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News Releases
Fall 2004 Issue Features Evaluation of Diamond Cut
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Gems & Gemology has released its Fall 2004 edition. Highlighting this groundbreaking issue is the third installment of GIA’s research on diamond cut.
With the lead article, “A Foundation for Grading the Overall Cut Quality of Round Brilliant Cut Diamonds,” Thomas M. Moses and a host of GIA colleagues present the results of their latest research on the proportion factors that affect overall cut appearance and quality of the standard round brilliant. For this study, the authors conducted extensive visual observation testing on actual diamonds for brightness, fire, and overall cut appearance. On the basis of their findings, the team constructed the foundation for the GIA diamond cut grading system, which will provide a single overall grade for cut quality for standard round brilliants. This system will be incorporated into the Institute’s educational programs and diamond-grading services in 2005.
“The diamond cut article is the product of a truly monumental research effort,” said G&G Editor-in-Chief Alice S. Keller. “The first two articles in the series [from the Fall 1998 and Fall 2001 issues] used computer modeling to predict brilliance and fire based on various combinations of cut proportions. This new study involved more than 70,000 visual observations by trade professionals as well as consumers to refine the brilliance (now more appropriately referred to as 'brightness') and fire metrics and explore other aspects of the complex relationship between diamond cut and appearance.”
Accompanying the diamond cut article is a pull-out chart that shows examples from each of the five categories in the GIA diamond cut grading system. Another unique feature of the Fall issue appears on the cover itself: a lenticular image that projects a single round brilliant as it moves through five different viewing angles.
Also in this issue is an article by Jack Lowell and John I. Koivula, “Amethyst from Four Peaks, Arizona,” which looks at the geology, mining, and gemological properties of amethyst from the most important commercial source in the United States.
The Lab Notes column features the latest from the GIA Gem Laboratory, including rubies that had been clarity enhanced with a lead-based glass filler and a gemological examination of four blue diamonds from the historic Cullinan blue diamond necklace. Meanwhile, the Gem News International section covers the world of gemology, with reports on rhodonite from Brazil, spessartine and hessonite from Afghanistan, tourmaline from the Democratic Republic of the Congo, and more. Rounding out the Fall issue are the Book Reviews and Gemological Abstracts sections, plus the list of winners from this year’s Gems & Gemology Challenge quiz.
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