EDITORIAL Editor-in-Chief Editor Editor, Gem Trade Lab Notes STAFF Richard T. Liddicoat Alice S. Keller C. W. Frver Associate Editors I660 Stewart St. Editor, Gemological Abstracts Santa Monica, CA 90404 Peter C. Keller Dona M. Dirlam Telephone: (800)421-7250 x25 1 D. Vincent Manson Editor, Book Reviews John Sinltankas Subscriptions Elise B. Misiorowslzi Lisa Hebenstreit, Manager Technical Editor Bruce Tucker, Asst. Manager Contributing Editor, John I. Koivula Carol M. Stockton Telephone: [800! 421-7250 x201 Editors, Gem News Editorial Assistant John I. Koivula Nancy K. Hays Robcrt C. Kammerling PRODUCTION Jennifer Brosious Julie Matz Cccile Miranda STAFF Linda Manion Patricia Mayer Ruth Patchick Susan Kingsbury Jan Newcll Peter Johnston EDITOR14 William E. Boyajian Robcrt C. Kammerling Sallie Morton REVIEW BOARD Sonto Monico, CA Sontrl Monico. CA San lose, CA Robert Crowningshield Anthony li. Kampf Kurt Nassau New York, NY Los Angeles, CA Bernardsvllle, N/ Dennis Foltz Robert E. K~ne Ray Page Santo Monica, CA Los Angeles, CA Santa iMonlco, CA C. W. Fryer John I. Koivula George Rossman Santa Monica, CA S~ntrl/Monica, CA Posodenn, CA C. S. Hurlbut, Jr. Henry 0. A. Meycr James E. Shiglcy Cambridge, IMA West Lalayette, IN Sonia ~Monlca,CA SUBSCRIPTIONS Subscrip~ionsin the U.S.A. are priced as follows: $32.95 for onc ycar (4 issues), $89.95 for thrce ycars (12 issues) Subscriptions sent clscwherc arc S42.00 for onc year, S120.00 for three years. Special a~inualsubscripti011 rates are available for all students actively involved in a GIA program: $29.95 U.S.A., $39.00 elsewhere. Yoor student number must be listed at the time your subscription is entcred. Single issues may be purchased for S8.50 in the U.S.A., $1 1.50 elsewhere. Discounts are given for bulk orders of 10 or more of ally one issue. A limited nomber of back issues of G&G are also available for purchase. Please address all inquiries regarding subscriptions and the purchase of single copies or back issues to the Subscriptions Manager. For subscriptions and back Issues in Italy, please contact Istituto Gemmologico ~Mediterraneo,Via Marmola~a#14, 1-38033, Cavalese TN, Italy. To obtain a Japanese translation of Gems d Gemology, contact the Association of Japan Gem Trust, Okachimachi Cy Bldg, 5-15-14 Ueno, Taito-ku, Tokyo 110, Japan. MANUSCRIPT Gems Gemology welcomes the submission of articles on all aspects of the field. Please see the Suggestions SUBMISSIONS for Authors in the Fall 1987 issue of the journal, or contact the edi~orfor a copy. Letters on articles published in Gems d Gernology and other relevant matters are also welcome. COPYRIGHT Abstracting is permitted with credit to the source. Libraries are permitted to photocopy beyond thc limits of U.S. AND REPRINT copyright law for private use of patrons. Instructors are permitted to photocopy isolated artlcles for noncom~nercial PERMISSIONS classroom use without fee. For other copying, reprint, or republication permission, please coiltact thc Editor. Gerns d Gemology is published quarterly by the Gemological Institute of Amcrica, a nonprofit educational organization for the jewelry industry, I660 Stewart St., Santa ~Monica,CA 90404. Postmaster: Return undeliverable copies of Gems 01 Ge~nologyto I660 Stewart St., S:~nta Mon~ca,CA 90404. Any opin~onscxpressed In slgned art~clcsare undcrs~oodto be the vlews of the authors and not of thc publ~shers. SPRING 1988 Volume 24 Number '1 TABLE OF CONTENTS EDITORIAL 1 Retrospective 1987lThe Gems & Gemology Most Valuable Article Award Alice S. Ikller FEATURE 3 An Update on Color in Gems. ARTICLES Part 2: Colors Involving Multiple Atoms and Color Centers Emmonuel Fritsch and George R. Rossmon 16 Chrysoberyl and Alexandrite from the Pegmatite Districts of Minas Gerais, Brazil Keith Proctor 33 Faceting Large Gemstones Michoel Gray NOTES 44 The Distinction of Natural from Synthetic AND NEW Alexandrite by Infrared Spectroscopy TECHNIQUES Carol M. Stockton and Robert E. Kane REGULAR 47 Gem Trade Lab Notes FEATURES 54 Gems & Gemology Challenge 56 Gem News 60 Book Reviews 62 Gemological Abstracts ABOUT THE COVER: This 175-ct sapphire is exceptional for both its color nntl its size. The blue color is the result of I:e2++TP+ intervnlence charge trnnsfer, one of the color-crrusing mechnnisrns discussetl in the secontl article of n three-port series on color in gemstones. In this issue, Drs. Fritsch nl~dRoss~nan review cnuses of color that involve more than one atom, ns well ns those brought about by various defects. The snpphire pendnnt, set with 17 ct of diamonds oncl suspended from a necltlnce of 8-8.5 mm cultured penrls, is courtesy o/ Roger Farr-Pnrk/Allbritton. Photo O Hnrold el Ericn Von Pelt-Photographers, Los Angeles, CA. Typesetting for Gems Ck Gemology is by Sclcntific Composition, Los Angeles, CA. Color separations are by Effective Graphics, Compton, CA. Printing is by Wuverly Press, Easton, MD. 8 1988 Gemological Institute of America All rights reserved ISSN 001 6-626X RETROSPECTIVE 1987 Undeniably, 1987 was yet another watershed year in gemology. In diamonds, a 0.95-ct fancy purplish red round brilliant-cut sold for $880,000-a record per-carat price of $926,000. I11 synthetic diamonds, not only did the first Sumitomo gem-quality synthetic diamonds appear on the gem marlzet, but De Beers released information revealing just how far their experiments with gem-quality synthetic diamonds had progressed; one such crystal tipped the scale at over 11 ct. Perhaps the biggest news in colored stones last year was the discovery of a major find of superb alexandrites near the town of Hematita in Minas Gerais, Brazil; in less than three months in 1987, more than 50 kg of gem-quality alexandrites were taken from this small deposit before it was closed because of the violence that ensued. As for synthetic colored stones, producers continue to proliferate and even materials such as malachite are no longer beyond our technical capabilities. To help in the continuing battle to identify new synthetics and gein treatments as soon as they emerge on the marlzet, sophisticated technology such as infrared spectroscopy is now being applied to a wide variety of gemological problems. All of these topics, and many others, were covered in the 1987 volume of Gems d Gemology And a detailed description of the remarkable Heinatita alexandrite find is provided in this issue. We are pleased that Gems d Gemology continues to be, in the words of one of our readers, "absolutely essential to anyone in the busineps of jewelry." We would lilze to thank the inembers of our editorial review board, our very special section and techscal editors, and the photographers and graphic artists who are responsible for building this' rkputation. THE GEMS & GEMOLOGY MOST VALUABLE ARTICLE AWARD We are also pleased to have this opportunity to recognize some of the many authors who, in 1987, helped inalze Gerns d Gemology such a vital information source. The overwhelming choice of our readers for first place in the most valuable article award is "Gemstone Durability: Design to Display," by Deborah Martin. The response to this article was so strong that GIA has now released a laminated version of the chart of durability considerations for 31 gem species. Second place goes to the first in a three-part series that seelzs to explain, in terms that the jeweler/gen~ologistcan readily understand, the causes of color in gem materials: 'An Update on Color in Gems. Part 1: Introduction and Colors Caused by Dispersed Metal Ions," by Emmanuel Fritsch and George Rossman. The current importance of yellow sapphire and the questions regarding its color stability were evident in the selection of the third-place article: "The Seven Types of Yellow Sapphire and Their Stability to Light," by Kurt Nassau and G. Kay Valente. Cash prizes of $500, $300, and $100, respectively, will be shared by the authors of the first-, second-, and third-place articles. Brief biographies of the winning authors appear on the following page. Alice S. Keller, Editor Editorial GEMS 6: GEMOLOGY Spring 1988 1 THE WINNERS DEBORAH DUPONT MARTIN Ms. Martin began her jewelry career in retail sales and management, but quickly realized that her real interest was design and manufacturing. After several years as a bench jeweler, her love of gemstones brought her to the Gemological Institute of America, Santa Monica, where she received her Graduate Gemologist degree and subsequently taught in the Colored StonesIGem Identification Department of the Resident Program. A native of Oklahoma, Ms. Martin is currently a staff gemologist with the GIA Gem Trade Laboratory, Inc., Los Angeles. EMMANUEL FRITSCH Dr. Fritsch studied engineering geology in Nancy, in eastern France, before moving to Paris, where he received his Ph.D. at the Sorbonne. He is currently a research scientist at GIA Santa Monica. A gemstone enthusiast for many years, Dr. Fritsch's research specialities are twinned crystals and the origin of color in gem materials. GEORGE R. ROSSMAN Dr. Rossman received his B.Sc. degree from Wisconsin State University, Eau Clair, and his Ph.D. (in chemistry] from the California Institute of Technology, 13asadena, where he is now professor of mineralogy. His current research studies involve the origin of color phenomena in minerals and the physical and chemical properties of minerals. He is also investigating how long-term natural background radiation can affect minerals. KURT NASSAU Dr. Nassau's work at the Materials Laboratory of AT&T Bell Laboratories includes active involvement in research on crystal growth and the chemistry of solid-state materials. Currently, Dr. Nassau is studying quenched and conventional glasses and crystals for electronic and fiber-optic applications as well as high-temperature superconductors.