Fall 1998 Gems & Gemology
FALL 1998 VOLUME 34 NO. 3 TABLE OF CONTENTS EDITORIAL 157 Demystifying Diamond Cut William E. Boyajian FEATURE ARTICLES 158 Modeling the Appearance of the Round Brilliant Cut Diamond: An Analysis of Brilliance pg. 159 T. Scott Hemphill, Ilene M. Reinitz, Mary L. Johnson, and James E. Shigley 184 Cultured Abalone Blister Pearls from New Zealand Cheryl Y. Wentzell NOTES AND NEW TECHNIQUES 202 Estimating Weights of Mounted Colored Gemstones Charles I. Carmona REGULAR FEATURES 212 Gem Trade Lab Notes 218 Gem News pg. 198 231 1998 Challenge Winners 232 Book Reviews 234 Gemological Abstracts ABOUT THE COVER: Because abalone pearls are admired for their rarity, attractive col- ors, and striking iridescence, efforts have been made to culture them for more than a cen- pg.210 tury. Only recently has commercial production of cultured abalone blister pearls been achieved. A feature article in this issue examines the history, production, marketing, and pg. 217 identifying characteristics of assembled cultured blister pearls from one major producer, Empress Abalone Ltd., using New Zealand’s Haliotis iris. These abalone “mabés” are being incorporated into distinctive jewelry designs, together with colored stones and dia- monds. The gold pendants and rings shown here contain abalone “mabés” ranging from 12.5 to 17.3 mm in diameter. Jewelry courtesy of designer Ian Henderson, Dunedin, New Zealand. 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 Demystifying diamond cut he proper assessment of cut in dia- important appearance concept, bril- We also know that there are many monds has long been an elusive, but liance, based on what the authors call combinations of proportions that yield T intriguing, goal.
[Show full text]