Making Measurements and Using Testing Tools for Specific Properties of Gem Materials Gemstones Are Very Small and Hold Concentra
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THE CUTTING PROPERTIES of KUNZITE by John L
THE CUTTING PROPERTIES OF KUNZITE By John L. Ramsey In the process of cutting l~unzite,a lapidary comes THE PROBLEMS OF PERFECT CLEAVAGE face-to-face with problem properties that sometimes AND RESISTANCE' TO ABRASION remain hidden from the jeweler. By way of ex- amining these problems, we present the example of Kunzite is a variety of spodumene, a lithium alu- a one-kilo kunzite crystal being cut. The cutting minum silicate (see box). Those readers who are problems shown give ample warning to the jeweler familiar with either cutting or mounting stones to take care in working with kunzite and dem- in jewelry are aware of the problems that spodu- onstrate the necessity of cautioning customers to mene, in this case kunzite, invariably poses. For avoid shocking the stone when they wear it in those unfamiliar, it is important to note that kun- jewelry. zite has two distinct cleavages. Perfect cleavage in a stone means that splitting, when it occurs, tends to produce plane surfaces. Cleavage in two directions means that the splitting can occur in The difficulties inherent in faceting lzunzite are a plane along either of two directions in the crys- legendary to the lapidary. Yet the special cutting tal. The property of cleavage, while not desirable problems of this stone also provide an important in a gemstone, does not in and of itself mean trou- perspective for the jeweler. The cutting process ble. For instance, diamond tends to cleave but reveals all of the stone's intrinsic mineralogical splits with such difficulty that diamonds are cut, problems to anyone who works with it, whether mounted, and worn with little trepidation. -
Blue Sapphire Engagement Ring, RG-2817U Dramatic Color And
Blue Sapphire Engagement Ring, RG-2817u Dramatic color and unusual elegance come together in this vintage style blue sapphire engagement ring. The 18k white gold band of this engagement ring is set along the shoulders and shank with a collection of seventy-four round brilliant cut diamonds that total 0.52 carats. Eight of these diamonds, four on each side, are arranged in a floral design. The diamond flowers flank a bewitching blue sapphire at the center. This is a vintage style (new) blue sapphire engagement ring. Options None Item # rg2817u Metal 18k white gold Weight in grams 4.6 Special characteristics A matching band is available and may be purchased separately. Please see item RG-2817wb. Condition New Diamond cut or shape round brilliant Diamond carat weight 0.52 Diamond mm measurements 1.4-0.9 Diamond color G-H Diamond clarity VS1 Diamond # of stones 74 Gemstone name Natural Corundum (sapphire) Gemstone cut or shape round faceted mixed cut Gemstone carat weight 1.05 Gemstone type Type II Gemstone clarity VS Gemstone hue very very slightly greenish blue Gemstone tone 4-Medium Light Gemstone saturation 4-Moderately Strong Gemstone # of stones 1 Top of ring length (N-S) 6.75 mm [0.26 in] Width of shank at shoulders 4.85 mm [0.19 in] Width of shank at base 2.25 mm [0.09 in] Ring height above finger 6.9 mm [0.27 in] Other ring info For new rings like this one, the gram weight, diamond and gemstone carat weights, color, and clarity, as well as other jewelry details, may vary from the specifications shown on this page, but are similar in quality. -
Evaluation of Brilliance, Fire, and Scintillation in Round Brilliant
Optical Engineering 46͑9͒, 093604 ͑September 2007͒ Evaluation of brilliance, fire, and scintillation in round brilliant gemstones Jose Sasian, FELLOW SPIE Abstract. We discuss several illumination effects in gemstones and University of Arizona present maps to evaluate them. The matrices and tilt views of these College of Optical Sciences maps permit one to find the stones that perform best in terms of illumi- 1630 East University Boulevard nation properties. By using the concepts of the main cutter’s line, and the Tucson, Arizona 85721 anti-cutter’s line, the problem of finding the best stones is reduced by E-mail: [email protected] one dimension in the cutter’s space. For the first time it is clearly shown why the Tolkowsky cut, and other cuts adjacent to it along the main cutter’s line, is one of the best round brilliant cuts. The maps we intro- Jason Quick duce are a valuable educational tool, provide a basis for gemstone grad- Jacob Sheffield ing, and are useful in the jewelry industry to assess gemstone American Gem Society Laboratories performance. © 2007 Society of Photo-Optical Instrumentation Engineers. 8917 West Sahara Avenue ͓DOI: 10.1117/1.2769018͔ Las Vegas, Nevada 89117 Subject terms: gemstone evaluation; gemstone grading; gemstone brilliance; gemstone fire; gemstone scintillation; gemstone cuts; round brilliant; gemstones; diamond cuts; diamonds. James Caudill American Gem Society Advanced Instruments Paper 060668R received Aug. 28, 2006; revised manuscript received Feb. 16, 8881 West Sahara Avenue 2007; accepted for publication Apr. 10, 2007; published online Oct. 1, 2007. Las Vegas, Nevada 89117 Peter Yantzer American Gem Society Laboratories 8917 West Sahara Avenue Las Vegas, Nevada 89117 1 Introduction are refracted out of the stone. -
Carat Weight It's the Old Quandary. Is Bigger Better? Size Is Sought After, Naturally; but Overall Quality Counts in the Stretch
Carat Weight It's the old quandary. Is bigger better? Size is sought after, naturally; but overall quality counts in the stretch. This balance of size and quality makes up much of the art of a professional gem cutter. It is the cutter's job to produce a gorgeous diamond while giving the consumer the highest CARATAGE for his or her money. Caratage means CARAT, the measurement used to weigh a diamond. The word carat is taken from the perfectly matched carob seeds that people once used in ancient times to balance scales. So uniform in shape and weight are these little seeds that even today's sophisticated instruments cannot detect more than three one-thousandths of a difference between them. Don't confuse it with KARAT, the method of determining the purity of gold. What's The Point? One Carat= 200 milligrams, or 0.2 grams. 142 carats adds up to one ounce. Carats are further divided into points. Carat Weight point system What does all this mean, and how does it work? The price of a diamond will always rise proportionately to the size of the stone. Larger diamond crystals are more rare and have a greater value per carat. So, a one carat diamond of a given color and clarity will be much more valuable than 2 one half carat diamonds of equal quality. Cut As the single human contribution to a polished diamond's beauty, cut is perhaps the most important, yet most over-looked, of the Four Cs of diamond quality. How does cut affect a diamond's value and beauty? A good cut gives a diamond its brilliance, its dispersion, its scintillation-in short, its life. -
Cut Shape and Style the Diamond Course
Cut Shape and Style The Diamond Course Diamond Council of America © 2015 Cut Shape and Style In This Lesson: • The C of Personality • Optical Performance • The Features of Cut • The Round Brilliant • Classic Fancy Shapes • Branded Diamond Cuts • Shape, Style, and Cost • Presenting Cuts and Brands THE C OF PERSONALITY In the diamond industry the term “cut” has two distinct meanings. One is descriptive. It refers to the diamond’s shape and faceting style. The other relates to quality, and includes proportions, symmetry, and polish. Most customers are familiar with only the first meaning – cut shape and style. That’s the aspect of All sorts of cutting shapes are cut you’re going to examine in this lesson. The next possible with diamonds. lesson explores the second part of this C. For many customers, cut shape and style is part of their mental image of a diamond. Shape contrib- utes to the messages that a diamond sends about the personality of the one who gives or wears it. When presenting this aspect of cut, you need to match the images and messages of the diamonds you show with the customers you serve. With branded diamond cuts, you may need to explain other elements that add appeal or value. When you’ve accomplished these objectives you’ve taken an important step toward closing the sale. The Diamond Course 5 Diamond Council of America © 1 Cut Shape and Style Lesson Objectives When you have successfully completed this lesson you will be able to: • Define the optical ingredients of diamond’s beauty. • Describe diamond cuts in understandable terms. -
Ruby and Diamond Engagement Ring, RG-2408 the 18K White Gold Band of This Ruby Engagement Ring Is Set Three-Quarters of The
Ruby and Diamond Engagement Ring, RG-2408 The 18k white gold band of this ruby engagement ring is set three-quarters of the way around with sixty round full cut diamonds weighing 0.77 carats. The diamonds are dazzling against the brilliant color of the ruby. This round faceted mixed cut ruby weighs 1.05 carats. This is a new ruby and diamond engagement ring. Options None Item # rg2408 Metal 18 karat white gold Weight in grams 4.06 Condition New Diamond cut or shape round full cut Diamond carat weight 0.77 Diamond mm measurements 1.0 to 2.7 Diamond color G and H Diamond clarity VVS1 to VS2 Diamond # of stones 60 Gemstone name Natural Corundum (Ruby) Gemstone cut or shape round, faceted mixed cut Gemstone carat weight 1.053 Gemstone mm measurements 6.26 - 6.31 x 3.32 Gemstone type Type II Gemstone clarity SI2 Gemstone hue very, very slightly purplish red Gemstone tone 4.-5 Gemstone saturation 4-Moderately Strong Gemstone # of stones 1 Top of ring length (N-S) 6.20 mm [0.24 in] Top of ring width (E-W) 17.78 mm [0.69 in] Width of shank at shoulders 2.48 mm [0.10 in] Width of shank at base 2.37 mm [0.09 in] Ring height above finger 7.53 mm [0.29 in] Ring Size 6.5 Important Jewelry Information Each antique and vintage jewelry piece is sent off site to be evaluated by an appraiser who is not a Topazery employee and who has earned the GIA Graduate Gemologist diploma as well as the title of AGS Certified Gemologist Appraiser. -
The Ideal Brilliant Cut: Its Beginnings to Today
MICHAEL D. COWING is the author of Objective Diamond Clarity Grading, an educator, gemologist and appraiser operating an Accredited Gemologist Association Certified Gem Laboratory. His career in diamonds, gems, and gemology spans 35 years. The Ideal Brilliant Cut: Its Beginnings to Today Figure 1. Face-up view of the Ideal Figure 2. 20° Tilt from face-up Figure 3. 20° Tilt forward from the side Cut at its beginning in the 1860’s view of the early Ideal Cut. view of the early Ideal Cut. time frame. Figure 4. Face-up view of today’s Figure 5. 20° tilt from face-up Figure 6. 20° tilt forward from the side view Ideal Cut with fundamentally the view of today’s Ideal Cut. of today’s Ideal Cut. same main angles as the early Ideal. Introduction back angle1.“ It was also known in Europe around the turn of the 19th century as the American Cut. The Ideal Cut’s Since its beginnings in the early 20th century to the present appearance is transformed in Figures 4-6 with today’s day, confusion and misunderstanding has frequently proportions, (larger table size, longer lower girdle facets, surrounded the use (or misuse) of the term “Ideal Round thicker girdle, etc.), while retaining the same fundamental Brilliant Cut,” its defining properties and origin. Some have crown and pavilion main angles which are key to its beauty. advocated eliminating its use altogether. Through the examination of the Ideal Round Brilliant Cut’s (Ideal Cut The Ideal’s beginning with the American Cut hereafter) evolution, this article endeavors to clear up its history, clarify its defining properties and in the process The beginning of today’s Ideal Round Brilliant Cut was the dispel the misunderstanding and mythology surrounding this design attributed to Henry Morse and his diamond cutting most popular of diamond cuts. -
Winter 1998 Gems & Gemology
WINTER 1998 VOLUME 34 NO. 4 TABLE OF CONTENTS 243 LETTERS FEATURE ARTICLES 246 Characterizing Natural-Color Type IIb Blue Diamonds John M. King, Thomas M. Moses, James E. Shigley, Christopher M. Welbourn, Simon C. Lawson, and Martin Cooper pg. 247 270 Fingerprinting of Two Diamonds Cut from the Same Rough Ichiro Sunagawa, Toshikazu Yasuda, and Hideaki Fukushima NOTES AND NEW TECHNIQUES 281 Barite Inclusions in Fluorite John I. Koivula and Shane Elen pg. 271 REGULAR FEATURES 284 Gem Trade Lab Notes 290 Gem News 303 Book Reviews 306 Gemological Abstracts 314 1998 Index pg. 281 pg. 298 ABOUT THE COVER: Blue diamonds are among the rarest and most highly valued of gemstones. The lead article in this issue examines the history, sources, and gemological characteristics of these diamonds, as well as their distinctive color appearance. Rela- tionships between their color, clarity, and other properties were derived from hundreds of samples—including such famous blue diamonds as the Hope and the Blue Heart (or Unzue Blue)—that were studied at the GIA Gem Trade Laboratory over the past several years. The diamonds shown here range from 0.69 to 2.03 ct. Photo © Harold & Erica Van Pelt––Photographers, Los Angeles, California. Color separations for Gems & Gemology are by Pacific Color, Carlsbad, California. Printing is by Fry Communications, Inc., Mechanicsburg, Pennsylvania. © 1998 Gemological Institute of America All rights reserved. ISSN 0016-626X GIA “Cut” Report Flawed? The long-awaited GIA report on the ray-tracing analysis of round brilliant diamonds appeared in the Fall 1998 Gems & Gemology (“Modeling the Appearance of the Round Brilliant Cut Diamond: An Analysis of Brilliance,” by T. -
Winter 2009 Gems & Gemology
G EMS & G VOLUME XLV WINTER 2009 EMOLOGY W INTER 2009 P AGES 235–312 Ruby-Sapphire Review V Nanocut Plasma-Etched Diamonds OLUME Chrysoprase from Tanzania 45 N Demantoid from Italy O. 4 THE QUARTERLY JOURNAL OF THE GEMOLOGICAL INSTITUTE OF AMERICA EXPERTISE THAT SPREADS CONFIDENCE. Because Public Education AROUND THE WORLD AND AROUND THE CLOCK. Happens at the Counter. ISRAEL 5:00 PM GIA launches Retailer Support Kit and website Cutter checks parameters online with GIA Facetware® Cut Estimator. NEW YORK 10:00 AM GIA Master Color Comparison Diamonds confirm color quality of a fancy yellow. CARLSBAD 7:00 AM MUMBAI 7:30 PM Laboratory technicians calibrate Staff gemologist submits new findings on measurement devices before coated diamonds to GIA global database. the day’s production begins. HONG KONG 10:00 PM Wholesaler views grading results and requests additional services online at My Laboratory. JOHANNESBURG 5:00 PM Diamond graders inscribe a diamond and issue a GIA Diamond Dossier® A $97.00 value, shipping and handling extra. All across the planet, GIA labs and gemological reports are creating a common language for accurate, unbiased gemstone GIA’s Retailer Support Kit has been developed to help evaluation. From convenient locations in major gem centers, to frontline detection of emerging treatments and synthetics, to online services that include ordering, tracking, and report previews — GIA is pioneering the technology, tools and talent sales associates educate the public about diamonds, that not only ensure expert service, but also advance the public trust in gems and jewelry worldwide. the 4Cs, and thoroughly explain a GIA grading report. -
Investing in Colored Diamonds from Diamond Investment Dealers
BENEFITS OF INVESTING IN COLORED DIAMONDS FROM DIAMOND INVESTMENT DEALERS When investing in diamonds you need an ad- ly appreciated in value. Over the last decade, visor who has the depth and breadth of knowl- Argyle pink diamonds have consistently bro- edge in investment grade diamonds. Rare ken records on the global auction market, Diamond Investor provides seamless access demonstrating the robust nature of the dia- for savvy investors. We focus exclusively on mond market and the unceasing international natural fancy-colored diamonds and are staffed demand. Christies auctions have surpassed by experts in every facet of the diamond mar- records the last few years for both the most ket. This level of experience and expertise not expensive investment grade diamonds and only gives us greater understanding of the di- the highest price per carat. In April 2014, Chris- amond market, but also gives us access to a ties auctioned top quality, fancy pink, blue professional global network of investors, col- and yellow diamonds with prices exceeding of lectors and industry specialists including the $1 to $2 million per carat, leading Christies most sought after gemologists and diamond to declare 2014 the year of the colored dia- cutters in the world. mond. Rahul Kadakia, Head of Christies New York, states, At a time when other investments have suf- fered unparalleled chaos and uncertainty, “A colorless D-grade diamond at auction will make about $150,000 a carat, while a pink natural fancy-colored diamonds have steadi- fancy-colored diamond will make $1.5 million a carat, 10 times the price.” He also stated, “This is where the market is. -
Gem Diamonds: Causes of Colors
New Diamond and Frontier Carbon Technology Vol. 17, No. 3 2007 MYU Tokyo NDFCT 536 Gem Diamonds: Causes of Colors Hiroshi Kitawaki Gemmological Association of All Japan, Ueno 5-25-11, Taito-ku, Tokyo 110-0005, Japan (Received 9 May 2007; accepted 1 August 2007) Key words: gem, natural diamond, color, treatment Diamonds for gem use are colorless in general, but some stones with bright colors are highly valued as fancy color diamonds. The body color of diamond depends on the concentration of nitrogen and the form of aggregation. Structural defects and vacancy bonding may also cause color centers. Furthermore, plastic deformation may bring DERXWFRORU5HFHQWO\DUWL¿FLDOFRORULQJWRLQWHQWLRQDOO\SURGXFH³IDQF\FRORU´VWRQHV has been carried out on a commercial basis. The combined process of electron beam irradiation with annealing and the high-pressure high-temperature (HPHT) process are quite common treatment techniques today. Leading gem laboratories around the world are currently working on these tasks to establish techniques, with a few exceptions, for revealing the origin of the color of the diamond. 1. Introduction Diamond quality as a gemstone is generally graded by the four Cs. Diamonds of a FHUWDLQFDUDWZLWK¿QHFXWDQGFODULW\JUDGHVYDU\ODUJHO\LQYDOXHDFFRUGLQJWRWKHLUFRORU $SHUIHFWGLDPRQGLVWKHRUHWLFDOO\FRORUOHVVWUDQVSDUHQWDQGVKRZVQRÀXRUHVFHQFH to UV light. In nature, however, even an almost perfect crystal is very rare; hence, it is highly evaluated. Commercially available gem diamonds often show a slightly yellow tint that is derived from a nitrogen-related defect. As the yellow tint becomes more intense, the value of a stone is generally lowered, but other colors such as pink, green or blue are valued for the color itself as fancy color diamonds, and there is a market for such diamonds. -
Diamond Buying Guide
SELECTING A DIAMOND PROTECT YOUR DIAMOND OUR GIA GEMOLOGIST DISTINCT ELEGANT TIMELESS HOW A DIAMOND IS GRADED TIPS TO SAFEGUARD YOUR DIAMOND VICTORIA KING, GIA GG Not all diamonds are created equal. Every • Choose a secure setting. Vicki is a graduate of the prestigious diamond is unique. Diamonds come in • Keep your diamond clean. Gemological Institute of America. She is many sizes, shapes, colors, and with various a highly skilled gemologist who has the • Place your diamond in a jewelry box or other internal characteristics. At King Jewelers, technical knowledge needed to grade and safe place when you are not wearing it. we use the grading system developed by the determine diamond quality as well as the Gemological Institute of America in the 1950’s • We recommend getting a professional cleaning value of other gemstones. Vicki brings which established the use of four important and inspection every 6 months. more than 40 years of skill and expertise factors to describe and classify diamonds: • Have your diamond appraised and insured. to her work, and operates a full service Clarity, Color, Cut, and Carat Weight. gem laboratory on the premises. “We guarantee the grading of your Your diamond may be The distinguished GIA GG designation is diamond’s color, clarity and carat the most expensive stone instantly recognized around the world as weight to be at least as good as you ever buy. Most likely, the mark of a senior professional in the Understanding we promised you and to be in you will wear your diamond every day so jewelry industry. accordance with the guidelines the odds are high that you could misplace or the Value of of the Gemological Institute even lose you diamond.