Fall 1996 Gems & Gemology
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.
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