VOLUME XXXII FALL 1996 THE QUARTERLY JOURNAL OF THE GEMOLOGICAL INSTITUTE OF AMERICA - -' ' ii2 -.F..Ñ[. 1 . :'^ . i':..>ib,:, Q*.,:. ;: ,* ; , ,<, ; . i -..,,,, .t , ,:Ah' f I 8 ., * - + ;.<' , . *- . ' ..1 V ' ,: ' i . , : < , ''; > GEMS&'. ,' :, . , -v ,.. r , . .. + , . , ' . ... ..] . <.^ -..t.*' -( ",i ' . ' . ., ALL^ 996;. ,, -, ,GEb.OLOGy.i~.-..,,,>*- VOLUME 32 NO. 3 1 TABL CON 15 3 EDITORIAL Opening Pandora's Black Box Richard T. Liddicoat, Editor-in-Chief LETTERS FEATURE ARTICLES De Beers Natural versus Synthetic Diamon Verification Instruments Christopher M.Welbourn, Martin Cooper, and Paul M. Spear Introduction to Analyzing Internal Growth Structures: Identification of the Negative d Plane in Natural Ruby Christopher P. Smith Russian Flux-Grown Synthetic Alexandrite Karl Schmetzer, Adolf Peretti, Olaf Medenbach, and Heinz-Jvrgen Bernhardt REGULAR FEATURES pg. 176 1996 Challenge Winners Gem Trade Lab Notes Gem News Book Reviews Gemological Abstracts ABOUT THE COVER: Responding to trade concerns about the possible cominer- cia1 availability of cuttable-quality synthetic diamonds, De Beers researchers in pg. 187 Maidenhead, England, have developed two types of machines-the DiamondSure and the DiamondView-to separate natural from synthetic diamonds. These new instruments are the focus of the lead article in this issue, by Christopher Welbourn, Martin Cooper, and Paul Spear. The natural-diamond rings shown here contain round brilliants weighing a total of 5.19 ct (top), 4.38 ct (left),5.36 ct (bottom), and (right)6.78 ct with a 3.49 ct yellow emerald-cut diamond. Courtesy of Hans D. Krieger, Idar-Obatstein, Germany, Photo 0 Harold &> Erica Van Pelt-Photographers, Los Angeles, CA Color separations for Gems & Gemology are by Effective Graphics, Co~npton,CA. Printing is by Cadmus journal Services, Baltimore, MD. 0 1996 Gemological Institute of America All rights reserved ISSN 0016-626X Editor-in-Chief Editor Editor, Gem Trade Lab Notes Richard T. Lidclicoat Alice S. Keller C. W. Fryer 1660 Stewart St. Associate Editors Santa Monica, CA 90404 Editors, Gem News William E. Boyajian (310) 829-2991 x251 Mary L. Johnson D. Vincent Manson e-mail: [email protected] John 1. Koivula John Sinkankas Subscriptions Editors, Book Reviews Technical Editor Jin Lim Cristina Chavira Susan B. Johnson Carol M. Stockton (800)421-7250 x201 Jana E, Miyahira Fax: (310)453-4478 Senior Editor Irv Dierdorff Contributing Editor Editor, Gemological Abstracts e-mail: [email protected] John I. Koivula C. W. Fryer PRODUCTION Art Director Production Assistant STAFF Christine Troianello Gail Young EDITORIAL Alan T. Collins C. S. Hurlbut, Jr. Kurt Nassau REVIEWBOARD Lor~don,United Kingdom Cambridge, Massachusetts P.O. Lebanon, New Jersey G. Robert Crowningshield Alan Jobbins George Rossinan New York, New York Caterham, United Kingdom Pasadena, California John Emmett Anthony R. Kampf Kenneth Scarratt Rush Prairie, Washington Los Angeles, California Bangkok, Thailand Emmanuel Fritsch Robert E. Kane Karl Schmetzcr Nan tes, France Helena, Montana Petershausen, Germany C. W. Fryer John I. Koivula James E. Shigley Santa Monica, California Santa Monica, California Santa Monica, California Henry A. Hanni A. A. Levinson Christopher P. Smith Basel, Switzerland Calgary, Alberta, Canada Lucerne, Switzerland SUBSCRIPTIONS Subscriptions in the U.S.A. are priced as follows: $59.95 for one year (4 issues), $149.95 for three years (12 issues]. Subscriptions sent elsewhere are $70.00 for one year, $180.00 for three years. Special annual subscription rates are available for all students actively involved in a GIA program: $49.95, U.S.A.; $60.00, elsewhere. Your student number must be listed at the time your subscription is entered. Single issues may be purchased for $15.00 in the U.S.A., $18.00 elsewhere. Discounts arc given for bulk orders of 10 or more of any one issue. A limited number of back issues of Ga)C are also available for purchase. Please address all inquiries regarding subscriptions and the purchase of single copies or back issues to the Subscriptions Dcpaitrnent. To obtain a Japanese translation of Gems ei> Gemology, contact the Association of Japan Gem Trust, Okachimachi Cy Bldg., 5-15-14 Ueno, Taito-ku, Tokyo 110, Japan. Our Canadian goods and service registration number is 126142892RT. MANUSCRIPT Gems o) Gemology welcomes the submission of articles on all aspects of the field. Please see the Guidelines for Authors in the Summer 1996 issue of the journal, or contact the editor for a copy. Letters on articles published in SUBMISSIONS Gems ed Gemology and other relevant matters are also welcome. COPYRIGHT Abstracting is permitted with credit to the source. Libraries are permitted to photocopy beyond the limits of U.S. AND copyright law for private use of patrons. Instructors are permitted to photocopy isolated articles for noncommercial REPRINT classroom use without fee. Copying of the photographs by any means other than traditional photocopying tech- PERMISSIONS niques (Xerox, etc.) is prohibited without the express pern~issionof the photographer (where listed) or author of the article in which the photo appears (where no photographer is listed). For other copying, reprint, or republication per- mission, please contact the editor. Gems o) Gemology is published quarterly by the Gemological Institute of America, a nonprofit educational organi- zation for the jewelry industry, 1660 Stewart Street, Santa Monica, CA 90404. Postmaster: Return undeliverable copies of Gems a> Gemology to 1660 Stewart Street, Santa Monica, CA 90404. Any opinions expressed in signed articles are understood to be the opinions of the authors and 1101 of the publishers. BLACKBox - Richard T Liddicoat, Editor-in-Chief In this era of increasingly sophisticated synthetic materials and forms of enhancement, gemologists need every possible weapon in their testing arsenal. To this end, this issue of Gems &> Gemology offers two articles relating to new methods of identification. One describes two instruments designed by De Beers researchers to help identify synthetic dia- inonds. These instruments successfully address a need and desire for quick, easy, and reli- able diamond testing in a fast-paced, competitive world. Thus, they represent a growing trend in gemology toward "black box" methodology, which can be practiced with a mini- mum of skill and technical knowledge. Although such instruments provide a great service to our industry, there are some problems for which no "black box" may ever be available, that to date have been solved only by using expensive instrumentation in a well-staffed laboratory. Foremost among these are the separation of some natural and synthetic rubies, sapphires, and emeralds. The second article, by the Gubelin Laboratory's Christopher Smith, involves an identification technique that may seem esoteric to some readers, but is actually closer to "grass roots" gemology. Internal growth-structure analysis (that is, analy- sis of features such as twinning and crystal planes within a cut natural or synthetic stone that reflect its distinctive growth history) requires relatively little new equipment. It does, however, call for the unique talents of the professional gemologist. There are many levels of need among gemologsts. Those operating in a well-financed test- ing laboratory may have the resources and space to consider X-ray, ultraviolet, infrared, and Raman spectroscopy-and/or other systems costing $100,000 or more. A well-equipped elec- tron rnicroprobe can cost over a million dollars. Most gemologists, however, have neither the finances nor the space to consider much more than a binocular microscope, refractome- ter, polariscope, desk-model spectroscope, and a few other relatively small and inexpensive items. As recently as the middle of this century, amateur gemologist Count E. C. R. Taaffe recognized that he had something hitherto unknown-the first taaffeite-using only a loupe and other rudimentary equipment. He lacked even a refractometer. Although any gemologist with access to extensive testing instrumentation may benefit from internal growth-structure analysis, it is of particular value to the gemologist in the office, the jewelry store, the small laboratory. First introduced to gemology by Karl Schmetzer, its advantage is that it requires only a binocular microscope and a few acces- sories that can be purchased or even created by modifying equipment on hand. Such a method may require extensive and time-consuming "jury-rigging" (at relatively minor expense), but it can yield information as essential as that provided by the most sophisticat- .ed instrumentation. However, it depends heavily on the most important of all gemological tools: the gemologist's own knowledge, skill, and meticulous practice in testing. We can be thankful whenever a veritable "black box" is designed to meet one of our test- ing challenges. But when none is available, there is no substitute for creative gemology. 0 Editorial GEMS & GEMOLOGY Fall 1996 153 THE OBSERVATION OF MAGNETISM Dr. Jeff Harris, at Glasgow University, indicated IN SYNTHETIC DIAMOND that the iron sulphide minerals pyrrhotite and pent- landite would show a magnetic response in a natur- "A Chart for the Separation of Natural and Synthetic al diamond, and together we observed the slightest Diamonds," by J. Slugley et al. [Winter 1995, pp. of responses from such mineral inclusions in natur- 256-2641 is one of the jewelry trade's most useful ref- al diamond when the stone was floated on a tiny (5 erence aids. The article dealt with the range of indica- x 5 mm) polysterene raft. Fortunately for the gemol- tor tests available to the jeweler/gemolo~st,one of ogist, such inclusions are black, and they are almost which is magnetism. The article spawned two always accompanied by stress fractures that are also responses, which were published in the Spring 1996 filled with black mineral films. (Metallic inclusions "Letters" section (p.63). Both Dr. Hanneman's original in synthetic diamonds do not exhibit stress frac- letter and the reply by GIA Gem Trade Laboratory tures.) Even when large, such natural inclusions Vice-president Tom Moses describe methods for produce only the slightest response.