Feature Gems & Gemology, Fall 1999, Volume 35, No. 3

Observations on GE-Processed Diamonds: A Photographic Record

Thomas M. Moses, James E. Shigley, Shane F. McClure, John I. Koivula, and Mark Van Daele

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As of august 1999, GIA staff members had examined 960 natural diamonds that had undergone a new process, developed by the General Electric Company (GE), that removes some or all of the color of a diamond. Distributed exclusively by Pegasus Overseas Limited (POL), an Antwerp-based subsidiary of Lazare Kaplan International (LKI), the diamonds are referred to as GE POL or Pegasus diamonds in the trade. These GE-processed diamonds look like untreated diamonds; however, careful examination has revealed that some of them exhibit subtle features that usually are not present in natural-color diamonds. This article presents demographic information on 858 (of the 960) GE-processed diamonds that had been incorporated into the GIA Gem Trade Laboratory database as of July 15, 1999, and describes some of the unusual internal features that were seen. As recently stated by GE, the procedure used involves high pressure and high temperature and, to date, is effective only on certain high-purity and high-clarity diamonds