color-change Grossular: Ca Al (SiO ) 3 2 4 3 Malaia: 1.760 (+0.020, -0.018) characteristics. A pyrope spessartine mix, Pyrope: 3.78 Hydrogrossular: Ca Al H O this gem changes from a gray or violetish 3 2 12 12 Pyrope: 1.714 to over 1.742, Rhodolite: 3.84 blue in daylight, to a deep, purplish red in Pyrope: Mg3Al2(SiO4)3 1.74 is normal incandescent light. Spessartine: 4.15 Spessartine: Mn3Al2(SiO4)3 Rhodolite: 1.760 (+0.010, -0.020) Cause(s) of colour: In red garnets a Garnets on the calendar Colour(s): Garnets predominate in red, Spessartine: 1.810 (+.004, -0.020) mix or iron, magnesium and manganese orange and yellow color variations but Garnets are the birthstone for January – Birefringence: None. Garnets are causes the colors we see. Iron, and can also be found in variations of green, and while consumers sometimes believe singly refractive. combinations of iron and manganese, blue, violet and black. Minute variations they are limited to choosing only red is the principal causes of color in yellow in chemical composition are the principal garnets, it is clear they can choose many and orange garnets. Chromium is the cause of the color variations in garnet. different colors. Garnets are a gem of principal cause for andradite garnet’s choice for second anniversaries. green color. In tsavorites a mix of chromium and vanadium results in the greens.

23 CIBJO Retailers’ Reference Guide May 2010 Gemstones Garnet group

Hardness: Most garnets: 7.0 to 7.5 on Garnet treatments Collector garnets the Mohs Hardness Scale. Andradite and Garnets are one of the few gems that are Garnets have been used since antiquity, grossular garnets may be softer; often rarely treated to enhance color or clarity. In especially as engraved gemstones, and between 6.0 and 7.0 on the Mohs scale. rare instances green andradite garnets may such gems are highly collectible. In Internal identifying characteristics: be heated to enhance colors. This treatment reddish garnets the size and pureness of In almandine, pyrope and rhodolite: involves low heat so as not to damage the color is highly desirable. Green garnets tiny, oriented rutile needles may be collectible “horsetail” inclusions. are almost always small – gems over East African countries such as Tanzania are seen in clusters (or nests). These 3 carats are considered rare and are principal sources for garnets such as the sometimes are prevalent enough though therefore collectible. Demantoids often rhodolite (a pyrope) and malaya (a mix of For more information about CIBJO standards the gem to cause a star effect (asterism). have signature “horsetail” inclusions pyrope, spessartine and almandine garnets). and rules regarding treatments, artificial and Other included crystals are found in composed of byssolite and/or chrysotile. imitation products, or synthetic stones please these garnets. Clever cutters will attempt to leave such download a free pdf copy of the CIBJO inclusions in the center of the gem to Coloured Gemstone Bluebook: www.cibjo.org exhibit a classic, collectible gem.

Garnets are part of a diverse and complex gem group. Shown here are several types of garnets including (top row) spessartine, rhodolite pyrope and grossular. (Bottom row) includes spessartine, rhodolite and andradite (demantoid) garnets.

24 CIBJO Retailers’ Reference Guide May 2010 Gemstones Garnet group

Garnet localities The cutting and care of garnets Green grossular garnets’ vivid green colour competes with many other Almandine: India, Sri Lanka, Madagascar, Garnets are generally somewhat species of green gemstones. Those who Brazil, Greenland, Kenya, Pakistan, Tanzania, susceptible to heat (and to some acids) appreciate garnets often point to a and the United States. so it is recommended that garnets garnet’s brightness and durability. be cleaned with soft, non-abrasive, Andradite: Italy, Korea, Russia, (the classic dampened cloths. Garnets may abrade source for Demantoids) Namibia, Mexico along facet junctions if scraped. and United States, especially for the phenomenal iridescent variety. Grossular: Sri Lanka, Kenya, Tanzania, Brazil, Canada, India and United States. Hydrogrossular: South Africa, Canada, Demantoid garnets from Russia are United States, Burma and China. well known, and celebrated for their Malaya: Tanzania. characteristic “horse-tail” inclusions that often radiate throughout the Pyrope: Austria, Czechoslovakia gemstones. (the classic source in the 1800s), South Africa and United States. Rhodolite: Sri Lanka, Tanzania, Zimbabwe, Madagascar and United States. Spessartine: Brazil, Sri Lanka, Nigeria, Kenya, Tanzania, Australia, India, Madagascar, United States.

25 CIBJO Retailers’ Reference Guide May 2010 Gemstones Jade

Jadeite & nephrite “The wise liken jade to virtue. Its polish Jade on the calendar and brilliancy represent purity. Its extreme Jade is a blanket term used to describe Jade is considered a 12th anniversary hardness is intelligence. Its angles, which a metamorphic mineral group that gemstone. do not cut, although they seem sharp, are comprises two separate species of gem: justice. The pure and prolonged sound, jadeite jade and nephrite jade. The name What jadeite & nephrite are which it sings when one strikes it, are music. for jade (as it is known in the West) Its colour is loyalty. Its iridescent brightness Jadeite jade is composed of the following comes from the Spanish piedra de hijada, represents heaven.” minerals: NaAlSi O . Nephrite has the referring to the stones’ shape as they were 2 6 following composition: Ca (Mg,Fe) found, resembling kidneys. In China, where When jadeite jade was discovered in 2 4 Si O (OH) . appreciation and knowledge about both neighboring Burma (Myanmar) in the 18th 8 22 2 forms of jade far surpasses that of the Century, it became an immediate success Colour(s): West, and has since approximately 5000 in China as well. Enthusiasts of jadeite Jadeite jade: Appearance is semi- B.C., the word for nephrite jade is yu. It jade appreciate its vivid variety of colours transparent to opaque often with mottled is often said that in China, the value and including red, orange yellow, green, violet colours in white, green, yellow to reddish appreciation for jade surpasses that of (lavender) and black. (Note: while blue orange, brown, grey, black, light purple. gold and other valuable minerals. What jade is not found in Burma, very small the Chinese valued in nephrite jade was and rare quantities of blue Guatemalan Nephrite jade: Transparent to opaque, its incredible toughness; as such the gem jadeite jades have been found.) In Central creamy, often with mottled colours in was often carved into statues, sculptures, America, one of the other historic sources light to dark green, yellow to brown, white, hollowed beads, bowls and weapons. of jadeite jade, the Mayas and Aztecs grey, black. The Chinese philosopher Confucius, who appreciated the gem for its hardness and Refractive Index: was born five centuries before the birth colours as well. Today, deep colour and of Jesus, appreciated jade as well, and is relative transparency are the yardsticks Jadeite jade: 1.666 to 1.680 (+/-0.008) widely quoted in regards to the gem: by which both jades are measured – but Nephrite jade: 1.606 to 1.632 deep uniform green translucent jadeite (+0.009, 0.006) sometimes referred to as “Imperial jade” gemstones, are especially coveted.

26 CIBJO Retailers’ Reference Guide May 2010 Gemstones Jade

Birefringence: Jade’s treatments Dyeing: Dyeing of some jadeites follows bleaching treatments, using various For more information about CIBJO standards Jadeite jade: Usually not detectable In jadeite jade: colours. Some colours may fade over and rules regarding treatments, artificial and Nephrite jade: Usually not detectable Wax Impregnating: Jadeites are sometimes time, especially exposed to strong light imitation products, or synthetic stones please cleaned in acids and neutralizing solutions, sources. As a final step, some jades are then download a free pdf copy of the CIBJO Specific Gravity followed by boiling in water to clean off polymer impregnated to make them appear Coloured Gemstone Bluebook: www.cibjo.org Jadeite jade: 3.34 (+0.06, -0.09) any residue. Following this they are dipped homogenous. Such treatments result in in wax as part of the polishing process. jadeites that are sometimes refrerred to Nephrite jade: 2.95 (+0.15, -0.05) The wax enters tiny fissures and pits in the as “C” jadeites in the trade. Cause(s) of colour: In green jadeite: jadeite, giving the gem a more uniform Heating: Some jadeites are heated in an chromium (and /or iron). Iron is the main appearance. Purely natural jadeite and effort to change their colour. Heating cause of colour in lavender, orange and some which have been slightly waxed may lighten some overly dark greens or brown jadeite. In nephrite jade, iron is the during polishing are sometimes referred cause yellow staining to turn a deeper cause of many colours. to as “A” jadeites in the trade. reddish colour. Hardness: on the Mohs Hardness Scale: Acid Bleaching / polymer impregnation: In nephrite jade: Here jadeites with stained surfaces are Jadeite jade: 6.5 to 7 hardness; submerged in acids with the aim of Dyeing: Some nephrite jades may be toughness is exceptional. bleaching the stains. The treatment causes impregnated with dyes to improve Nephrite jade: 6 to 6.5 hardness; toughness such jades to become more porous; a the colour – though the treatment is is exceptional, exceeding that of jadeite. subsequent polymer resin impregnation considered rare. renders the jadeite more evenly coloured Internal identifying characteristics: Paraffin impregnation: Some nephrite may and translucent. Treatments with acid treated with paraffin to conceal surface Jadeite jade: mottled colours, a granular followed by polymer resin impregnation irregularities (such as cracks or fissures) in (sugary) appearance in cracked or are sometimes refreed to as “B” jadeites the gem. Jadeite jades occur in a variety of colours, unfinished areas of a gemstone. in the trade. though by far the most coveted is “imperial Heating: Some heating results in the jade,” a vivid green, nearly transparent or lightening of overly dark colours of nephrite. translucent gem such as the smallest jadeite cabochon shown here.

27 CIBJO Retailers’ Reference Guide May 2010 Gemstones Jade

Collector jades Jade localities The cutting and care of jades Deep natural colour and the homogeneity Jadeite jade: The classic and most Both jades are considered extremely of the colour plays a large role in the important source of jadeite is Burma durable – even though they don’t rank as appreciation of jadeite jade. Deep green, (Myanmar), and it remains the principal very hard on the Mohs Hardness Scale. translucent jadeite is revered, but apple producer of the gem today. Another This is because of their extremely compact, green jades are also highly appreciated. commercial source is Guatemala, though fibrous and granular structures. Both Lavender jades are also popular and rare, production is not as sustained as the Asian forms of jade are vulnerable to strong while yellow, orange and greyish jades source. Russia and Uzbekistan are also acids and heat. However, assuming the may contain unique symbolic meaning considered sporadic sources of jadeite. colour is natural and untreated, both jades that is linked to their colour. While solid Significantly, Burmese jade remains the are safe for steaming and immersion in colours in a gem are always appreciated, classic standard by which other jadeites an ultrasonic cleaner. If it is not known mottled streaks of colour or a combination are compared. whether the gem was treated, a soft bristle of colours might be perceived as symbolic; toothbrush or damp, non-abrasive cloth Nephrite jade: China is the classic source obviously these are highly coveted. should be used for cleaning. for nephrite jade, but it is found on almost Nephrite jades with strong natural colours all continents. Other important sources are as well as materials that are carved into Canada, New Zealand, United States, Russia symbols are meaningful to collectors. and Australia. So too are sophisticated carvings. Because of the durability of both forms of jade, clever carvings that exhibit a three- Mottled jadeite jades, where two or Nephrite jade is extremely tough and dimensional object (such as a hollow bead more colours can be seen, are often durable. Aside from fashioning it into in which jade material had to be carved used in carvings. Carvings were (and gems for traditional use in jewellery, it out) are also objects of desire. are) often Chinese in origin because can also be fashioned into extremely China has a long history of appreciation intricate, pierced carvings. Nephrite has for nephrite and jadeite jades. a long history of appreciation in Asia where it was once considered more valuable than precious metals.

28 CIBJO Retailers’ Reference Guide May 2010 Gemstones Kunzite

Appreciation for kunzite a source for lithium which was often What kunzite is used for industrial purposes. Certainly Delicacy and subtlety of colour is this Kunzite is a variety of the spodumene spodumene, as it had been found till then, gem’s most notable attribute, making it an species. It forms in the monoclinic crystal hardly qualified for use as a gemstone. But excellent choice for eveningwear, where its system and is composed of LiAlSi O the delicate lilacs and deep purples, which 2 6 understated pink to lilac colour flashes can approached the beauty of amethysts, Colour(s): Light in tone, pink to bluish be divined and admired even at a distance. definitely classified kunzite as a gem. purple. Rarity also lends this gem an added sense Kunzite has since been found in several of exclusivity. It is not widespread enough Refractive Index: 1.660 to 1.676 (+/- 0.005) other localities around the world. Together to be known by all gem aficionados, but with hiddenite (a greenish variety found in Birefringence: 0.014 to 0.016 those who have developed a passion for it Hidden, North Carolina), it is a gem variety are quick to extol its virtues. Kunzites, while Specific Gravity: 3.18 (+/- 0.03) of spodumene. rare, may still be found as large crystals Cause(s) of colour: Manganese and as such are excellent candidates for Kunzite on the calendar jewellery designs that feature large and Hardness: 6.5 to 7 on the Mohs Hardness impressive centre stones. This gem was Kunzite is not on the calendar as a Scale. first discovered near Pala, in California’s particular birthstone, though Kunz Internal identifying characteristics: San Diego County in 1902. Crystals were patriotically suggested kunzite as an Kunzite rarely has inclusions, but being sent for identification to America’s top gem alternate American birthstone for the of pegmatitic origin, sometimes has a expert, George Frederick Kunz, a notable month of September, in his book The few liquid inclusions. However kunzite jeweler, author and gemologist based at Curious Lore of Precious Stones (1913). has perfect cleavage, meaning it has Tiffany & Co at the time. In a report about directional planes of atomic weakness the new gem, Kunz wrote: “As this is an that are prone to parting. entirely new gem of a peculiar beauty, a name will be given to it as soon as its characteristics are definitely determined.” Of course the gem was soon named after him. It was also determined that the gem belonged to the spodumene species,

29 CIBJO Retailers’ Reference Guide May 2010 Gemstones Kunzite

Kunzite’s treatments Kunzite localities Kunzite has a delicate lilac colour that has many devotees. The gem is considered Irradiation may produce pink or deeper United States (the classic source), quite rare as it is only found sporadically pink colours from colourless to pink Afghanistan, Burma, Brazil and Madagascar. at a few sources around the world. varieties of spodumene. Kunzite’s colour, including irradiated colour, is The cutting and care of kunzites susceptible to fading upon prolonged Kunzites are often fashioned as large, step exposure to light. cut gems and rarely carved because of their directional cleavage. Care must be For more information about CIBJO standards taken, especially with gems set in rings, and rules regarding treatments, artificial and because they tend to absorb the most imitation products, or synthetic stones please physical impact. Kunzites should not be download a free pdf copy of the CIBJO placed in an ultrasonic cleaner. It is best Some kunzites are prone to fading when Coloured Gemstone Bluebook: www.cibjo.org to clean them with a damp, non-abrasive exposed to bright lights, over long periods cloth. Because of their susceptibility to of time. Consequently, gemologists often fade upon prolonged exposure to bright recommend that kunzite jewellery be Collector kunzites light, kunzites are best placed in a dark stored in a dark container when not in use. storage container when not in use. Because kunzites are often thought of as uniquely American gemstones (though they are also mined elsewhere), gems from the Pala district possess a unique provenance, especially since they were named after a famous American. Depth of colour, especially in rich magenta coloured gems, is appreciated.

30 CIBJO Retailers’ Reference Guide May 2010 Gemstones Lapis lazuli

Appreciation for lapis lazuli Interestingly, the material was long What lapis lazuli is described as sapphir, though what was Technically, the gemstone lapis lazuli is A rock composed primarily of lazulite, known as sapphir in ancient times was a rock since it is an aggregate of more calcite and pyrite. It may also contain probably lapis lazuli – and not sapphire. than one mineral. But, what a rock! Lapis haüynite, sodalite, and diopside. Even Pliny the Elder used the word lazuli’s intense blue colour, at times sapphir in describing a blue gemstone Colour(s): Medium to dark, slightly flecked with white calcite and golden with golden spots. It is important to greenish blue to purplish blue, often coloured pyrite crystals, has captivated bear in mind that, as far as gem colours containing metallic looking pyrite crystals people’s attention for thousands of was concerned, lapis lazuli was the blue and/or white to grey flecks of calcite years. The Assyrians and Babylonians gem to covet and cherish, long before inclusions. prized lapis lazuli for use as carved seals. blue sapphires came to be appreciated. It was used throughout many of Egypt’s Refractive Index: 1.50 or 1.67 (with lots Today, lapis lazuli is valued as a bold dynasties, and was referred to by them of calcite) It can be challenging to obtain ornamental gem that can be beaded, as “heaven’s stone.” Pharaoh Cleopatra a refractive index reading for lapis lazuli. fashioned into cabochons and carved. VII had a particular affinity for it; aside Birefringence: None from using it in jewellery and as an inlay Lapis lazuli on the calendar for artifacts, she had it ground into a Specific Gravity: 2.75 (+/- 0.25) powder, which could then be emulsified While lapis lazuli is not mentioned as (This may vary due to mineral content) for use as eye shadow makeup. It was a birthstone in modern lists, it was Cause(s) of colour: In lazurite, used as a pigment (called ultramarine) once suggested as an alternate gem sulfur-related colour centres. for many centuries thereafter. It is for the month of December, together thought that lapis lazuli was one of with turquoise. It is considered a 9th Hardness: 5 to 6 on the Mohs Hardness twelve gems that comprised the Jewish anniversary gemstone. Scale; it varies due to impurities. high priest’s breastplate – during the Internal identifying characteristics: Exodus from Egypt. Lapis Lazuli, which randomly scattered pyrite crystals (that has long been mined in Afghanistan in appear as yellow metallic flecks) and an area traveled by merchants along mottled white calcite crystals. ancient Silk Road, spread appreciation for the blue gem in the Far East as well.

31 CIBJO Retailers’ Reference Guide May 2010 Gemstones Lapis lazuli

Lapis lazuli’s treatments Collector lapis lazuli The cutting and care of lapis lazuli a. Dyeing – Lapis lazuli, which is naturally Lapis lazuli that is naturally deep and This gem is generally cut in the form of porous, is easily dyed to deepen the uniformly blue in colour, is the most cabochons or tablets, and these kinds of colour and give the stone a more collectible form of the gem. Care must cuts wear well since they have no sharp uniform appearance. be taken to determine if the material edges to abrade. Beads also wear well has been dyed. If so, it is not considered for the same reason. Free form cuts and b. Paraffin coating or impregnation collectible quality. Some collectors carvings are also popular with lapis lazuli. – This treatment sometimes follows appreciate a discreet spray of pyrite A soft damp cloth is ideal for cleaning the dyeing in an attempt to seal the gem crystals, which serve as further proof gem and because the gem is naturally surface, continue to deepen the colour of the gem’s natural origin, though porous, it should be kept away from and help improve its polish. calcite’s mottled white flecks are not substances that could permeate the gem’s Unevenly coloured lapis lazuli is often c. Oiling – Some lapis lazuli may be as well appreciated. Because of lapis surface. Nail polish remover (acetone) and used for carvings, whereas pure, deep treated with oil in an attempt to lazuli’s ancient past, jewels with known other chemicals my harm dyed lapis lazuli. blues are reserved for use in fine jewellery, deepen its colour. provenance are considered collectible. much like these square cabochons are. Carvings, seals and intaglios that have been fashioned by known artists are also For more information about CIBJO standards collectible. Lapis lazuli has been admired and used and rules regarding treatments, artificial and for thousands of years. It is extremely imitation products, or synthetic stones please Lapis lazuli localities versatile and can be carved into spheres download a free pdf copy of the CIBJO (or beads), tablets or even faceted gems. Coloured Gemstone Bluebook: www.cibjo.org Afghanistan’s mountainous Northeastern area of Badakshan is the world’s most famous locality. It still produces the standard qualities by which other sources Examined up close, it is easy to see why are compared. Deposits in Iran, Chile and lapis lazuli is considered a composite Russia produce lighter, less saturated stone: the white parts are calcite; the varieties of lapis lazuli. metallic golden flecks are pyrite crystals and the deep blue colour is lazulite.

32 CIBJO Retailers’ Reference Guide May 2010 Gemstones Opal

Appreciation for opal His enthusiastic observation was that, the gem – especially black opal – is in fact compared to a diamond costing him perceived as lucky. Australian aborigines, The name opal derives from the Latin thirty three times as much, the opal had for example, attributed opal’s discovery word opalus as well as the Greek word brought him much greater pleasure. Part with the simultaneous, and fortuitous opallios. The words refer to a person’s of his enchantment may have been that discovery of how fire can be tamed and ability to perceive a change of colours. one opal never looks like another because utilised to cook food. These concepts form opal’s principal play-of-colour patterns change from gem features: their phenomenal nature and While fiery colours – and play-of-colour to gem. Like the people who wear them, extraordinary range of hues. In the has always been opals’ principal asset, each opal is unique. numerous phenomenal varieties of opal, they can also be colourless, composed many spectral colours can be enjoyed Other writers have invoked opal as well. of a single bodycolour, or be opaque, within a single gem. It is this colourful Shakespeare alludes to the changeable translucent or transparent. complexity about opals that caused nature of opal in his play, Twelfth One characteristic of opal that is not naturalist, Pliny the Elder– in the first Night, when he contrasts the versatile always as appreciated, as it should century AD, to write following: personality of one of its characters to be, is the ability of opal to form as a the gem. He also described opal as “the “There is in them a softer fire than the ruby, pseudomorph. In the case of opal, this queen of gems.” there is the brilliant purple of the amethyst, literally means the substitution of another and the sea green of the emerald, all shining Opal’s phenomenal nature has clearly mineral or substance with opal material. together in incredible union. Some by their brought enjoyment to many, but it has As such, opals may form as fossils in clam splendor rival the colours of the painters, also evoked unwarranted superstitions. shells, snail shells, bones, trees or tree others the flame of burning sulfur or of fire Because of a work of fiction by Sir Walter branches, and in the hollow inside joints of quickened by oil.” Scott, written in the 1800s, attributing bamboo stalks. Here, the opals take on the “enchanted powers” to an opal, some outward appearance of the item they have In 1550, Italy’s brilliant mathematician readers mistakenly began to think of replaced! However, most opals generally and naturalist, Girolamo Cardano, noted opal as an unlucky gem. In the century form in seams or cracks within harder rocks in his monograph, De Subtilitate Rerum, elapsed since then, opals have regained such as sandstone or basalt. (The Subtlety of Things), a study of their rightful reputation as an adaptable natural phenomena, that he had once gem of beauty. In Australia, where the vast bought [an opal] for fifteen gold crowns. majority of the world’s opals are mined,

33 CIBJO Retailers’ Reference Guide May 2010 Gemstones Opal

It is not surprising that there are several Contra-luz opal – is a transparent opal Black opals are those which exhibit dozen types or varieties of opal, not all shows play-of-colour when light is extraordinary play-of-colour against a of which can be described here. The main reflected or transmitted through it. Many dark background. In this extraordinary commercial varieties are: Mexican opals show this characteristic. Australian black opal the play-of- The words contra luz literally translates colour is so pronounced that the gem’s White opal – is translucent to semi to “against the light.” bodycolour is not discernible. translucent opal, with play-of-colour, against a white bodycolour. Boulder opal – is an opal seam naturally attached to the sandstone matrix where Black opal – is translucent to opaque opal, it formed. These can be very thin but still with play-of-colour, against black, grey, exhibit extraordinary play-of-colour. blue, green or brown bodycolour. Moss opal – is an opal containing Crystal opal – is transparent to dendrite inclusions of another mineral semi-transparent gem opal that has that cause a moss or fern-like appearance an essentially colourless bodycolour. within the gem. However, the colour we perceive is through the play-of-colour phenomenon. Oolitic opal – is an opal containing dark black or brown spherical inclusions that Fire opal – is transparent to semi look like fish roe in appearance. White opals are those that exhibit transparent opal with a range of light play-of-colour against a white or light yellow to deep orange bodycolour. Hydrophane – is an opal that appears grey bodycolour. These gems may have play-of-colour as common opal when dry, but which or none at all. develops play-of-colour phenomena when immersed in liquid. Jelly opal – (also called water opal) is transparent to semi transparent, and exhibits no play-of-colour.

34 CIBJO Retailers’ Reference Guide May 2010 Gemstones Opal

Opals on the calendar Colour(s): Many colours are seen in opal. Cause(s) of colour: Light diffraction Body colours can vary from white to dark affects from tiny irregular spheres of Opals are birthstone for the month of blue and to black, with brown, red orange silica, causing the colours we see in the October. Opals are also considered gifts in between. In recent years, a turquoise play-of-colour of an opal. If the body to commemorate 14th anniversaries. blue and a pink opal variety, owing their colour is green, it is caused by traces colour to traces of copper, has been of nickel impurities. What an opal is discovered in Peru. A milky, green opal Hardness: 5 to 6.5 on the Mohs Opals are part of a mineral species with found in Tanzania is called prase-opal due Hardness Scale. an amorphous structure, composed of to its similarity to the chalcedony variety the following elements: SiO2nH2O. The of prase. Because these gems have no Internal identifying characteristics: composition of opals is up to 20% water. play-of-colour, but are attractive for the Occasionally, small amounts of matrix can Tightly packed and arranged, microscopic body colour they exhibit, they are often be seen through thin seams in boulder spheres of silica, of which opal is faceted or cut as cabochon gems or beads. opal. Consequently, opals often contain composed, cause play-of-colour. Light Play-of-colour is an optical phenomenon elements of the environment in which they reflecting off and passing through these independent of the gem’s body colour that formed. Pyrite, hematite and other minerals spheres, frequently causes interference can include all spectral colours in unison. may occur as stain plumes or tiny, included and diffraction of light, which we are Opal may be transparent to opaque; most crystals. Two and three phase inclusions are able to perceive as play-of-colour. This opal is translucent. rare but may occur. Cristobalite inclusions phenomenon may be compared to are common in Mexican opal. Refractive Index: 1.450 (+0.020, -0.080) rainbows, which form as light passes Mexican opal my have lower readings, through water droplets in air. So while (1.37 to 1.43) opals may be essentially colourless, they can still have play-of-colour that is Birefringence: None revealed as the gem catches the light. A growing popularity of boulder opal from Specific Gravity: 2.15 (+0.08, -0.90) Australia is because thin seams of opal against a dark ironstone matrix can exhibit vivid play-of-colour. Such gems can be cut to include the ironstone as a form of natural backing to the opal seam.

35 CIBJO Retailers’ Reference Guide May 2010 Gemstones Opal

Opal’s treatments Opal doublet (or triplet) – While not Collector opals Localities for opals within the classic definition of treatments, There are many kinds of treatments that Collectors prize one-piece opals (without Australia produces well over half of the doublets constitute a man-made measure opals are subjected to. Most are designed matrix or backing) that display strong world’s opals, and some of the finest come taken to make thin seams of opal usable to “stabilize” the gem, or deepen the play-of-colour. Collectors look for from a locality called Lightning Ridge. In in jewellery. A doublet is a thin, natural colour, or cause the play-of-colour to patterns such as “harlequin,” which the 1950s L. Hudson, a postmaster for the opal slice that is glued to a strong black stand out against a darker body colour. shows a broad flash of colours when region, wrote a poem describing the area, substrate, such as dyed black chalcedony. the gem or light source is moved; part of which follows: a. Impregnation with oils, wax or Some glued slices are then capped with “pinfire,” which exhibits tiny flashes of plastic – this treatment may improve transparent quartz cabochons in an There’s a sleepy little township, multi-colour patches. White opals can play-of-colour and mask the effects of effort to protect the thin seam of opal. out beyond the western plains, also show these characteristics. Contra- crazing. Two separate materials glued together luz opals are also collected because of Lightning Ridge, the town of opal, are called doublets. If a third cap is also b. Dyeing – this treatment causes lighter their relative rarity, and because of their where there’s heat and scanty rains. used, it is considered a triplet. These opals to look like darker, black opals, dramatic reactions to light. There are “combination” gems may also exhibit The location is not scenic, which are considered more valuable. collectors of opal nodules from Yowah, an strong displays of play-of-colour. just rough ridges all around Australian locality. “Yowah nuts” are highly c. Smoke impregnation – this creates contrasting, large roundish opals, which Nature sired her scenes of beauty, the appearance of black opal. For more information about CIBJO standards formed within dark ironstone matrix. in black opal, underground. d. Reflective foil-backing– this and rules regarding treatments, artificial and In fact there is a growing appreciation Several other Australian localities: treatment darkens the gem and imitation products, or synthetic stones please for boulder opals, due to their strongly Coober Pedy, Andamooka, Yowah and improves play-of-colour. When the download a free pdf copy of the CIBJO contrasting hues and play-of-colour. Pink, Koroit produce opals as well. Opals opal is in jewellery, foil backing is not Coloured Gemstone Bluebook: www.cibjo.org blue and green opals are rare and therefore have been found in the United States, immediately evident. collectible as well. Mexico, Brazil, Peru, Kenya, Ethiopia e. Black paint backing – this treatment and Indonesia. works in similar fashion to foil backing by darkening the gem and improving the effects of play-of-colour.

36 CIBJO Retailers’ Reference Guide May 2010 Gemstones Opal

The cutting and care of opals Opals from Mexico include common opal, fire opal, jelly opal. These gems may Because opals have varying degrees of exhibit strong bodycolour with moderate water content, they are delicate – especially to intense play-of-colour. when subjected to heat, temperature changes, changes in air pressure (such as in an airplane). Opals may develop a network of tiny fissures over time, or if subjected to heat or pressure. These fissures are referred to as “crazing” in the trade. Because opals are delicate, they require gentle, loving Fire opal, such as these gems from Mexico, care in order to last a lifetime. Opals are sometimes are appreciated solely for their rarely faceted because the facet edges and intense yellow to reddish body colours. junctions are prone to abrasion. Most are Such gemstones are often faceted. cut en cabochon, which avoids abrasion along stark edges. (Some Mexican, Peruvian and crystal opals are faceted and these tend to exhibit a sleepy, milky appearance on colourless or coloured bodycolour). Cabochons are also an appropriate canvas upon which to best exhibit an opal’s play- The jelly opal and contra-luz opal shown of-colour. Dampened soft fabrics with no here exhibit strong play-of-colour. abrasive or chemical additives, or a soft The gem on the right exhibits play-of- bristle toothbrush doused with water are colour when light is directed at the the best ways to clean opal jewellery. Some gem and also when light is transmitted gemologists advise storing opal in a damp through the gem. environment – or even in a submerged in water, to avoid crazing.

37 CIBJO Retailers’ Reference Guide May 2010 Gemstones Organic gems

Appreciation for organic gems remain the single largest organic product the creamy soft texture of elephant ivory, that humankind enjoys in jewellery today. there are substitutes, such as ivory nut People have adorned themselves with gem As jewellery products, cultured pearls come palms, (also called tagua nuts) that are materials long before recorded history in many shapes, textures and colours, and obviously organic as well; many believe this began. Prehistoric people probably did so are easily put to use in design concepts. In material has the look and feel of animal with organics to begin with – because recent years, the explosion of technology in ivory. Tortoise shell falls under the same so many such materials were likely a side freshwater cultured pearl growth, mainly in endangered species conventions. product of hunting, fishing and gathering China, has added greatly to the choices that during human evolution. Finally, it should be noted that several other jewelers have. Conversely, the use of coral – though rarely used – organic materials are There is great appreciation for such and tortoise shell in jewellery is diminishing sometimes used in jewellery, though they gemstones, even today, because of this tie over time, due mainly to a growing will not be discussed in this Guide. These to life, and also because of the inherent movement to protect and safeguard marine include: rhinoceros horn, hippopotamus beauty of the gems. As an example, amber’s environments. tooth, hornbill, boar, narwhal tusk, and deer heritage as a fossilised tree resin, results in A similar principle has curtailed the sale antlers. During the 17th and 18th centuries, the golden coloured gems we love today. of ivory since 1975, when international and through the Victorian era, a black It is treasured because it formed between conventions prohibited hunting of material called jet was used. It is a form 345 and 146 million years ago, when elephants and walrus – major sources of lignite coal found in Whitby, England. dinosaurs roamed the earth and humanity of ivory tusks. There was (and remains) Because jet is a fossil derived from decaying did not yet exist. Ancient Greeks believed a growing recognition of the need to wood, it is considered an organic gemstone. that amber gems were tears shed by the protect these animals – particularly African Queen Victoria famously used jet jewellery gods, while others believed amber to be elephants – from herd decimation through in mourning. Human hair, also an organic fragments of the setting sun. Entrapped illicit poaching. A huge ivory industry substance, was also woven and set in insects and other animals occasionally existed from the mid 1800s to the mid jewellery during the Victorian Era. found in amber dispelled those notions. 1900s, when people appreciated ivory Today, such inclusions are sought after [Note: The information about cultured pearls has carvings, inlays, jeweled accents, piano keys, and prized because they offer a fascinating been abbreviated here, since an entire section bead necklaces, billiard balls and handles. glimpse into a vanished world. Humans are about pearls is contained in the CIBJO Retailers’ That industry is a miniscule fraction of what equally linked to the oceans through pearls, Reference Guide.] it once was. Luckily for those who treasure corals and tortoise shells. Cultured pearls

38 CIBJO Retailers’ Reference Guide May 2010 Gemstones Organic gems

Organic gems on the calendar Birefringence: Cause(s) of colour: Hardness: Of the organic gems, only natural or Amber: (none) Amber – (may be seen in yellow, orange Amber: 2 to 2.5 on the Mohs cultured pearls feature on the calendar. and brown colours and rarely as blue and Hardness Scale Cultured Pearls: (0.155) Pearls are the birthstone for the month green.) Impurities and organic substances Cultured Pearls: 2.5 to 4 on the of June, and the feature as a choice for Coral: 0.172 cause colours in amber. Green and blue Mohs Hardness Scale both the 3rd and 30th anniversary. ambers are so perceived due to strong Tortoise shell: (none) fluorescence in some amber from the Coral: 3.5 to 4 on the Mohs What organic gems are: Ivory: (none) Dominican Republic. Hardness Scale Straightforwardly defined, organic gems Conch pearls: 0.155 Cultured Pearls – pearls are composed of Tortoise shell: 2.5 on the Mohs are those whose compositions were once tightly overlaying organic platelets that Hardness Scale Specific Gravity part of a living organism, coming from cause us to see various colours as a result Ivory: 2.25 to 2.75 on the Mohs either the plant or animal kingdoms. Amber:1.08 (+0.02, -0.08) of light interference and diffraction. Hardness Scale Refractive Index: Cultured Pearls: 2.72 to 2.78 Coral – (Red, pink, orange, white and Conch pearls: 2.50 to 4 on the Mohs cream coloured.) Organic matter and Amber: 1.540 (+0.005, -0.001) Coral: 2.65 (+/- 0.05) Hardness Scale carotenoids cause the colour in corals. Cultured Pearsl: 1.530 to1.685 Tortoise shell:1.29 (+0.06, -0.03) Identifying characteristics: Tortoise shell – (Mottled brown and tan Coral: 1.486 to 1.658 Ivory: 1.70 to 2.00 with varying degrees of transparency.) Amber – two phase inclusions of gas and Organic elements cause the colour. liquid, flow lines, inorganic inclusions, Tortoise shell: 1.550 (-0.010) Conch pearls: 2.85 (+0.02, -0.04) insects and small animals such as lizards. Ivory – (Creamy white to slightly yellowish Ivory: 1.535 to 1.540 (usually 1.540) Heated amber causes some inclusions white) organic elements. to expand, causing spangled, disc-like Conch pearls: (a calcareous concretion Conch pearls – (pink to red) Caused by inclusions. found in conch shells) 1.530 to 1.685 organic molecules and various impurities. Cultured Pearls – slight gritty sensation when rubbed against the cutting edge of your teeth. (Imitation pearls are smooth.)

39 CIBJO Retailers’ Reference Guide May 2010 Gemstones Organic gems

Coral – Cavities from polyps, fibrous Tortoise Shell – Rarely tortoise shell is Collector organic gems Conch pearls – Conch pearls that are structure. dyed to produce a variation on mottled uniformly spherical or oval in shape, which Amber – Strong colours in amber are colour. Some tortoise shell may be contain deep pink to red colour and highly Tortoise shell – Mottled colouration. considered collector items, as is any amber laminated together through heat and visible “flame structure” patterns, are Numerous spherical particles are seen containing unusual insects. Entomologists pressure to make larger pieces. highly collectible. under magnification. seeking to understand a bygone world Ivory – Ivory is commonly bleached to often collect these amber samples for Ivory – Structured, parallel lines that Organic gem Localities lighten or remove stains, for a uniform further study. intersect, a so-called “engine-turned” colouration. This is sometimes followed Amber – Dominican Republic, Baltic Sea effect. Cultured pearls – Cultured South Sea and by a dye to give the ivory an “antique” (bordering Germany, Poland and Russia), Tahitian pearls or large size and unusual Conch pearls – flame like structure when appearance. Finally, ivory is occasionally Mexico. colour or orient are especially prized. There a bright light is directed at the pearl. impregnated with colourless wax. are some (though rare) faceted pearls Cultured pearls – Japan, China, South Conch pearls – None known. strands that are occasionally collected. Sea (Tahiti), Philippines, Australia, United Organic gems’ treatments Natural (not cultured) pearls are always States, Mexico. Amber – Heating in oil causes some collectible since they are rarely found For more information about CIBJO standards Coral – Mediterranean Ocean, (Algeria, cloudy amber to clarify, or to produce today. This is also true for antique jewels and rules regarding treatments, artificial and France, Italy, Morocco and Tunesia); darker amber colours. Amber is sometimes containing natural pearls. imitation products, or synthetic stones please Taiwan, United States, Mexico, Dominican dyed to add a darker tone to lighter download a free pdf copy of the CIBJO Coral – Large, fine coral carvings of rich pin Republic, Australia, Malaysia. materials. Coloured Gemstone Bluebook: www.cibjo.org to deep red colours are most highly prized Tortoise shell – Brazil, Caribbean, Pacific Cultured Pearls –Pearls are usually and very rare. Ocean, West Indies, East Indies, Indian bleached, dyed or irradiated (See section Tortoise shell – Antique hair ornaments Ocean, Malay Archipelago. on pearls for further information.) and combs, boxes and objects of art, Ivory – All African countries where Coral – Corals are commonly dyed or Ivory – Intricate delicate Fare Eastern elephants roam, Sri Lanka, Thailand, India. impregnated with epoxy like resins to carvings, cue balls, hair ornaments, fans fill surface cavities and/or to increase Conch pearls – Mexico, Dominican and miniature 17th Century Netsuke durability of the material. Additionally, Republic, South Pacific, United States. sculptures are collected. some corals are dyed.

40 CIBJO Retailers’ Reference Guide May 2010 Gemstones Organic gems

The cutting and care of organic gems

Most organic materials are fashioned as Avoid rough handling, heat and chemicals Amber is often prized for relics of the cabochons or rounded or free-form beads, for all organic materials. They are soft, ancient past they may contain, such as and are rarely faceted. Ivories may be occasionally brittle, and porous enough these insects and plants enveloped in carved into very delicate, intricate, detailed to be attacked by acids. Cleaning may be amber from the Jurassic period. carvings, and objects of art, particularly performed using a dampened cloth or a in Eastern Asia. While rings using organic moistened soft bristle toothbrush. Strung materials are used, the user must take pearls should not be soaked in water, as special care. this will cause the silk cord to stretch.

Extremely rare “conch pearls” are collected for their beautiful pink to reddish colours and their phenomenal “flame structure.” This effect is best seen when a bright light illuminates the gem.

Gems from the sea include organic treasures Organic gems found on land include such as the tortoise shell (top and butterfly ivory (top cabochon and carving), pin), the pink, white, purple and red coral vegetable “ivory,” or tagua nut carvings and necklaces, and the trio of (bottom right), jet (bottom), cultured pearls. and amber.

41 CIBJO Retailers’ Reference Guide May 2010 Gemstones Peridot

Appreciation for peridot Even so, peridot has even been found Specific Gravity: 3.34 (+0.14, -0.07) in meteorites, suggesting that another For anyone who loves hazy, yellowish green Cause(s) of colour: traces of iron continent like our own is not out of colours, peridot is sure to be appreciated. impurities. the realm of possibilities somewhere in At its best, the gem exudes a soft, oily space! Hardness: 6.5 to 7 on the Mohs Hardness appearance; comparable to the deep Scale. greens you might see in a glass of olive The source of the name is thought to be oil. In ancient times, peridot was described Arabic, deriving from the word faridat, Internal identifying characteristics: as a gem “containing rays of sunshine.” meaning gem. However, French and 13th Inclusions of biotite mica, chromite and It is easy to see why: in direct, brilliant Century English root words have also biotite in the gem often cause internal sunshine, peridot often returns a warm, been suggested as the name derivation stresses to occur. In turn, these stresses yellowish glow to the eyes. Additionally, for this gem. cause liquid filled discoid fractures peridot has very high double refraction (or known as lily pad inclusions. birefringence), causing an optical effect in Peridot on the calendar which a doubling of pavilion facets often is Peridot’s treatments Peridot is the birthstone for August. It is observed when looking through the table of also a 15th anniversary gemstone. None known. the gem; this feature accentuates peridot’s soft, velvety look. What peridot is Collector peridots Peridot is a variety of the mineral olivine, Peridot is an olivine mineral that forms With peridots, locality, colour and size and has been treasured as a gem for in the orthorhombic crystal system and are the significant aspects to consider. thousands of years. Egyptian slaves are is composed of the following elements: Gems that can be proven to come from said to have discovered the first source (MgFe) SiO . Zabargad (also called St John’s Island) are for it at Zabargad, a desolate island in 2 4 rare since that classic deposit has been the Red Sea. Zabargad is considered the Colours: yellowish green to greenish largely depleted. Burma (Myanmar) and, classic source for the gem, though it no yellow to brownish green more recently, Pakistan are sources that longer produces commercial quantities. Refractive Index: 1.65 to 1.69 continue to provide exceptional gems of Luckily, the mineral olivine occurs on significant size, often over ten carats. every continent. As a transparent, bright Birefringence: 0.035 to 0.038

green gem, peridot is much more elusive.

42 CIBJO Retailers’ Reference Guide May 2010 Gemstones Peridot

Because peridot is plentiful, collectors The cutting and care of peridots often opt for size (ten carats or above) Because peridot is not an extremely hard with saturated, slightly yellowish green gem, ultrasonic cleaners are not an ideal colours. Cutting has become an important Very large peridots may occur at way to clean peridot jewellery. Peridots factor as well: well balanced gems that sources around the world, though are also susceptible to extreme heat, so efficiently return colour and light, together they are not common in deeply steamers should not be used. Certain acids with crisp facet junctions, are always coloured, exceptionally clean gems used in jewellery manufacturing may etch appreciated. On extremely rare occasions, such as this one. peridot, so it is recommended they not a star peridot (sporting 4 rays) is reported. be used around this gem. Finally, a soft, damp cloth, or a soft bristle toothbrush Peridot localities is probably best to use when cleaning Egypt (St John’s Island) is the classic peridot jewellery. The characteristic colour of peridot source, though it is no longer a commercial ranges from a grassy green to a softly producer of the gem. Burma is considered hazy yellowish green. a classic source too, if only because it has consistently produced large, clean peridots, which have become a global gauge to measure this gemstone’s beauty. In recent years, Pakistan has also become a producer of very fine material. The United States Crystals of chromite or biotite are consistently mines for the gem in the known to cause these characteristic, State of Arizona, though these peridots are discoid, “lily-pad” formations in peridot. generally smaller and sometimes slightly brownish in colour. Australia, Brazil, China, Kenya, Ethiopia, Norway, Sri Lanka and the Antarctic have also produced it, though not in significant commercial quantities.

43 CIBJO Retailers’ Reference Guide May 2010 Gemstones Unusual quartzes and chalcedony

Appreciation for unusual quartz The Ancient Greek word for ice is kristallos. jewellery in the late nineteenth century. and chalcedony In 1646, Sir Thomas Browne proved Since then the majority of brown quartz crystal quartz to be a mineral, rather than has been sourced in other localities around Were it not for gemological physical permanent ice. His book Pseudodoxia the world. There is also a small amount and chemical constants, multitudes Epidemica, described this as one of his of natural green quartz available, called of unique quartzes would certainly be corrections to “vulgar errors.” prasiolite. However, the majority of the appreciated as different gem species – green quartz available on the market today because they can look so different from Colourless quartz, or rock crystal quartz, is pale amethyst treated to turn green. one another. Quartzes can be colourless has long been cherished for its clarity or richly coloured, transparent or opaque, – references to the clarity of crystal Rose quartz is a semi transparent to highly included or not. They can exhibit emanate from ancient writings, including transparent variety of quartz whose chatoyancy, asterism, aventuresecence or the Bible. Some people have long believed devotees appreciate its soft, pink colour. iridescence. They can be as common as that gazing into a large rounded crystal It tends to be very lightly saturated and particles of sand on the beach, or deeply gave clairvoyants an ability to “see” when cut as a cabochon, and it occasionally coveted gems that are spirited into private the future. exhibits asterism in direct lighting. The star collections and insured at high values. effect is caused by light reflecting from Colourless quartz with bold and colourful The noted Swiss gemologist, Dr. Eduard tiny, oriented, included rutile needles that inclusions of another mineral (such as Gübelin, aptly referred to quartzes as the align themselves hexagonally during the tourmaline, hematite, mica or rutile are “jack of all trades.” Yet it is found on every crystal’s formation. Stars and cat’s eyes increasingly used in jewellery.) Generally, continent on earth, standing in as one of occasionally form in smoky quartz and more colourful forms of quartz, such as the world’s most plentiful minerals. (rarely) in colourless quartz as well. amethyst and citrine, are predominantly In ancient times it was believed that used in jewellery. (For more about Aventurine is yet another quartz quartz was a form of permanent ice, amethyst see page 6; for more about that exhibits phenomena as a result a suggestion first offered by the natural citrine, see page 13). of its inclusions. Curiously, the term historian, Pliny the Elder. This belief “aventuresecence” is named after an Closely related to citrine is a brown evolved from what was once a major Italian glassmaker who accidentally tipped coloured gem, called smoky quartz. It was source for quartz: the snow and ice- copper filings into a batch of molten found in the Cairngorm Mountains of covered Alps. The word crystal in fact glass. The result of his fortuitous accident Scotland and extensively used in Scottish derives from this mode of thinking. was a glittering form of man-made glass.

44 CIBJO Retailers’ Reference Guide May 2010 Gemstones Unusual quartzes and chalcedony

His colleagues remarked he had found Chalcedony is a significant and historical • Bloodstone – A dark green chalcedony • Iris agate – Semi transparent to it “per avventura,” or by chance. The form of quartz; a family with dozens of with deep red spots. translucent, exhibiting phenomenal name stuck. Aventurine glass, which is varieties and colours. Chalcedonies have iridescent colours when light, especially • Carnelian – Semi transparent to still manufactured and faceted in Italy, been enjoyed and used in jewellery for pinpoint lighting, is transmitted translucent yellow orange to orangy should not be confused with aventurine thousands of years. Some estimates through the gem. red or brownish orange gem. quartz. Aventurine quartz is green in gauge the use of chalcedony in seals and • Jasper – Translucent to opaque appearance and its aventurescent effect ornaments – as far back as the Bronze Age, • Chrysocolla-in-chalcedony – material, that may be any colour or is generally less pronounced than in glass. circa 1800 B.C. A more recent record for Translucent to semi translucent combination of colours – except black. Aventuresecence in quartz is due to the chalcedony dates back to the Israelites’ intense light blue or blue green, granular interlocking of quartz crystals, Exodus from Egypt. At least three varieties owing its colour to chrysocolla, • Onyx – Larger slabs with straight combined with flat, disc-like inclusions of of chalcedony were used in the Jewish a copper silicate. parallel layers of different colours and mica that produce glittering reflections High Priest’s Breastplate. (Moses’ brother degrees of translucency are sometimes • Chrysoprase – Translucent to semi in direct light. This optical effect is similar Aron wore the Breastplate, with inscribed referred to as onyx. translucent, light to medium yellowish to schiller – which is used to describe gems representing the twelve tribes of green. A slightly less saturated green • Sard – Semi transparent to translucent glittering reflections in sunstone. Israel). The Breastplate included jasper, material is referred to as “prase.” dark brownish red to brown or dark chrysoprase and sardonyx, and there is Rutilated and tourmalinated quartzes orange, but less saturated in colour some debate as to whether other agates • Dendritic Agate – Chalcedony (also called sagenitic quartzes) contain than carnelian. were also used. containing dark, branch-like or large, highly visible inclusions that tree-like inclusions. • Sardonyx – Semi transparent to become a celebrated part of the gem Here are some of the principal chalcedony translucent dark brownish red to brown itself. Rutile needles may be random, varieties used in jewellery today: • Fire agate – semi translucent to or dark orange, but less saturated in large and golden in colour, or may form opaque with iridescent phenomena • Agate – The word “chalcedony” is colour than carnelian, containing white in multi-rayed, star-like inclusions within against a brown bodycolour. sometimes used interchangeably with or black banded parallel layers. the gem. Drusy quartz is occasionally used the word agate, though agate generally • Landscape agate – A chalcedony in jewellery design. This is an overgrowth describes curved or angular-banded that contains trace impurities of of minute quartz crystals over other varieties of chalcedony. other minerals that cause unusual larger specimens, or matrix. The result is a colour combinations, which resemble glittering, rugged texture that is kept in its • Amethystine – Semi translucent landscapes. rough form and mounted in jewellery. to opaque purple colour.

45 CIBJO Retailers’ Reference Guide May 2010 Gemstones Unusual quartzes and chalcedony

Other quartzes and chalcedonies Refractive Index: Quartz: 1.544 to 1.553 Carnelian – Body colour due to iron Internal identifying characteristics: on the calendar Chalcedony: 1.535 to 1.539 impurities. Chromium may be present In transparent quartz varieties dendritic in redder colours. inclusions, and inclusions of other minerals Quartz: Rose quartz is sometimes Birefringence: Quartz: 0.009; such as mica, may be present (liquid regarded as an alternate birthstone for Chalcedony: usually not detectable. Chrysocolla – Colouration normally inclusions can be found in all varieties the month of January (along with garnet). due to impurities of copper. Specific Gravity:2.66 (+0.03, -0.02) of transparent quartz). There may be Chalcedony: Bloodstone (a variety of Chalcedony: 2.60 (+0.10, -0.50) Chrysoprase – Colouration normally colour zoning. In chalcedony there may agate) is an alternate birthstone for the due to impurities of nickel and/or iron. be inclusions of other minerals Cause(s) of colour: month of March. Onyx is suggested as and occasionally organic inclusions – Fire agate – Body colour due to iron a 7th anniversary gemstone. Rose Quartz – Titanium traces and/or such as shells. Thick bands of colour impurities. colour centres. often characterize chalcedony. Dendritic What quartzes and Sard – Body colour due to iron impurities. inclusions are seen in chalcedony as well. Smoky quartz – Colour centres involving chalcedonies are Chromium may be present in redder aluminum impurities. colours. Quartz and chalcedony are both mineral Aventurine quartz – The colour is caused species with the chemical composition Hardness: by the inclusions of fuchsite and mica of SiO . 2 platelets. Quartz: 7 on the Mohs Hardness Scale. Quartz grows in the hexagonal crystal Chalcedony: 6.5 to 7 on the Mohs system, whereas chalcedony is an Hardness Scale. aggregate material. Some chalcedony grows in a botryoidal formation.

Quartzes, other than the principal varieties of amethyst and citrine include (top row): rock crystal quartz, smoky quartz, rutilated quartz, rose quartz, rose quartz and ametrine. Bottom row: smoky quartz, rutilated quartz and praseolite.

46 CIBJO Retailers’ Reference Guide May 2010 Gemstones Unusual quartzes and chalcedony

Quartz and chalcedony treatments Chalcedony: Collector quartzes and chalcedonies Quartz: a. Dyeing – Chalcedony can be dyed in practically all colours, due to its porous Quartz: Rose quartzes and phenomenal a. Quench crackling – Heating, followed nature. Much of the black chalcedony quartzes are often collected with by immersion in water causes thermal sold on the market is dyed black. In emphasis placed on depth of colour shock and the gem develops cracks and banded material, some bands may be and strength of phenomena. Smoky fissures. This by itself is not attractive, dyed while others remain white. quartzes are collected in antique but it is followed by a dye impregnation jewellery – especially Scottish jewellery, to reach deep inside the quartz. The b. Heating – Some yellow to brown due to the historical aspects. result, for example, can make a gem material may be heat treated to result Fine needles in quartz can produce look surprisingly like emerald or ruby in redder colours. Chalcedony: Chalcedony exhibiting asteriation, such as the strong star (depending on the dye used). unusual banding or landscape scenes seen in this smoky quartz. are particularly prized, as are agates b. Irradiation – Colourless quartz can be For more information about CIBJO standards containing dramatic dendritic inclusions. irradiated to look smoky; rose quartz’s and rules regarding treatments, artificial and Iris agates and fire agates exhibiting colour can sometimes be deepened imitation products, or synthetic stones please strong iridescent colours are also through irradiation. download a free pdf copy of the CIBJO collected. Finally, carved chalcedony, such Coloured Gemstone Bluebook: www.cibjo.org c. Heat treatment – Heating may lighten as intaglios or cameos, may be collectible the colour of dark smoky quartz. if they have provenance that can be identified as typical of a certain era. d. Coating or foil backing – Deepens the Signed gems from a known lapidary colour of some gems. May help with artist are also collectible. cat’s eye or star phenomena. e. Dyeing – (Generally after quench This dendritic agate is highly collectible crackling) may cause the material due to the strong tree or branch-like to appear a totally different colour. patterns it exhibits.

47 CIBJO Retailers’ Reference Guide May 2010 Gemstones Unusual quartzes and chalcedony

Quartz and chalcedony localities Artists there carved local chalcedonies, but later began to import agate from Quartz: Germany, Hungary, India, Iran, Brazil as supplies dwindled in Germany. Brazil, Bolivia, South Africa, Madagascar, Mexico, Sri Lanka, Scotland, Spain, While quartz and agates are very durable Switzerland, United States. in general, special care should be taken with subjecting them to temperature Landscape agate such as this contain Chalcedony: Germany, Brazil, India, Russia, extremes. Quartzes may be cleaned in an impurities that result in interesting Australia, Austria, Scotland, Italy, Mexico. ultrasonic cleaner if it is clear and there colour patterns. are no fissures that could endanger the The cutting and care of quartzes durability of the stone. and chalcedonies Chalcedonies may be porous, so care Quartz: Skilled lapidary artists often must be taken not to immerse the gem carve rock crystal quartz into objects of in substances that could change its art, or in unusual shapes. Gems exhibiting appearance. As with most gems, a damp, phenomena are often cut en cabochon soft cloth, or scrubbing with a soft-bristle or tablet shapes. toothbrush, are the best ways to clean Chalcedony: Chalcedony is a gem these two forms of quartz. composed of cryptocrystalline (microscopic) quartz crystals that form in tightly interlocking, fibrous masses. This provides chalcedonies with Chalcedonies, forms of cryptocrystalline extraordinary toughness, allowing them quartz, include chrysoprase (the green to be carved in large flat cabochons, carving and cabochon), amethystine intaglios, cameos, tablets or even chalcedony, chrysocolla (the blue green plates or bowls. Idar-Oberstein, twin cabochon), and the carnelian beads. cities in Germany, have been known for developing the cutting and carving industry for this gem since the 1700s.

48 CIBJO Retailers’ Reference Guide May 2010 Gemstones Unusual quartzes and chalcedony

Banded agate, such as this Some chalcedonies contain impurities sardonyx, are often carved into that oxidize over time, resulting in beads, bowls or sculptures. highly collectible dendritic patterns.

Unusual varieties of quartz and Moss agates contain inclusions agate are this rutilated quartz that look like moss. The reddish cabochon (left), and this fire agate, orange colouration is due to trace which exhibits rounded formations impurities of iron. and iridescent colours.

49 CIBJO Retailers’ Reference Guide May 2010 Gemstones Ruby

Appreciation for ruby as well, with the old phrase “pigeon identified Ceylon (Sri Lanka) and the blood” sometimes used still to describe Kingdom of Pegu (Burma – or Myanmar Throughout humanity, red has represented a fine ruby. For some, red spinels come – today) as the main sources of ruby. In passion and romance. Ruby, the red close to be considered as equals, and in describing the perils inherent in hunting for gemstone of the corundum species, has a few interesting historical cases were gems, he notes that a voyage to Kyatpyen, been engaged for centuries to symbolize indeed thought to be rubies! The famous where rubies were traded, should not be those sentiments. 17th Century English Black Prince’s Ruby, a 170-carat gem attempted by land: “…on account of the poet, Robert Herrick, made allusion to that graces the Imperial State Crown jungles which abound with lions, tigers both passion and the gems’ colour when of England, nestled next to the famous and elephants,” he wrote. In 1904, traveler he wrote: Cullinan II diamond, is a case in point. V.C. Scott O’Conner described Thabeit-Kyin Some asked me where the rubies grew, Worn by successive Kings and Queens as the port of Mogôk, Burma’s famous And nothing I did say; since the 1300s (and even in helmets ruby and sapphire source: “Through this But with my finger pointed to going into battle) the gem was found, little postern gate the wealth of Capelan The lips of Julia. upon examination, to actually be a spinel. has passed for centuries on its way to That said, the differences between ruby the great world; to the treasuries of kings, Rubies are mentioned in the Bible – and and spinel were not always understood to the fingers of princes, to the necks of their value is clearly understood. The in antiquity, and red gems in general beautiful women; to the making of one, remark in Job, “The price of wisdom were often simply described as “ruby.” the undoing of another.” And this is exactly is above rubies,” is but one of several The Persian scientist, Abu Rayhan Biruni how locality fits into appreciation. Because references. Ruby was chosen to represent did classify differences between spinel Burma has produced a standard of quality one of the twelve tribes of Israel during and ruby gemstones in the 11th century, by which rubies from other localities are Exodus, and was worn on the Breastplate though his teachings did not make it into often measured, the term “Burmese ruby” of the Jewish High Priest. conventional thought until much later. has also come to be understood by many The word ruby comes from the Latin, in the trade as a quality designation. But Sources for rubies are as fraught with ruber, meaning red. While there are several designations of that kind require additional passion and romance as the gemstones red gemstones enjoyed by humankind, qualification, as Burma produces both high they produce. The French traveler and ruby is esteemed and regarded as the and low end quality rubies. merchant, Jean Baptiste Tavernier who very definition of red. Descriptions of traded in gemstones in the mid 1600s, ruby’s colour have wandered into passions

50 CIBJO Retailers’ Reference Guide May 2010 Gemstones Ruby

Appreciation for rubies has a historical Birefringence: 0.008 to 0.010 Ruby’s treatments For more information about CIBJO standards genesis in India, especially during the Specific Gravity: 4.00 (+/- 0.05) a. Heating – This treatment dissolves or and rules regarding treatments, artificial and rule of the Mughals in the 1500s, whose partially dissolves fine rutile needles imitation products, or synthetic stones please leaders –particularly Shah Jahan, had an Cause(s) of colour: Chromium with thereby increasing the clarity and download a free pdf copy of the CIBJO affinity for rubies and other gemstones. possible modifications of colour with transparency of the gem. In certain Coloured Gemstone Bluebook: www.cibjo.org These were often carved with verses from iron and titanium. cases, controlled heating helps re- the Qur’an and worn in turbans, articles Hardness: 9.00 on the Mohs Hardness define asterism in star rubies. It may of clothing and jewellery. The features of Scale. also help remove purplish or brownish Collector rubies ruby, which have always been appreciated, colour components in some gemstones, are those that help define the meaning of Internal identifying characteristics: Location, or provenance, is particularly resulting in stronger red colours. gemstone: rubies are beautiful; they are “Silk,” networks of fine, included rutile important with ruby. A fine ruby with a durable and they are rare. needles, intersecting at 60 degree angles, b. Diffusion – The diffusion of colour “Burmese” designation may be perceived are commonly seen in natural ruby. causing elements through intense to be of a much higher value than an Ruby on the calendar Included crystals of zircon, and related heating is sometimes used to equally fine ruby from a different locality. stress fractures (or halos) are sometimes strengthen the colour of some rubies. Colour is of extreme importance. The Ruby is a birthstone for the month of July. seen. Liquid-filled “fingerprint” inclusions more purely red a ruby is, without undue 15th and 40th anniversaries are celebrated c. Oil and dye – Some rubies with surface are also common. influences of purple or brown, the more with ruby. reaching fissures may be treated with collectible it becomes. Note some of these identifying oil or dyes, resulting in stronger colours. What a ruby is characteristics may disappear, change or The treatments are not considered Clarity and size of the gem is also be diminished as a result of treatments. durable and require special care important, though the presence of silk A variety of the mineral species corundum, considerations. or other inclusions is often valued since forming in the hexagonal crystal system it not only points to a gem’s natural with the chemical composition of Al O . d. Glass filling in cavities and fissures 2 3 origin; it also suggests the gem has – High lead content glass is sometimes Colours: orange red to strongly purplish not been treated. Cut or carved rubies used to fill surface reaching fissures, red; also brownish red. The dominant that have known provenance are also pits or cracks in certain rubies/ colour must be red. collectible. corundum. The treatment increases Refractive Index: 1.762 to 1.770 the transparency of low-grade ruby/ (+0.009, -0.005) corundum.

51 CIBJO Retailers’ Reference Guide May 2010 Gemstones Ruby

Star rubies are rare and collectible The cutting and care of rubies especially if the legs of the star reach Rubies are mostly cut in traditional from girdle to girdle of the cabochon, pear, round, oval, cushion and emerald and are unwavering and sharp. Star cut outlines. They are rarely engraved rubies often have a milky complexion or carved today, though rubies were due to inclusions of rutile, so depth of sometimes engraved during India’s colour and transparency are additional Mughal Era. Rubies are extremely important factors in valuing and durable due to their hardness and collecting star rubies. toughness – second after diamond on the Mohs Hardness Scale. Ruby jewellery A ruby’s dominant colour must Star rubies are appreciated Ruby localities may be cleaned in an ultrasonic cleaner, be red, such as in this gem from for their colour as well as the Thailand, Burma (Myanmar), Cambodia, or it may be steamed. But this should Mogok, Burma. sharpness of the star effect. Sri Lanka, Kenya, Afghanistan, India, follow close inspection to determine Pakistan, Tanzania, Greenland, Tajikistan if there are any surface reaching are all sources for rubies. fissures that could expand, or if oils or dyes are present. As with most Rutile needles in ruby are often gemstones, a soft moistened cloth, fine enough to be labeled as or a soft bristle toothbrush may be “silk.” The needles are oriented used to clean the gem. in directions of the ruby’s hexagonal growth structure, and may cause asterism.

52 CIBJO Retailers’ Reference Guide May 2010 Gemstones Sapphire

Appreciation for sapphire And grief and vain suspicions drive away. best qualities have a flower comparison, as The blue sort feels heaven’s changes they did in ancient times: today their colour If blue is the colour you think of when as they play, is compared with cornflowers. the word “sapphire” is said, you are very Bright on the sunny, dull when dark the day, close to its root. It derives from Hebrew The allusion to flowers does not end there. But best that gem which not too deep a hue, and Arabic terms safir, meaning blue, and Colour variations are what make this O’erloads, nor yet degrades too light sappheiros, meaning blue in Greek. In variety of corundum so interesting, as are a blue. ancient times, such words referred to a blue the “mixed colours.” One important gem gemstone, most likely what we know as Even then, a classification of “hyacinth’s with a blend of colours, which captivates lapis lazuli today. Conversely, the ancients beauty was tacitly underway. The reference the imagination, is the padparadscha called the today’s sapphire “hyacinth,” due to blue hyacinths, lovely flowers, remains sapphire. Padparadscha (which derives from to its colour similarity to blue hyacinths. an apt association. But the term began to Sinhalese language meaning lotus blossom) Obviously that term has changed with the fade. In the 15th Century, the naturalist is an extraordinary and rare variety. This passage of time, though a lovely poem Camillo Leonardo spoke and wrote about gem blends intense light to medium pinkish about gems by Marbodus, the Bishop of “sapphirini.” orange to orange-pink colours, in order to Rennes writtenapproximately 1000 years be thought of as padparadscha. Modern day usage of sapphire includes ago speaks of the colours of hyacinth, as almost all colours of the spectrum other In recent years, there has been a growing follows: than just blue – as Marbod’s poem appreciation for phenomenal gems – of Three various kinds the skilled as suggests. Sapphires, in fact, can be which sapphire enjoys two principal Hyacinths name, any colour but red. That’s because red varieties: Star sapphires in blue and various Varying in colour, and unlike in fame: corundum (though essentially the same other colours, cut as cabochons, and One, like pomegranate flowers mineral as sapphire) is classified as a ruby. colour-change sapphires have both received a fiery blaze In short, the difference between ruby and increasing attention in recent years. And one, the yellow citron’s hue displays sapphire is that only ruby can be red! So in One charms with paley blue the gazer’s eye, separate colours of sapphire, descriptions Sapphire on the calendar Like the mild tint that decks the are preceded by a colour designation, such Sapphire is the birthstone for the month northern sky, as “yellow sapphire.” Corundum, other of September. It is used to celebrate A strengthening power the several than red or blue, may also be referred to 5th and 45th anniversaries. kinds convey, as “fancy sapphire.” Blue sapphires in their

53 CIBJO Retailers’ Reference Guide May 2010 Gemstones Sapphire

What a Sapphire is Pink: chromium; possibly titanium. Colour dark blue or green sapphires to be For more information about CIBJO standards change: combined presence of chromium, lightened in tone, or to turn purplish A variety of the mineral species and rules regarding treatments, artificial and vanadium, iron and titanium. sapphires into pink colours. corundum, forming in the hexagonal imitation products, or synthetic stones please crystal system with the chemical Hardness: 9 on the Mohs Hardness Scale. b. Diffusion – Heating certain sapphires download a free pdf copy of the CIBJO composition of Al O . to very high temperatures allows a Coloured Gemstone Bluebook: www.cibjo.org 2 3 Internal identifying characteristics: secondary treatment, called diffusion, Colours: Blue sapphire: very light to very Inclusions in sapphire may be composed to take place. Elements, such as dark violetish blue to greenish blue. Fancy of fine rutile needles (called silk), which beryllium or titanium, are diffused into Collector sapphires colours: All colours of the corundum may intersect at 60-degree angles. In such the corundum, causing colours in the species excepting blue and red (blue cases, when the gem is cut as a cabochon, Several factors may be used to judge gem being treated to deepen or change. sapphire and ruby respectively). These star effect may occur. Included zircon fineness in sapphire, though ultimately colours include green, yellow, orange, pink, crystals or crystals of different minerals c. Coating – On rare occasions, some beauty of a gemstone remains in the eye purple, violet, brown, black, and colourless. may occur in sapphires and colour zoning, sapphires are coated with thin films of the beholder. Blue sapphires – collector Sapphires may also contain two colours, particularly seen in angular patterns. These that cause the colour of the sapphire gems – should possess the ability to be mixed colours or other variations. In recent are sometimes fingerprint inclusions. to deepen or change. spotted from across the room because years pale coloured sapphires of various of their depth and saturation. The d. Irradiation – In some cases, colourless colours have come to be known as “pastel Sapphire’s treatments transparency of the sapphires also comes to near colourless sapphire can be sapphires” in the trade. into play. Because inclusions can cause a. Heating – This treatment is designed turned orange or yellow though some gems to have milky colouration, Refractive Index: 1.762 to 1.770 to increase transparency by reducing irradiation. Colour in irradiated this becomes a detriment if it also causes (+0.009, -0.005). the opacity of clouds of rutile sapphires fades over time. a perceived loss of blue. In one notable inclusions. While the treatment helps Birefringence: 0.008 to 0.010 d. Glass filling in cavities and fissures exception, haziness is not only expected; to improve the clarity of slightly – While this treatment is less prevalent it is desired – and that is in the top Specific Gravity: 4.00 (+0.10, -0.05) included gems, it has also been in sapphires than in rubies, it should sapphires from Kashmir. The haziness performed on low quality sapphire Cause(s) of colour: Blue: iron and titanium. be noted that any gem material with (often referred to as sleepiness) acts material known as geuda. This is a high Green: iron or iron and titanium. Yellow: surface reaching fissures might be to diffuse light and colour, resulting in temperature treatment that results iron; orange: iron (and possibly chromium subjected to infilling of glass or other magnificently even blue colouration. in strong blue and yellow colours. in padparadscha variety). Purple: varying substances, with the goal of increasing Heating may also cause some overly traces of iron, titanium and chromium. the transparency of the gem.

54 CIBJO Retailers’ Reference Guide May 2010 Gemstones Sapphire

In recent years, Gemstones coming mixes of pink and orange colours as well. Blue is the colour most often from various localities around the world, Australia, Thailand, Cambodia, Kenya, associated with sapphire, such as such as the island of Madagascar, or the India, Tanzania, Madagascar, United in this fine, deep blue sapphire Umba River Valley in East Africa, have States all produce extremely fine blue from Burma. supplied unique palettes of colours. Many sapphires, as well as many fancy coloured such sapphires are unique enough to ones. Fancy sapphires are also produced be considered for collections, especially in other countries such as Vietnam and in suites showing an array of hues. East Zimbabwe. Africa and Madagascar have joined other sources such as Sri Lanka in bringing to The cutting and care of sapphires market rare colour change sapphires, Fancy coloured sapphires are colours Sapphires are mostly cut in traditional many changing from a blue grey colour other than blue, such as the majority pear, round, oval, cushion and emerald cut in daylight, to a violet or purple colour of sapphires shown here. Lighter outlines. They are sometimes engraved in incandescent light. Star sapphires coloured sapphires are also known or carved today, though sapphires were with strong colour in which the “legs” as “pastel” in the trade. sometimes engraved during India’s Mughal of the star are girdle to girdle, straight Era. Sapphires are extremely durable due to and unwavering. Fine padparadschas their hardness and exceptional toughness; are also considered collectible. they are second after diamond on the Mohs Hardness Scale. Sapphire jewellery may be Sapphire localities cleaned in an ultrasonic cleaner, or it may Sapphires may contain fine Sri Lanka and Burma are historic sources be steamed. But this should follow close needles inclusions of another for sapphire and produce some of the inspection to determine if there is any mineral, such as rutile. These world’s finest gems. In extremely high surfacereaching fissure that could expand, intersect at 60 degree angles qualities, Kashmir has emerged as the causing damage. As with most gemstones, and may cause asterism in some preeminent source for blue sapphires as a soft moistened cloth, or a soft bristle sapphires. the standard for fineness. Sri Lanka is the toothbrush may be used to clean the gem. classic source for padparadscha sapphires, though other sources also now produce

55 CIBJO Retailers’ Reference Guide May 2010 Gemstones Spinel

Appreciation for spinel case, it is not a detriment. Spinels stand This combination of optical characteristics on their own as magnificent gems, capable render spinels bright and reflective, and Spinel has long been one of the most at the very least of equal beauty as their capable of breaking up white light into underestimated gems on earth, but that corundum counterparts. Appreciation for spectral hues – what we call “fire.” It may factor is rapidly changing. With education, spinels inevitably brings us to one of the be this fire that first gave spinel its name: a greater understanding of the gemstone’s world’s greatest collectors of gemstones. one derivation of the word comes from the unique optical characteristics, its rarity, Among the Iranian crown jewels is one Greek spinter – meaning spark. and versatility is taking place. Because named the Samarian Spinel. Weighing spinel is one of the only species of in at 500 carats, it is thought to be the Spinel on the calendar gemstones in the world that is not treated world’s largest spinel. Its provenance commercially to enhance or change its Spinel is not a birthstone on the modern dates back to the 18th Century Persian characteristics, some gemological purists calendar but is used to commemorate conquest of India. An inscription on the and collectors are also devoted to it. a 22nd anniversary. back of the spinel confirms that the great Spinel has been known since ancient Indian Mughal gem collector, Jehangir, had What a Spinel is times, though it is likely the gem was once owned it. Interestingly, the Timur often confused with corundum; blue and Spinel in the British crown jewels bears Spinel is a mineral species whose varieties red spinel can look very similar to blue an inscription indicating Jehangir had also are primarily distinguished by their colour. sapphire and ruby, respectively. For years owned it. Much of the appreciation for It forms in the cubic crystal system, and its

it was referred to as “balas ruby” because spinel is due to its unique gemology. There basic chemical composition is: MgAl2O4. a source for the material in present-day is a clarity and directness about spinel that Colours: red, pink, orange, blue, violet, purple Badakshan in northeastern Afghanistan. In many enthusiasts appreciate. Optically, are the most common colours. Other colours the chapter on ruby, it was noted that the spinels are singly refractive, meaning that include brown and black, and rarely, yellow, Black Prince’s Ruby, the centrepiece of the light passing through them is not split into green and near colourless. Colour change British Imperial State Crown… is actually a two rays, as it does with birefringent gems, spinels change from greyish blue in daylight spinel. Another gem set in the crown is the such as corundum. Spinels have a high to purple in incandescent light. Timur Ruby, a 361-carat gemstone that is refractive index, and many transparent also a spinel. It is thought that many other spinels are relatively inclusion-free. Finally, Refractive Index: 1.718 (+0.017, -0.008) gems decorating the crowns of Europe spinels have high dispersion. Birefringence: None may in fact be spinel. Should that be the

56 CIBJO Retailers’ Reference Guide May 2010 Gemstones Spinel

Specific Gravity: 3.60 (+0.10, -0.03) Collector spinel The cutting and care of spinels Cause(s) of colour: Blue: iron, cobalt. Colour, carat weight, clarity and origin all Spinels are resilient and tough – more Red to pink: chromium. play a role in how spinels are valued and so than many gems (except corundum collected. Gems whose provenance can or diamond.) They may be cleaned in an Hardness: 8 on the Mohs Hardness Scale. be ascertained always have collectors. ultrasonic cleaner or steam cleaned. It Internal identifying characteristics: Red spinels that are deep red, large and is preferable to simply use a damp soft Minute fingerprint inclusions may be seen relatively free of inclusions are also cloth or a soft bristle toothbrush to clean in spinels. With sufficient magnification, highly desired. So too are rare, deep blue the gemstones and spinel jewellery. tiny octahedral crystals may be seen. spinels, particularly when a gemological These octahedral crystals, if large enough, laboratory has determined that cobalt is may be accompanied by strain halos. the colouring agent. Locality is playing an important role for collectors as well. Spinel’s treatments Rare spinels from the Pamir Mountains are collectible, as are spinels from Spinels are rarely treated, though Burma. New localities that produce Spinels occur in a wide variety of colours and occasional experimental heating of desirable colour – anywhere from pink have been confused with a variety of gems in spinel has been reported. Spinels with to deep red are collectible. the corundum species. surface reaching fissures are infrequently treated with oils or polymers. Spinel localities Afghanistan – especially in the region of Badakshan, in the Pamir Mountains, For more information about CIBJO standards remains a classic source for the gem. and rules regarding treatments, artificial and Burma is also a classic source and remains imitation products, or synthetic stones please a strong producer of the material. Sri Spinels may contain tiny octahedral download a free pdf copy of the CIBJO Lanka, Cambodia, Thailand, Kenya, crystal inclusions, such as the Coloured Gemstone Bluebook: www.cibjo.org Tanzania, Russia have all produced spinel. ones shown here, viewed through Recent spinel finds in East Africa have a microscope. These are proof of reinvigorated interest in the gem. the gemstone’s natural origins.

57 CIBJO Retailers’ Reference Guide May 2010 Gemstones Tanzanite

Appreciation for tanzanite De Sousa made a startling discovery found that low grade heating turned the himself. Around noon, he discovered a blue gems into a deep purplish blue. While Tanzanite, a variety of the mineral zoisite, crystal lying on the ground. The crystal was some blue zoisite is considered to be that is a relatively new gemstone on the unknown to him, though after consulting colour naturally, it is understood that all market so it does not share the depth a few books, De Sousa soon discounted of the commercially mined zoisite today of history presented by other gems. Its sapphire and iolite as possibilities. He is heated to induce the deep, velvety, blue beauty, though, is no less appealing, and finally decided it was a form of olivine, to violet blue colours one associates with the history it does have is intriguing. In and on July 25 pegged a claim for it. Soon the gem. years to come, tanzanite’s find will clearly other claims were made near his – but be looked back upon as one of the most There is much to appreciate about the material was being called something significant new gem discoveries of the tanzanite: its deep blue to violet colours, else: zoisite. Zoisite is actually distantly 20th Century. are of course paramount. It can be found related to olivine. According to John Saul, in sizable crystals and suitable for centre Several stories relate the discovery of a geologist and gem miner from Tanzania, stones in jewellery. It is also trichroic, tanzanite. The one most often told is confirmations of the mineral zoisite soon meaning that light entering the gem is that of Manuel De Souza, an Indian tailor came from the Gemological Institute of split into three different wavelengths. As from Goa living in Arusha, Tanzania. On America and from other experts around a result, tilting the gem in three different July 7, 1967 De Souza (who doubled as the world. directions one is sometimes able to see a gold and gemstone prospector) found Henry Platt, vice president of Tiffany & three different colours of zoisite. Viewed himself in the hilly region of Merelani in Co., who had been shown the material, in a polariscope, these colours become the company of four Masai tribesmen and who had admired it, was the first to even more evident. he had hired to help him prospect. The call it “tanzanite,” in honor of the country region, at the foothills of majestic Mount where it was found; the name was soon Tanzanite on the calendar Kilimanjaro, was dangerous: poisonous duly inscribed in new gemological texts. snakes, Cape buffalo, lions and other Tanzanite was recently added as an Indeed, tanzanite is not mined elsewhere African animals roamed the area. Accounts alternate birthstone for the month on a commercial basis. While almost all say De Sousa was unarmed but for a of December. of the material coming out of the mines few prospecting tools, seeking only what at Merelani was (and is) a somewhat drab providence might offer. But rather than purplish to yellowish brown, it was soon being discovered by man-eating beasts,

58 CIBJO Retailers’ Reference Guide May 2010 Gemstones Tanzanite

What a tanzanite is Tanzanite’s treatments Tanzanite localities The cutting and care of tanzanites A variety of the mineral species zoisite, Heating causes a change of colour from Merelani, Tanzania. At the time of writing, Tanzanites are delicate and should be worn (in the epidote group), forming in the brown, purple or grey to bluish purple to Merelani is the only known locality for with great care. Tanzanites should never be orthorhombic crystal system, and purplish blue. tanzanite in the world. While zoisite does cleaned in an ultrasonic cleaner or steam containing the following elements: occur in other places, no material matches cleaned. Warm soapy water or a damp soft

Ca2Al3(SiO4)3(OH). the colour intensity of tanzanite. cloth is considered a safe way to clean For more information about CIBJO standards tanzanite jewellery. Colour(s): Transparent blue to violet to and rules regarding treatments, artificial and bluish purple. A few very rare variations imitation products, or synthetic stones please of colour exist in zoisite from Merelani. download a free pdf copy of the CIBJO These forms are sometimes referred to as Coloured Gemstone Bluebook: www.cibjo.org “fancy colour” tanzanite. Colours including pink, orange, yellow and green transparent zoisites have been reported. Collector tanzanites Refractive Index: 1.691 to 1.700 (+/- 0.005) Tanzanites in large sizes, and rich colour are desirable for collections. Some tanzanites Birefringence: 0.008 to 0.013 are carved or sculpted by famous lapidary Specific Gravity: 3.35 (+0.10, -0.25) artists and as such are considered collectible. Cause(s) of colour: Blue: vanadium Finally, multi colour transparent zoisites Hardness: 6 to 7 on the Mohs Hardness (fancy tanzanites) are also sought, Other colours of transparent zoisite Scale. particularly green and pink. On extremely include green and pink, which are very rare. Internal identifying characteristics: rare occasion, collectible cat’s eye The yellowish brown colour (centre), is Many tanzanites tend to be remarkably tanzanites are fashioned. generally treated with low heat to result in clean and transparent. Fingerprint inclusions Colours one associates with the blue colours associated with tanzanite. are sometimes present. Very rare, tiny, tanzanite are blue to violet to bluish While some tanzanites are mined with the parallel, hollow tubes in some tanzanites purple, such as in the selection of bluish purple colours, most on the market cause chatoyancy (cat’s eye effect). tanzanites shown here. have been heat-treated.

59 CIBJO Retailers’ Reference Guide May 2010 Gemstones Topaz

Appreciation for topaz the 11th Century that the name began to A more recent inventory of the crown clearly point to a yellow or golden colour. jewels uncovered a rounded pebble of There is an unmistakable characteristic Scholars suggest that this definition could aquamarine. It was of a similar weight and about the colour of imperial topaz: a deep have encompassed several other yellow description, leading some to believe this yellow verging on orange, tinged with gold. gems that weren’t necessarily the topaz we might have been the gem in question. While some enthusiasts considered this identify today. golden colour the classic colour, pink to While natural bluish topaz exists, it is reddish orange hues are equally desired. Yellow and golden colours are iconic for generally quite pale. But one of the most Pablo Neruda, the Chilean poet, likened today’s definition of topaz, as Neruda prolific treated gemstones on the market topaz to honey: clearly identifies in his poem. Actually the today is a deep blue coloured topaz that is species occurs in a broader range of colours, treated with a combination or irradiation I invite you to a topaz. as well as colourless. Topaz sometimes and heating to achieve a broad range of To the honeycomb of yellow stone, includes a soft blending of pinkish orange popular blue colours. To its bees, to reddish orange colours, which the gem To the frozen honey of a topaz, trade has called “imperial topaz.” These Topaz on the calendar To its golden day… colours have been found at various sources Topaz is a birthstone for the month of Origin of the word topaz is quite around the world. But curiously, the rich November. It is used as an anniversary mysterious as it was once reserved for green colour with which topaz was first gemstone for a 4th anniversary – when greenish gemstones – most likely peridots. identified, does not exist – except rarely in blue topaz is given; and a 23rd anniversary, Topazos is Greek in origin, and refers to the very pale stones. which is reserved for imperial topaz. gems from the island of “Topazios,” which Topaz, in its purest colourless state was is known today as Zabargad. However that sometimes mistaken for diamond in Red Sea island is identified as the classic ancient times. The so-called “Braganza source of peridot. Dating back to Pliny Diamond,” a rounded pebble centrepiece of the Elder’s time, topazos was described the Portuguese Crown Jewels in the 1700s, as a gem the colour of fresh green olive was said to be the largest diamond in the oil. Slowly, over time, other colours were world at 1680 carats. Identity of the gem included within the definition of topazos, remains in dispute; it was thought at one including yellowish gems. It was not until time to have actually been a topaz.

60 CIBJO Retailers’ Reference Guide May 2010 Gemstones Topaz

What a topaz is Internal identifying characteristics: Collector topazes Topaz localities Liquid inclusions that contain two and A mineral species in the orthorhombic Colour is the principal feature of topaz Brazil – particularly the area near the three phase inclusions are the most crystal system. Its chemical composition with pink to orange to reddish orange town of Ouro Preto in Minas Gerais, common, particularly in reddish or orange is Al (F,OH) SiO . combinations being among the most produces much of the world’s supply of 2 2 4 gems. Occasionally trapped minerals such collectible. Size of the gemstone is classic yellow to orangy pink colours. Colour(s): Colourless, yellow, orange, as rutile can be found in topaz. In very rare also an important attribute, even in Other states produce it as well, but brown, pink to red to purple red. cases, tiny ribbon like hollow tubes, forming irradiated material where huge museum- mostly in the colourless to pale blue Light blue to dark blue and light green. in parallel fashion, cause cat’s eye effect. quality gems are occasionally available. range. Schneckenstein, a village in Refractive Index: 1.619 to 1.627 Germany, was a major classic source of Topaz treatments Topaz has perfect cleavage in one (+/-0.010) European topaz in the 1700s. Pakistan direction, so carvings are rare. When a. Heating – In some cases, yellow or produces some of the strongest pink Birefringence: 0.008 to 0.010 they do occur, especially by known brown topaz may be changed to pink to reddish colours at Katlang, near artists, they are soon collected. Specific Gravity:3.53 (+/- 0.04) or red colours. Peshawar. Topaz is also found at sources all around the world, such as Nigeria, Cause(s) of colour: Pink and red topazes b. Irradiation / followed by heating – Australia, Burma, Mexico, Namibia, Sri are principally coloured by chromium. Blue, This treatment begins with induced Lanka, United States and Russia. yellow and brown owe their perceived irradiation causing colourless topaz to colour to various colour centres, and possibly turn brown or brownish green. A heat combined with traces of chromium in treatment follows, turning the material orange hues. blue. In rare cases, some material may retain residual radioactivity. Hardness: 8 on the Mohs Hardness Scale.

For more information about CIBJO standards and rules regarding treatments, artificial and imitation products, or synthetic stones please download a free pdf copy of the CIBJO Coloured Gemstone Bluebook: www.cibjo.org

61 CIBJO Retailers’ Reference Guide May 2010 Gemstones Topaz

The cutting and care of topaz Prevalent on the market are a wide While topaz is quite hard, its toughness range of deep blue coloured topaz, such and resistance to blows is considered as those shown here. These stones owe poor because of its perfect directional their colour to a combination cleavage. Treated gems may be even more of irradiation and heating treatments, vulnerable to cleaving. Ultrasonic cleaners which turn essentially colourless topaz and steamers should be avoided. A soft, into a varieties of pale to deep blue damp cloth remains the best way to clean colours. topaz and topaz jewellery.

Sought-after varieties of topaz, especially Topaz varieties contain fluid among collectors, are in the pink to pinkish inclusions such as this one. orange to reddish orange colour range. These inclusions as best viewed under 10 to 60x magnification in a microscope.

62 CIBJO Retailers’ Reference Guide May 2010 Gemstones Tourmaline

Appreciation for tourmaline characteristics –which later were “Brazilian” in front of it. Obviously, in this scientifically determined as this gem’s case, Brazilian “emeralds” weren’t quite Tourmaline is a group of closely related unique piezoelectric and pyroelectric the same as the Colombian material. They gem materials composed of several properties. Those who smoked pipes, for were tourmalines! species and varieties of gemstones. The example, appreciated the gems’ apparent celebrated gemologist and author, Eduard In recent years, tourmaline has witnessed magnetic ability to draw ashes out of Gübelin, referred to it as a “crystallized a true renaissance, particularly after their pipes; as the gems were heated, they kaleidoscope” because of the diversity the discovery of a copper-rich elbaite developed positive and negative charges at of colours that make up this rich tourmaline from the State of Paraiba, the ends of the crystals. These tourmalines family. Tourmaline comprises colours Brazil. While the locality produced a were nicknamed aschentrecker, which of the spectrum from red to violet and modest quantity of material for a short translates to “ashpuller.” practically any degree of variations in time, its vivid colours, influenced by between. Tourmaline can also be bi- Curiously, tourmaline had already arrived the copper impurities, were considered coloured or black. Enthusiasts know that on European shores at the time of Pliny so unique that they revolutionized the tourmaline’s variety names are often the Elder. In his famous series of books tourmaline business. Demand for all designated by these hues. However, most on natural history, Pliny described similar tourmalines enjoyed an increase since of the gem tourmalines used in jewellery electrical properties in a gemstone he the late 1980s, when the cuprian elbaites today are members of the elbaite mineral named lychnis. Because he also noted were first discovered. Since then, copper species, which exhibits the strongest and that colours were reddish or violet rich elbaites have been found at two other brightest colours. The coloured varieties in colour, it is believed the gem was localities around the world. of elbaite, and their respective names, probably tourmaline – the gem we know are listed below. and enjoy today. Tourmaline on the calendar The name tourmaline derives from Confusion was sown in the 1500s Tourmaline is a birthstone for the month the Sinhalese word turamali, meaning when Portuguese explorers looking for of October. gemstone with mixed colours. In the emeralds in Brazil chanced upon rich, early 1700s, traders from Holland green, emerald-looking gemstones. Swiss brought turamali back to Europe from naturalist, Conrad Gessner, saw this Ceylon (Sri Lanka). They were fascinated material in Europe. Though he classified with the material’s apparent electrical it as “emerald,” he also included the word

63 CIBJO Retailers’ Reference Guide May 2010 Gemstones Tourmaline

What a tourmaline is Watermelon – Pink centres with green Internal identifying characteristics: around the outer margins of the stone. Tourmalines have abundant liquid For more information about CIBJO standards A group of mineral species that inclusions, which look like thin, and rules regarding treatments, artificial and includes the following: dravite, uvite, Chrome tourmaline – A deep, solidly green, threadlike and elongated fingerprints. imitation products, or synthetic stones please olenite, schorl, elbaite, liddicoatite and chromium-containing gem. Some tourmalines also contain download a free pdf copy of the CIBJO buergerite. Gem varieties are contained Cat’s eye tourmaline – Tiny hollow growth elongated hollow tubes that form in Coloured Gemstone Bluebook: www.cibjo.org in elbaite and liddicoatite species. Both tubes in some cabochon-cut tourmalines parallel fashion during growth, and form in the hexagonal crystal system, cause a cat’s eye effect in direct lighting. these exhibit cat’s eye phenomena. mostly as trigonal, prismatic crystals. Collector tourmalines Elbaite contains the following chemical Liddicoatite – This species of tourmaline is Tourmaline’s treatments compositions: (Ca, K, Na) (Al, Fe, Li, Mg, calcium-rich, lithium tourmaline that was The word “paraiba” – which rapidly became a widespread descriptor for Mn)3 (Al, Cr, Fe, V)6 (BO3) 3Si6O18 (OH, F)4. named its own species in 1977 – in honor a. Heating – This treatment aims to of one of GIA’s founding fathers, the noted produce lighter green gems and cuprian tourmalines from Brazil’s Paraiba Principal colour varieties: gemologist, Richard T. Liddicoat. This is a blue green colours from overly dark State, are highly sought after by many Rubellite – Pink to red range, may also parti-colour tourmaline par excellence – gems. In cuprian elbaites, heating collectors. be brownish, orangy, or purplish. a gem often exhibiting many colours in causes some dark purple material Copper bearing gems from Mozambique strongly zoned, geometric colour patterns. to become strongly greenish blue or Verdelite – Yellow green to bluish green. and Nigeria have also become quite deep blue. There are some undesirable Refractive Index: 1.624 to 1.644 popular, particularly as production Indicolite – Violetish to greenish blue. effects of heating: some pink and (+0.011, -0.009) quantities at the original source has red tourmaline may fade to nearly Dravite – Yellow to brown tourmalines. lagged. Birefringence: 0.018 to 0.040 colourless upon heating. One bright yellow variety has been called Rubellites with strong colour – especially “canary tourmaline” in the trade. Specific Gravity: 3.06 (+0.20, -0.06) b. Irradiation – This treatment was from sources that produced high qualities used to produce darker red gems Achroite – Colourless. Cause(s) of colour: Blue: iron. Red and for short times, such as Nigeria, are from light pinks. pink: manganese and some titanium. collectible. Indicolites that exhibit strong Parti-colour – Two or more colours. Green: iron, chromium and vanadium. blues are also very popular. (Note: if only two colours are seen, these gems are called bi-coloured.) Hardness: 7 to 7.5 on the Mohs Hardness Scale.

64 CIBJO Retailers’ Reference Guide May 2010 Gemstones Tourmaline

Bi-colour tourmalines showing strong The cutting and care Tourmaline is assuredly the world’s most colour zoning, parti-colour gems and of tourmalines colourful gemstone family, containing all cat’s eye tourmalines are also collected. colours of the visible spectrum. Tourmalines Tourmalines’ elongated, prismatic crystals In rare instances when “chrome” green with two or more colours within a single dictate how the gemstones are cut, tourmalines are found, they are collectible, gem are also popular. often resulting in very long, rectangular especially in larger sizes because of their shapes. While tourmalines can be cut in brilliant green colour. all shapes and sizes, rectangular shapes predominate. Crystals often exhibit more Tourmaline localities than one colour; in such cases bi-colour Brazil remains the world’s largest or parti-colour gemstones result. On rare Among the most popular varieties of producer of tourmaline in all colours. The occasions, tourmalines are also carved. tourmaline are indicoite (left), rubellite State of Paraiba produces Brazil’s most While tourmalines have adequate (centre) and verdelite (right). coveted cuprian tourmaline. Afghanistan hardness, there may be zones of weakness is known for a very bright blue green in some gems, particularly those that quality of tourmaline, though it also have many inclusions. Some bi-colour Copper-containing elbaite tourmalines from produces some green and pink varieties. tourmalines are weaker along the colour the State of Paraiba, Brazil have produced Burma, India, Kenya, Mozambique, boundaries. unique colours, including vivid greenish blue, Pakistan, Nigeria, Sri Lanka, Russia, deep blue, and bright, saturated greens such Tanzania all produce significant quantities Tourmalines should not be steam cleaned as the gems shown here. Collectors often of material in various colours. United or placed in an ultrasonic cleaner for these compete to own such gems. States – particularly the Pala district in reasons. Instead they should be cleaned California, is known for producing rich with a soft damp cloth or a soft bristle pink and rubellite varieties. Madagascar toothbrush. primarily produces rubellites and Tiny, hollow growth tubes in liddicoatite tourmalines. tourmaline may cause a cat’s eye effect in cabochon-cut gems.

65 CIBJO Retailers’ Reference Guide May 2010 Gemstones Turquoise

Appreciation for turquoise In the West, ancient Aztecs and Mayas Turquoise on the calendar traded turquoise from sources now known Turquoise’s startling blue colours and soft, Turquoise is the birthstone for December. as Southwestern U.S., and Mexico, and slightly porous texture may be the reasons It is also used to celebrate an 11th throughout the Americas. Further south, why it has been such an important opaque anniversary. in Peru, the pre-Colombian Chimú culture gem for thousands of years and across traded turquoise beads throughout the so many civilisations. Excavations from What a turquoise is Southern hemisphere. Pharaoh mummies dating five millennia Turquoise is a hydrous copper phosphate before the birth of Jesus contain evidence Given its colour, it comes as no surprise mineral in the triclinic crystal system. (turquoise bracelets) that the gem was that many civilizations felt turquoise Its chemical composition is CuAl (PO ) highly prized in ancient Egypt – both as a embodied elements of both the sky and 6 4 4 (OH) . H O. gemstone and as an ornamental material. sea. However that colour comparison 8 5 2 Successive Egyptian dynasties since then needs amplification: the colour of highly Colour(s): Light to medium blue, greenish used also the gem as a symbol of good desired turquoise is described as the blue blue to green, often mottled and may fortune. China was a source for turquoise of a robins egg, pale blue to blue-green show dark splotches of veins of matrix. during the time of Marco Polo’s travels, to dark blue. Further subtle variations Refractive Index: 1.610 to 1.650 and he found that turquoise beads were of colours exist. Deposits in China, for traded and bartered all along the Silk example, are known to produce a light to Birefringence: not detectable. Route. Along the same trading routes, dark green turquoise with little or no blue Specific Gravity: 2.76 (+0.14, -0.36) magnificent Persian turquoise made its component. way to both the East and West! Asians Cause(s) of colour: Copper for the bluish The name, “turquoise,” comes from the used turquoise beads for adornment, but colours, whereas greens are caused by 16th century French expression, pierre also as a form of currency and protection, a combination of copper and iron. de turquie, which translates to stone until the 1800s. from Turkey. While turquoise did not Hardness: 5 to 6 on the Mohs Hardness occur there, French merchants trading at Scale. Turkish bazaars likely believed that Persian Internal identifying characteristics: turquoise traded there was from Turkey. Because turquoise is always opaque, internal characteristics are not noticeable.

66 CIBJO Retailers’ Reference Guide May 2010 Gemstones Turquoise

However, turquoise may contain areas 3. Dyeing – This treatment also works Collectors of Native American turquoise of deeper colour or variations of colour because of turquoise’s porosity. The For more information about CIBJO standards jewellery prize material from assorted in the same gem. Matrix, a dark veining dyeing is sometimes used to deepen and rules regarding treatments, artificial and top artists who use material from several pattern that permeates some types of the colour of turquoise, or to simulate imitation products, or synthetic stones please mines across the Southwest. Large turquoise, is natural evidence of the matrix. download a free pdf copy of the CIBJO carvings of superb turquoise, especially element or substance in which turquoise Coloured Gemstone Bluebook: www.cibjo.org when these have been fashioned by known 4. Filling – Porosity and small cavities was formed. Because matrix is softer than artists, are also highly collectible. in natural turquoise can be filled with turquoise, it tends to weather (or erode) a polymer to create a homogenous more quickly. As a result, the darker Collector turquoises Turquoise localities surface. This form of treatment is often matrix areas are often deeper than the aided by vacuum pressure. Natural, untreated turquoise with a bright United States – mainly Arizona, New surrounding turquoise. Likewise, if natural luster and deep, blue homogenous colour Mexico, California and Nevada and Mexico turquoise is polished, matrix tends to 5. Surface coating – Some lacquers or – and no matrix veining is also highly are sources for material that has been be undercut. This means that the darker polymers may be used to coat the collectible. The same holds true with traded through the Americas for centuries. areas are generally deeper – not flush surface of the gem, deepening the turquoise that has known provenance. Most of the world’s supply of turquoise with the surface that is being polished. colour. “Spiderweb” matrix, containing fine dark comes from the United States and China Reconstitution of turquoise, while not today. Iran remains the classic source for Turquoise’s treatments lines with an attractive, even pattern a treatment in the traditional sense surrounded by deep blue turquoise is fine turquoise, though little material is 1. Plastic impregnation – This treatment (and thus not listed above) dramatically preferred by some collectors. While presently mined there. Australia and Chile introduces a polymer into the porous changes the appearance of low quality turquoise from Persia (Iran) was a long a are also sources for turquoise. areas of turquoise. The result is a darker, turquoise fragments. Here, smaller sizes standard for the finest turquoise, material more durable material. of turquoise are combined and ground from the United States – specifically into a powder. Following this, the powder 2. Wax impregnation – Again, this Arizona has proven to be of equal or is bonded together in a solid mass using works because of the porous nature greater quality in some cases. polymer resins. Its use in jewellery is of turquoise; a waxy substance lends widespread. the turquoise a more homogenous appearance. It does not make the gem more durable. The treatment is sensitive to even low heat.

67 CIBJO Retailers’ Reference Guide May 2010 Gemstones Turquoise

The cutting and care Natural turquoise may (or not) contain of turquoises matrix, as these natural samples show. Notice also the uneven colouration Turquoise can be fashioned into any of the beads; greener beads likely have shape, including carvings, though a slightly higher iron content. in most cases the material is cut in cabochon form. They are often fashioned as free-form beads (mostly with matrix) or perfectly homogenous, round beads with little or no matrix. Because of turquoise’s soft and porous nature, ultrasonic cleaners and steam cleaners should never be used to clean turquoise jewellery. The gem should be cleaned with a soft, dampened cloth. Turquoise beads may darken over time if they are in direct contact with skin.

Large chunks of turquoise are ideally suited for carving. It is rare for turquoise A highly desirable colour of turquoise is to be blemish free. In this case, often described as a “robin’s egg” blue, such turquoise material was ground as in the sample on the left. In recent years, and powdered, and then reconstituted a bluish green variety of turquoise from China using a polymer-resin binding agent. (on the right), has begun to enter the market The larger block was then carved. in large quantities.

68 CIBJO Retailers’ Reference Guide May 2010 Gemstones Zircon

Appreciation for zircon The word zircon derives from the Arabic Refractive Index: The RI varies, as follows: zar gun, meaning gold coloured, though, Zircon is winning over fans because of High: 1.925 to 1.984 (+/-0 .040) as noted, zircon is found in many colours. its unique colours and brilliant optical A range of red to orange, yellow to brown, Medium: 1.875 to 1.905 (+/- 0.030) characteristics. The first thing to know and blue to green are found – though about zircon is that it has nothing to Low: 1.810 to 1.815 (+/- 0.030) On rare natural blue zircon is quite rare. do with cubic zirconia (the trade name occasions the RI reading is below 1.80 for a man-made product that simulates Another optical characteristic of zircon Birefringence: 0.000 to 0.059 (low type diamond). Zircon is a natural gem that (except in metamict types) is its extreme has low birefringence, high type has higher might be confused with diamond in its double refraction, which is often easily birefringence). colourless varieties, but easily separated visible when looking through a gem’s upon closer examination. The appeal of table with the naked eye. The result is a Specific Gravity: 3.90 to 4.73 zircon’s many colour varieties lies in its perceived doubling of the pavilion facets (Increases from low to high type). extraordinary luster, brilliance and fire, and facet junctions – as well as its fire. Cause(s) of colour: Various colour centres. a product of high refractive indices and very high dispersion. Zircon on the calendar Hardness: 6 for low type; 7.5 for high type on the Mohs Hardness Scale. Three types of zircon have been identified: Zircon is a birthstone for the month of high, or alpha; low or gamma; or December, together with turquoise and Internal identifying characteristics: intermediate or beta. The classification tanzanite. In metamict zircons, angular colour ties into the gem’s crystal structure. zoning or angular markings can be seen, High or alpha zircons have normal crystal What a zircon is as well as an unusual milkiness in some structure – like most other crystalline gems. stones. In some metamict gems, discoid Zircon is a mineral species of the Low or gamma zircons are “metamict.” In fractures within the gem result in an tetragonal crystal system. Its chemical such cases the crystal structure is changed by unusual aventurescent effect. Apatite composition is ZrSiO . natural irradiation, and rendered amorphous. 4 and garnet crystals are sometimes found Partially crystalline gems, meanwhile, are in Colour(s): Colourless, blue, yellow, green, in zircon. the intermediate classification. The appeal brown, orange and red. Rarely: purple. of metamict zircons lies in their unique, often phenomenal effects.

69 CIBJO Retailers’ Reference Guide May 2010 Gemstones Zircon

Zircon’s treatments Zircon localities Heat treatment – Most brown zircon is Cambodia, Sri Lanka, Burma, Australia heat treated to result in different colours, and Thailand are the principal sources of including blue, red, orange or yellow. Green Zircon. Brown zircons from East Africa have zircons are occasionally heated to lighten also entered the market in recent years. Zircons occur naturally in a variety their tone. Induced changes in zircon’s of colours. Some zircons are subjected colour are not always stable and colours The cutting and care of zircons to additional treatments to result in may revert to their original colour upon Zircons, whose optical characteristics are different of deeper colours. exposure to light. sometimes compared to diamonds’ differ greatly in terms of hardness. Zircons are For more information about CIBJO standards quite soft and it is recommended that and rules regarding treatments, artificial and when worn in jewellery, the jewellery not imitation products, or synthetic stones please be subjected to rough wear (as in sports). download a free pdf copy of the CIBJO Facet junctions in zircons often abrade Coloured Gemstone Bluebook: www.cibjo.org over time with careless use. Warm soapy water or a damp cloth should be used to clean zircons. Ultrasonics or steam Collector zircons cleaners should not be used.

Some zircons are collected as colour At magnifications of between 10 - 60x, groups to exhibit an array of colours, and inclusions such as this iridescent, disc- large red zircons are particularly prized. like fissure may be seen in some zircons. Some collectors buy metamict gems that exhibit unique phenomenal characteristics such as aventurescence or cat’s eye. Cat’s eyes do occur in included material but the eye is generally indistinct.

70 CIBJO Retailers’ Reference Guide May 2010 Pearls Retailers’ Reference Guide PEARLS Contents: Pearls

3 Introduction – types of pearls The information in the following chapter was provided by the CIBJO Pearl Commission. Images provided for the Pearl chapter 5 Natural pearls by GIA, Shigeru Akamatsu, Japan Pearls Exporters Association and the SSEF. 8 Cultured pearls

9 Pearl culturing and the molluscs

11 Quality of the cultured pearl

14 Treatment of a pearl or cultured pearl

All rights reserved. No part of this Guide may be reproduced, republished, amended, translated or changed, including all images included in the Guide, without the express written permission of CIBJO or its authorised agents. Permission to republish, reproduce and/or translate of this Guide is limited to CIBJO member organisations only, and is subject to written agreements between CIBJO and/or its agents and the CIBJO membership organisation.

2 CIBJO Retailers’ Reference Guide May 2010 PEARLS Introduction – types of pearls

Types of pearls Whole-round natural pearls Pearls may be natural (nacreous or non- Pearls accidentally formed in a pearl sac nacreous) or cultured (nacreous only), they within molluscs without assistance from may come in a variety of colours, shapes man. A pearl-sac is derived from the and sizes and may be suitable to be strung internal or external layer of the epithelium in the form of necklaces, set in rings and of the mantle or of the gill plates. The brooches etc. Other important pearls have epithelial cells of the pearl-sac secretes had significant collector potential and the nacre (or non-nacreous material) have become the centrepiece of displays which becomes deposited over the foreign in museums and personal collections body, forming a pearl over time. Their throughout the world. entire surface is covered with nacre or Nacreous natural sea-water pearls of various An 850ct natural non-nacreous material. shapes and sizes being traded in Dubai (left) blister pearl Natural pearls and an important natural saltwater pearl Natural blister pearls Almost any mollusc can produce a natural necklace (right). pearl. Natural pearls form accidentally Pearls accidentally formed on the in the interior of molluscs without inner surface of mollusc’s shell without interference from man. Molluscs are an assistance from man. They first form as invertebrate with a soft unsegmented natural pearls in a pearl sac, then break body, usually protected by a shell in one, the sac to attach to the surface of the or two, pieces. Most molluscs live in, or shell, where the host mollusc covers their near, water. They occur in three basic surface with further layers of nacre or forms; whole-round pearls, blister pearls non-nacreous material. and blisters. Natural pearls may be nacreous or non- nacreous and come from either salt-water Cross-sections of freshwater natural or freshwater. pearls showing the typical concentric growth structures of natural pearls.

3 CIBJO Retailers’ Reference Guide May 2010 PEARLS Introduction – types of pearls

Natural blister Whole-round cultured pearl Cultured blister pearls Nacreous or non-nacreous substance Cultured pearls formed in a pearl sac Cultured pearls formed on the inner accidentally formed on the inner surface of a mollusc with the assistance of man. surface of mollusc shell with the of the mollusc shell without any assistance Human intervention only gives rise assistance of man. They form as whole- from man. They originate from the to the formation of the pearl sac and round cultured pearls in a pearl sac; they intrusion of a foreign material into a space the introduction of a shell-bead (in the then break from the pearl sac to attach between mantle and inner surface of the case of beaded cultured pearls). Whole to the surface of the shell, where the host A microradiograph (left) of a beaded cultured nacreous or non-nacreous shell, or the round cultured pearls are classified into mollusc covers their surface with nacre. pearl strung as part of a necklace shows the repair of a hole in the shell bored by the beaded cultured pearls and non-beaded bead inserted and the nacreous layers formed intrusion of a sponge, parasite. cultured pearls. Cultured blister during the growth period. A cross-section of (Hankei cultured pearls) a beaded cultured pearl (right) showing the Cultured pearls Beaded cultured pearl Pearls formed on the inner surface layered structure of the shell bead and the Cultured pearls are formed in molluscs Cultured pearls formed in a pearl sac of the shell of molluscs by attaching concentric nacreous overgrowth. with the assistance of man. However, this of the molluscs by inserting a piece hemispherical (including three-quarter) human intervention should only stimulate (or pieces) of epitherial tissue and a bead object (or objects). The entire surface of the mollusc to produce a pearl formation (or beads) made of shell. Bead (or beads) the object (or objects) is covered with (see later) and the substance formed are entirely covered with nacre secreted nacre secreted by molluscs. should only be that normally produced by by molluscs. the mollusc for form the shell or a natural Imitation pearls pearl. Cultured pearls occur in three Non-beaded cultured pearls Imitation pearls are artificial basic forms, the whole-round cultured Cultured pearls formed in a pearl sac in products not formed in molluscs but pearl (which may be either beaded or molluscs by inserting a piece (or pieces) manufactured by man to imitate the non-beaded), cultured blister pearls and of epitherial tissue. They are entirely appearance, colour and other features cultured blisters. composed of nacre secreted by molluscs. of natural or cultured pearls. Cross section of a non-beaded freshwater cultured pearl; showing that it has no bead at its centre and that it is composed entirely of nacre.

4 CIBJO Retailers’ Reference Guide May 2010 PEARLS Natural pearls

History Conch pearl Many historical documents show Conch pearls are produced by a that mankind has used natural pearls gastropod commonly known as the as ornaments since long before the “Queen” or “Giant conch” (Strombus beginning of the Christian era. In about gigas) that inhabits Caribbean waters. 4,000 BC, the Indian Ocean, the Red Sea Conch pearls differ from ordinary and the Gulf were famous for being a pearls by having a tough crossed rich source of natural pearls. In addition, lamellar micro-architecture that many European countries produced manifests itself as a flame-like structure freshwater natural pearls. that appears to move as “watered-silk” The pearling fleet returns home when the pearl is moved under light. In the New World, after the discovery after months at sea. Conch pearls are not cultured, they are of America by Columbus, numerous natural and come in a variety of colours. salt-water natural pearls were fished, However, some imitations are attempted especially in Mexico. From the 1930s by cutting the thick shell into beads. the nacreous natural pearl market contracted, largely due to the discovery Horse conch of oil in the Arabian Gulf and the appearance of cultured pearls. The Horse conch pearl is a natural pearl produced by Horse conch (Pleuroploca Natural pearls today gigantea), a very large gastropod inhabiting Indo-Pacific waters. It has Natural conch pearls of various colours. On the left a 111.59ct example of a natural Currently, most pearls sold are cultured, a orange to reddish brown colour, and pearl from Cassis Madagascarensis (the Queen but natural pearls are still available in possesses a unique surface pattern. Helmet); the remainder are all natural pearls specialist markets, particularly in the from Pleuroploca gigantea (the Horse Conch) Middle East and India. In addition, they and weigh 198.26ct (top left) 112.03ct (top can often be found in major auction sales. centre) 74.80ct (top right) and left to right in the bottom row 16.02ct, 11.16ct, 7.43ct, and 16.36ct.

5 CIBJO Retailers’ Reference Guide May 2010 PEARLS Natural pearls

Melo pearl A group of Melo pearls. Melo pearls are produced by the large volute with the genus Melo, inhabiting the South China Sea, the waters around the Philippines, the eastern coast of Indonesia and the Andaman Sea. In Taiwan, Malaysia, Indonesia China and Vietnam they are caught for food. Melo pearls are usually spherical and quite large but can also be baroque, The appearance of they have a yellowish brown to orange “watered-silk” on the and reddish brown colour. Like the surface of a Melo pearl. Conch pearl and Horse conch pearl, Melo pearls do not have a nacreous structure but instead a crossed lamellar micro-architecture. The species known to have produced natural pearls are Melo broderipii, Melo Amphora and Melo melo. The conceric growth structure of a sectioned Melo pearls may be produced by any Melo pearl. of the Melo volutes, illustated here is the shell of Melo melo.

6 CIBJO Retailers’ Reference Guide May 2010 PEARLS Natural pearls

Natural freshwater pearls Abalone pearl Most of the natural freshwater pearls on Abalone is a gastropod widely sale today are from the United States, inhabiting Pacific, Atlantic and Indian they are obtained as a by-product of Oceans. The population is particularly mussels collected as material for pearl rich along the coastal areas of Japan, culturing beads. Among pearls gathered, North America and Australia. Though those with interesting shapes such as abalone pearls are popular, round “Wing” and “Rose bud” and exceptional examples are very rare, as many colours are preferred. are horn-shaped. In addition, natural freshwater pearls are found in rivers throughout Europe, the UK and Ireland.

Fishing for natural An important single white natural A large horn-shaped natural abalone pearl freshwater pearls in freshwater pearl and necklace from along with a very rare near-round natural a fast flowing river the United States (top left) and a lilac abalone pearl (top right) and the interior in Scotland coloured natural freshwater pearl in of an abalone shell (bottom right). the mussel shell in which it was found (bottom left).

7 CIBJO Retailers’ Reference Guide May 2010 PEARLS Cultured pearls

History Pearl culturing methods The modern cultured pearl industry started At present three culturing techniques are Cultured blister (Hankei cultured pearl) with Mikimoto’s hemispherical cultured used to produce cultured pearls; beaded A hemispherical object (including three- pearl in 1893. In 1907 the technique of pearl culturing, non-beaded pearl culturing quarter) is placed on the inner surface spherical or whole pearl culturing was and hemispherical “Hankei” cultured pearl. of the shell and over time this is covered invented. Since then, the cultured pearl with nacre. The pearls produced by using Beaded cultured pearl industry has developed significantly. Pearl the Mabé oyster are the best known, as Based on Nishikawa’s “Piece method”, culturing areas have been extended, and a result Hankei cultured pearls are also a bead (or beads) and piece (or pieces) in addition to the Akoya oyster other called Mabé cultured pearls. of mantle tissue are inserted into an species such as Silver/Gold lipped oyster, oyster body. Most salt-water cultured Black lipped oyster, the abalone and (in pearls are beaded. freshwater) the Triangle mussel are used. Non-beaded Hankei cultured pearl A piece (or pieces) of mantle tissue is inserted into a pocket (or pockets) in the mantle of a mussel. Most of freshwater cultured pearls are non-beaded.

8 CIBJO Retailers’ Reference Guide May 2010 PEARLS Pearl culturing and the molluscs

Akoya pearl culturing Pearl culturing using the Akoya pearl oyster is carried out in Japan, China and Vietnam. Recently culturing has also started in Dubai. Compared with other pearl oysters the Akoya oyster is rather small, the size of the pearl is less than 10 mm. Most popular sizes are 6 and 7mm.

Silver/Gold-lipped pearl culturing The main culturing areas for the Silver and Gold-lipped pearl oysters are Australia and Indonesia, followed by the Akoya pearl culturing – inspecting the The bead insertion operation. Philippines. Though the oyster species is nets (left) and the Akoya shell (right). the same – Pinctada maxima – there are differences between pearl culturing in Australia, Indonesia and the Philippines. In Australia large sized and high quality pearls over 10mm are cultured using the Silver-lipped oyster, while in Indonesia many smaller sized cultured pearls of below 10mm are cultured. In the Philippines many golden pearls are cultured using Gold-lipped oyster.

The Silver-lipped (left) and the Gold-lipped (right) oyster shells.

9 CIBJO Retailers’ Reference Guide May 2010 PEARLS Pearl culturing and the molluscs

Black-lipped pearl culturing Inspecting the nets (left), French Polynesia is the main country for the black-lipped oyster shell (right) producing black cultured pearls using and the bead insertion operation (below). the Black-lipped pearl oyster. However, culturing areas are expanding to Fiji, New Caledonia, and the Cook Islands. Recently smaller-sized black cultured pearls of below 10mm are on the increase.

Freshwater pearl culturing Modern freshwater pearl culturing began in 1924 in Lake Biwa, Japan. Though pearl culturing was forced to stop because of World War II, the production volume increased thereafter. Production began to decrease from 1980, and today has reduced to almost zero. Chinese freshwater pearl culturing, started in 1981 with the export of 600g pearls to Japan. At present, annual Chinese freshwater cultured pearl production exceeds 1,500 tons. By the improvement of culturing techniques, large, round and smooth-surfaced pearls are able to be produced. However, large volumes of middle to low quality pearls are appearing on the world markets.

10 CIBJO Retailers’ Reference Guide May 2010 PEARLS Quality of the cultured pearl

Quality elements Nacre thickness Nacre thickness is closely related to the Size culturing period and may have some The popular size of cultured pearl impact on the colour, lustre and durability ranges from 2 - 13mm. The size range of the pearl. It is one of the most is dependent upon the oyster species important elements of pearl quality. X-rays used; Akoya cultured pearls range from are used to measure nacre thickness and 2 - 10mm, Silver/Gold-lipped and to assist in observing nacre quality. Black-lipped cultured pearls range from 8 - 13mm or larger, freshwater Surface cultured pearls range from 2 - 13mm. The surface of a cultured pearl is The size of cultured pearls is measured examined in terms of the number, size, in millimeters (mm). kind and location of the imperfection. In evaluating the imperfection, first, the Shape number of imperfections is taken into A perfectly round cultured pearl is worth account – whether a pearl has a clean the highest value. However, a beautiful surface, one spot or many spots. Then A microradiograph indicating the symmetrical drop shape is also highly the kind of imperfection is examined measurement of nacre thickness. valued. Shape is divided into the following: whether it is a dent or a bump on the round, semi-round, oval, drop, button, surface; imperfections are subdivided semi-baroque, baroque and circled. into pits, holes, pinpoints, bumps and wells. Even if the imperfection seems insignificant, if it is visible to the eye, it lowers the value of the pearl.

11 CIBJO Retailers’ Reference Guide May 2010 PEARLS Quality of the cultured pearl

Lustre Pearl lustre is defined by the quality of the reflected light. A lustrous pearl has a strong bright and sharp reflection. A low lustre pearl on the other hand is not bright and its reflection is dull. The lustre of a pearl may be closely related to the homogeneity, light transmittance and thickness of the nacre. Recently, as cultured pearl dealers prefer a high lustre, many pearls are heavily polished. Colour There are three main causes of pearl colour; light phenomena, especially interference of the light, pigments An illustration of variously contained in conchiolin and organic coloured cultured pearls. matter formed in the clearance between the inner surface of the nacre and outer surface of the bead. Colour characteristics differ according to a mother oyster species.

An illustration of high surface lustre in Akoya cultured pearls.

12 CIBJO Retailers’ Reference Guide May 2010 PEARLS Quality of the cultured pearl

Quality characteristics of Black-lipped cultured pearl cultured pearls as they relate Size: Over 10mm is the most popular. to the producing mollusc Recently smaller sizes (8, 9mm) have Akoya cultured pearl appeared. Size: 2 -10mm. 6 and 7mm are the Shape: Same as Akoya cultured pearl. most popular. Nacre thickness: Thick nacre Shape: Round, semi-round, oval, button, Colour: Black, green, brown, blue, drop, semi-baroque, baroque and circle. grey, peacock, red Nacre thickness: Minimum is around Freshwater cultured pearl 0.3mm. Size: 3 to over 10mm Colour: Pink, green pink, silver pink, cream pink, white, green, cream, gold. Shape: Round, semi-round, oval, rice, button, drop, baroque Silver/Gold-lipped cultured pearl Colour: Three basic colours (orange, Size: Over 10mm is the most popular. purple and white) Recently smaller sizes (8, 9mm) have appeared. Shape: Same as Akoya cultured pearl. Nacre thickness: Thick nacre Colour: Silver, silver pink, pink, grey, cream, golden and yellow. Akoya cultured pearls (top left), Silver- and Gold-lipped cultured pearls (top right), Black-lipped cultured pearls (bottom left) and freshwater cultured pearls (bottom right).

13 CIBJO Retailers’ Reference Guide May 2010 PEARLS Treatment of a pearl or cultured pearl

Treatment is any action by man (other Irradiation: exposing pearls or cultured Detail of a dyed pearl. than polishing, cleaning, buffing and pearls to radiation. peeling) that alters the appearance of Lustre enhancement: Any treatment a pearl or cultured pearl. The following or process applied to enhance the lustre treatments must be declared at the of a natural or cultured pearl point of sale. Oiling: a process sometimes applied to Bleaching: to remove, lighten or alter natural and cultured pearls, whereby the colour by means of chemical and/or surface of pearls are soaked in warm oil; physical agents or light. to diminish the appearance of cracks. Coating: an artificial layer of any Tinting: a treatment which causes a natural or artificial substance spread subtle change in colour and/or appearance. over the surface, of pearls for protection, colouration, increased lustre and other Waxing: the application of a colourless optical phenomena, decoration or to wax or similar products to, or near, the change appearance; a covering layer. surface of a pearl. Dyeing: any colour caused artificially Working: significantly remove layers by the application of a dye to pearls. of nacreous or non-nacreous material from a pearl, usually to remove blemishes Filling: a substance that occupies and/or to reshape a pearl, especially a whole or part of a void in a pearl. blister pearls.

For more information about CIBJO standards and rules regarding treatments, please download a free pdf copy of the CIBJO Pearl Bluebook: www.cibjo.org

14 CIBJO Retailers’ Reference Guide May 2010 Precious metals Retailers’ Reference Guide precious metals Contents: Precious metals

3 Introduction

4 Common Control Mark

5 Gold

8 Silver

9 Platinum

10 Palladium

The information in the following chapter was provided by the CIBJO Precious Metal Commission with images provided by the World Gold Council and the Platinum Guild International.

All rights reserved. No part of this Guide may be reproduced, republished, amended, translated or changed, including all images included in the Guide, without the express written permission of CIBJO or its authorised agents. Permission to republish, reproduce and/or translate of this Guide is limited to CIBJO member organisations only, and is subject to written agreements between CIBJO and/or its agents and the CIBJO membership organisation.

2 CIBJO Retailers’ Reference Guide May 2010 precious metals Introduction

A precious metal is a rare metallic Marking and Hallmarking Marking As a pre-requisite to official hallmarking, chemical element which is of high the maker or sponsor of a piece Because precious metals are extremely The CIBJO Precious Metals Blue Book economic value. The precious metals are of jewellery must usually mark a expensive, it is very important for stipulates that as an absolute minimum, gold, silver, platinum and palladium in responsibility mark and lodge a claim members of the public and all those all items of jewellery should be stamped their pure state. of fineness. The hallmarking by an assay involved in the jewellery supply chain with a ‘fineness mark’ declaring the office is to confirm this claim. “Assaying” When discussing precious metals, an alloy to know how much precious metal is content of precious metal in the alloy, is the term used to describe the testing is a mixture of metals. So for example, red contained in any precious metal alloy used and a registered ‘responsibility mark’ and measurement of the precious metal gold is an alloy of gold and copper, which for making jewellery. indicating the name of the trader who content in an item such as jewellery. gives the gold its red hue. A precious metal has first placed that piece of jewellery It is impossible for anyone to know how alloy is a solid solution containing at least on the market. National hallmarking systems differ much precious metal there is in a piece one precious metal. from country to country. The Vienna of jewellery simply by looking at it or This mark is not an independent third Convention of 1973 standardised the touching it. The precious metal content party guarantee of the content of the hallmarks, legislation and inspection of must be declared in some meaningful way. precious metal. precious metals in signatory countries to All jewellery should therefore be marked Hallmarking facilitate international trade. Because it or hallmarked with a stamp so that the is so widespread it is the best example to Some countries have independent third consumer knows what they are buying. illustrate how an independent third party party Assay Offices who test precious hallmarking system works. metal jewellery and then strike a ‘Hallmark’ on the article to guarantee Articles which are assayed and found to its’ fineness. be in conformity by the qualifying office of a member country receive a hallmark, A hallmark, is a mark or series of marks known as the Common Control Mark, and struck on items made of precious metals – can be exported and immediately sold in platinum, gold, silver and, in some nations, any of the Convention countries without palladium. Hallmarks are applied by an further testing. assay office and they guarantee a certain purity or fineness of the metal.

3 CIBJO Retailers’ Reference Guide May 2010 precious metals Common Control Mark

The Common Control Mark is a balance and Sweden. scales symbol superimposed on:

Gold: 58 5 Two intersecting circles Silver: 925 The letter “M” Platinum: 900 A diamond shape Palladium: A tent design

4 CIBJO Retailers’ Reference Guide May 2010 precious metals Gold

Gold is a rare metallic element. Its Caratage A caratage value below 24K will indicate chemical symbol, Au, is short for the Latin how much gold there is in the gold Gold jewellery is usually described in word for gold, “Aurum”, which literally jewellery alloy. For instance, 18K is terms of “caratage” (“karatage” in the U.S.) means “Glowing Dawn”. It has several 18/24ths of 100% gold or 75% gold. Many to indicate its gold content. This can also properties that have made it very useful countries only allow certain caratages of be described as fineness which refers to to mankind over the years: gold jewellery to be sold. For example, the parts of gold per thousand by weight. in the United Kingdom one can make and • Pure gold does not rust, tarnish 750 fineness, the measure for 18K gold, sell 9, 14, 18 and 22 carat gold jewellery, or corrode. indicates that there are 750 parts of gold but not 12 carat gold. In some countries, per thousand. 24K gold, which is described • Gold can be melted or shaped jewellery lower than 12 carats (50% gold as “pure gold”, “fine gold” or “Chuk Kam” into almost any design. or 500 fineness) cannot be described as in Chinese, must contain a minimum of gold. The price of gold jewellery is based, • Pure gold has a naturally warm yellow 99.0% gold. in part, on its gold content. Consequently, colour and is one of only two coloured most gold jewellery worldwide is marked metal elements, the other being copper. with its caratage or fineness, often as part All other metals are silver or grey. of the hallmark. • Gold can be alloyed with a number of other metals to increase its strength and create different colours.

5 CIBJO Retailers’ Reference Guide May 2010 precious metals Gold

The following table shows some of the various caratages with their equivalent Carats / Karats Fineness Gold content (%) Comments gold content in percentage and fineness 24 999 99.9 Gold bullion terms, as recognised by law in some countries. 24 990 99.0 Minimum allowed for 24K gold The CIBJO fineness standards recognised 22 916 91.6 Indian subcontinent in the Precious Metals Blue Book are 999; 986; 916; 750; 585; 416; 375; 333. 21 875 87.5 Arabic countries Negative tolerances are not recognised 19.2 800 80.0 Standard in Portugal by CIBJO. 18 750 75.0 Standard caratage

14 585 58.5 583/58.3% in USA

10 417 41.7 Minimum in USA

9 375 37.5 UK standard

8 333 33.3 Minimum in Germany

Elite Designs

6 CIBJO Retailers’ Reference Guide May 2010 precious metals Gold

Colour and finish In addition to different colours, Assaying For this stage, the samples are placed on gold jewellery is available in a range special blocks known as “cupels”. When Gold jewellery can be produced in a range There are numerous methods for of different finishes: heated in a furnace, the cupels absorb of colours – ranging from white, yellow measuring gold content and the choice all of the base metals and the sample is and red, through to blue, black and purple. • Highly polished of method will depend on a number left as just silver and gold. Nitric acid is These variations are achieved by mixing of factors including the accuracy of • Satin-finished or “brushed” then used to dissolve away the silver and (alloying) pure gold with other metals to measurement needed and the speed and the result is a sample of pure gold. This obtain different hues. • Matte-finish ease of measurement. The cost of the is then measured and compared to the equipment (instrument) will also influence White gold is produced by alloying pure • Hammered-finish original weight of the sample. The purity the decision. However, the referee method gold with a family of white metals, most can then be determined from these two • Diamond-cut (featuring tiny, is a process known as cupellation. commonly nickel, palladium and zinc. measurements. reflective facets) Nickel however has properties that cause A sample weighing between 50 - 500 sensitivity and allergies, and needs to be • Diamond-laser (which adds milligrams will be scraped from the item used with great care. In the EU there are extra brightness) to be tested. Highly-sensitive balances are health laws relating to nickel release from used to measure the weight of the sample, • Filigree (a traditional, jewellery. Rose gold is produced by raising which is then bound in lead foil with some intricate appearance) the ratio of copper to silver while green silver. This helps to separate out the base gold is made by adding a combination of metals in the firing stage. silver, palladium and copper to the pure gold. Variations in colour affect other properties of gold such as its hardness and strength.

Cheri Dori

7 CIBJO Retailers’ Reference Guide May 2010 precious metals Silver

Silver has long been valued as a precious Assaying metal and used in currency, ornaments Unlike gold, the usual referee method and jewellery, as well as flatware and for assaying silver is a process known as hollow-ware. It is a soft, white, lustrous “potentiometric titration”. A sample will transition metal and it has the highest be scraped from the item to be assayed electrical and thermal conductivity for which weighs between 50 and 250 a metal. milligrams. The sample is then weighed Sterling silver is an alloy of silver using a highly accurate balance and containing 92.5% pure silver and 7.5% dissolved in nitric acid. other metals, usually copper. In order to determine the silver content, Britannia silver is an alternative potassium chloride is added to the hallmark-quality standard containing sample and the electrical conductivity 95.8% silver, often used to make silver of the solution is tested until the point tableware and wrought plate. that the “titration” is complete and all of the silver has become silver chloride. The Hippocrates, the father of modern amount of potassium chloride needed to medicine, wrote that silver had beneficial get to this point indicates the amount healing and anti-disease properties, and of silver that was in the original sample. the Phoenicians used to store water, wine, and vinegar in silver bottles to prevent spoiling.

8 CIBJO Retailers’ Reference Guide May 2010 precious metals Platinum

Platinum is one of the rarest of the Platinum has a number of other Assaying precious metals, found in only a few places properties that make it an excellent The usual method for assaying platinum worldwide – principally South Africa and catalyst and extremely resistant to is known as inductively coupled plasma- Russia. Naturally white; platinum will not corrosion from most chemicals, which optical emission spectrometry. A sample fade or tarnish – keeping its natural white means that platinum is the only metal of platinum is scraped from the item to colour forever. Most platinum jewellery is suitable for a number of industrial be tested, and then weighed on a highly either 90% or 95% pure, does not need and medical applications ranging from sensitive balance. The next stage is to rhodium plating and being hypoallergenic, catalytic converters to pacemakers. It is dissolve the sample in the appropriate acid will not cause an allergic reaction. The so ductile that one ounce of platinum matrix density of platinum gives it a heft and its can produce a wire over a mile long. ductile nature allows craftsman to create This solution is then passed through the most intricate of jewellery and its The platinum group the spectrometer, which determines physical properties ensure that precious the amount of platinum present in the The platinum group comprises six metallic gemstones are held securely. Although solution as compared to the mass of the elements clustered together in the periodic platinum may scratch like other precious original sample taken. table: ruthenium, rhodium, palladium, metals, minimal metal is lost, being merely osmium, iridium and platinum. Once the purity of the platinum is displaced, so a platinum piece will retain determined, the item will be stamped its metal weight for generations. They are grouped together because they with a hallmark to certify this. have similar chemical properties. For example, they all have catalytic properties however their mechanical properties differ greatly. These metals tend to occur together in the same mineral deposits.

Domino

9 CIBJO Retailers’ Reference Guide May 2010 precious metals Palladium

Palladium is one of the platinum group metals but is considered a precious metal in its own right. Palladium is naturally white which means that there is no need for rhodium plating. Palladium is more precious than silver. It is less dense than platinum, being nearly half the weight, so larger necklaces and bracelets can be made, capable of bearing larger gemstones with minimal gain in overall weight. For the same reason, palladium is considered to be a good choice for earrings although unlike platinum it is not hypoallergenic. It is naturally white, which means there is no need for rhodium plating.

Assaying The usual referee method for assaying palladium is inductively coupled plasma- optical emission spectrometry, the same as for platinum.

10 CIBJO Retailers’ Reference Guide May 2010