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Finish, Culet Size, and Girdle Thickness: Categories of the GIA Diamond Cut Grading System
Finish, Culet Size, and Girdle Thickness: Categories of the GIA Diamond Cut Grading System This booklet summarizes the relationship of Finish, Culet Size, and Girdle Thickness to the GIA Cut Grading System for round brilliant diamonds. It is intended to help members of the jewelry trade better understand the attributes of diamond appearance, and how those attributes are evaluated within the GIA Cut Grading System. Finish—Polish and Symmetry In the GIA Cut Grading System for standard round brilliant To determine the relationship between finish and overall diamonds, finish (for Polish and Symmetry features) is cut quality, GIA conducted extensive observation testing factored into the final overall cut grade as follows: of numerous diamonds using standardized lighting and viewing conditions. Observations of diamonds with • To qualify for an Excellent cut grade, polish and comparable proportions, but differing in their polish and symmetry must be Very Good or Excellent. symmetry categories, were analyzed to determine the effects of finish on overall cut appearance. In this way, • To qualify for a Very Good cut grade, both polish GIA found that a one grade difference between the other and symmetry must be at least Good. aspects of a diamond’s cut grade and its polish and • To qualify for a Good cut grade, both polish and symmetry assessments did not significantly lower a symmetry must be at least Fair. trained observer’s assessment of face-up appearance, and could not be discerned reliably with the unaided eye— • To qualify for a Fair cut grade, both polish and e.g., polish and/or symmetry descriptions of Very Good symmetry must be at least Fair. -
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. -
IDENTIFYING and VALUING OLD EUROPEAN CUT DIAMONDS Richard B
FEATURE ARTICLE IDENTIFYING AND VALUING OLD EUROPEAN CUT DIAMONDS Richard B. Drucker, GIA GG, Honorary FGA Identifying an old European cut diamond may seem simple but there is a set of GIA standards that determine from their perspective whether it is or is not. This set of standards is not widely accepted by vintage jewelry dealers that struggle with some of the non-calls. For the past several years, prices have risen significantly, sometimes even above the price of a modern brilliant when hard to find and in demand. While that is true in some sizes and qualities, the market is softening in other. uring the past decade, the gemguide has featured will be no cut grade assigned. A polish and symmetry grade several articles on old european cut diamonds. The will still appear. Dfirst article of the same title as this feature here, ap - peared in the November 2010 issue (Volume 29, issue 6). in in our article in 2010, we published the criteria used by the September 2011 (Volume 30, issue 5) another feature article giA to determine if a diamond was to be called old euro - appeared discussing the ongoing dilemma over old european pean cut. They look at four parameters only and today, they cut diamonds, specifically nomenclature on grading reports still consider only those four. Figure 1. The parameters are and the history of cutting styles and cut grading. Today, we as follows. continue to debate nomenclature. Table size: less than or equal to 53% Crown angle: greater than or equal to 40 degrees in November 2012 (Volume 31, issue 6), we published a mar - Lower half facet length: less than or equal to 60% ket trends article showing how the price of these diamonds Culet size: slightly large or larger has continued to rise over the years in comparison to round brilliant cuts. -
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. -
Cover Intro Page Page 1 Page 2 Page 3
by 2018 - 2019 Our apologies in advance for JE9604 $4,125.00 JR6576 $1,785.00 any pricing errors. .75twt diamond earrings, Page 2 .25twt diamond bubble ring, 14k white or yellow gold Cover 14k white or yellow gold JN2744-Y $525.00 .10twt diamond freeform JN962 $2,175.00 JN9604 $3,750.00 JN812 $375.00 pendant, 10k white & yellow .33twt round diamond TRIPLE KEY gold, 18" rope chain Genuine 8x6mm oval .75twt diamond necklace, pendant, 14k yellow gold, amethyst & .10twt 18" cable chain, 14k 18" cable chain JN3410 $ 885.00 diamond necklace, sterling white or yellow gold JE2719-Y $2,550.00 silver, 18" cable chain .12twt diamond bar JN3615 $705.00 .75twt inside-out necklace, 14k yellow Page 1 diamond hoop earrings, gold, 18" cable chain .10twt round brilliant cut set in miracle plates, 10k diamond infinity pendant, Intro Page 10k white or yellow gold, JN425-EM $1,650.00 white or yellow gold JE6109 $1,050.00 18" cable chain. JN9609 $3,750.00 6x4mm pear shaped Genuine 6x4mm oval JN895-Y $1,125.00 .75twt diamond necklace, emerald & .15twt round morganite & .20twt JBBSP304-W .25twt princess & round round diamond earrings, 18" cable chain, 14k diamond pendant, 14k white or yellow gold diamond pendant, 10k 10k rose gold Bezel solitaire round white or yellow gold, 18" white or yellow gold, brilliant cut diamond cable chain. Also available 18" snake chain JN6109 $825.00 pendant, 14k white or yellow JE9609 $4,125.00 gold, 18" cable chain in sapphire or ruby 7x5mm pear shaped .75twt diamond earrings, JN576 .25ct $1,350.00 14k white or yellow gold morganite & .10twt round JE425-EM $2,475.00 Round diamond cluster diamond pendant, 10k rose .33ct $1,785.00 pendant, 14k white gold, 18" cable chain .40ct $2,175.00 JN670-Y $2,175.00 Genuine 5x3mm oval gold, 18" cable chain .50ct $3,375.00 .33twt diamond pendant, emeralds & .30twt round .25twt $975.00 JR6109 $1,050.00 .75ct $6,450.00 18" cable chain, 14k diamond earrings, 14k .50twt $1,905.00 white or yellow gold 7x5mm pear shaped white or yellow gold. -
Gemstones2.Pdf
The Science of Gemology Gemology can be defined as the science of gems. It is most closely Minerals as Gemstones allied with mineralogy, drawing on knowledge of chemistry, physics and geology. Knowledge of physics and chemistry aids in understanding the physical, chemical, and optical properties of minerals. Geological knowledge allows an understanding of the origins and probable natural sources of gemstones. Gemology is not only concerned with the study of natural gem materials, but also with gem testing and evaluation methods, the cutting, polishing and mounting of gem-quality specimens, as well as identification of the distinguishing properties and aesthetic value (grade) of synthetically manufactured gems. Gemologists must also concern themselves with the properties, value and sources of precious metals, as well as the market value of gems and precious metals. What constitutes a gemstone ? Gems traditionally held in highest esteem are diamonds, rubies, “Gemstone” is a collective term for all “stones” used for personal adornment (i.e. as jewelry) or for other ornamental uses. sapphires, emeralds, and some varieties of opal. However, large, high-quality specimens of semiprecious gems (e.g. Tourmaline) The term is usually restricted to “stones” of natural origin, however, often command a very high price even in their natural form. there are “synthetic gems”. Prepared precious gems Not all gemstones are minerals as such (e.g. amber, pearl, coral, jet, opal, ivory, petrified wood). Some are rocks (multimineralic). A “gem” can be thought of as a gemstone that has been cut and/or polished to accentuate its beauty. Gemstones are generally divided into two main categories: Precious gems: characterized by great beauty, durability, stability, large size and rarity. -
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. -
Making Measurements and Using Testing Tools for Specific Properties of Gem Materials Gemstones Are Very Small and Hold Concentra
Making Measurements and Using Testing Tools for Specific Properties of Gem Materials Gemstones are very small and hold concentrated wealth. To correctly identify a cut gemstone may in some instances be much harder than trying to identify a piece of rough material. Many gemstone crystals in rough materials have characteristic crystal shape, cleavage, or fracture, but often you can’t see these properties in cut materials — color, density, luster, reflectivity, heat conduction, magnification, and optical properties are ways to look at cut stones non-destructively and identify them. In this lab we will work with some larger stones and make measurements, Such measurements will be applied to specific stones when we learn gems in a systematic way (as we did with minerals) doing individual groups in labs devoted to them. But for now our goal is to learn the instrumentation, including the names and the parts of the instruments. Importantly, we will learn how to handle the testing equipment in a consistent and practical way so as to avoid any damage to either gemstones or to the testing equipment. Measuring gemstones includes their dimensions, weight (or mass), and describing their color, etc. It is sometimes important in their identification as well, a too heavy feeling gem may not be what it appears to be! Weighing Gemstones First 1 gram is 1/1000 (one one thousandth of a kilogram). The kilogram is defined by a piece of metal held in a laboratory in France. However, a gram is also defined as a milliliter of water at 4oC. These measurement units are part of the International System of Units (abbreviated SI from French: Système international d'unités). -
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.