arch 1, 1999 is a watershed date in the gem and jewelry trade. This is when General Electric (GE) and Lazare Kaplan International (LKI) unveiled their latest contribution to the diamond and jewelry industry: diamonds that had undergone a new GE process "designed to improve their color, brilliance, and brightness" (Rapnet, 1999). Colloquially, these diamonds became known as "GE POL" or "Pegasus" diamonds, because they were being marketed through LKI subsidiary Pegasus Overseas Ltd. (POL). At the July 2000 Jewelers of America trade show in New York, however, the brand name Bellataire was officially launched. The first gemological description of GE POL diamonds appeared in fall 1999, when GIA published an overview of the macroscopic and microscopic features observed in 858 GE POL diamonds they had examined up to August 1999 (Moses et al., 1999). Subsequent articles by the SSEF Swiss Gemmological Institute and De Beers provided more analytical details on GE POL diamonds and suggested spectroscopic methods of identification (Chalain et al., 1999, 2000; Fisher and Spits, 2000). The Gübelin Gem Lab (GGL) has had an ongoing cooperation with GE, LKI, and POCL (Pegasus Overseas Company Ltd.) to investigate the gemological and analytical characteristics of GE POL diamonds, in order to help develop identification criteria. Because of this collaboration, staff members at GGL were given the opportunity to document a selection of diamonds taken from current GE production, both prior and subsequent to high pressure/high temperature (HPHT) processing (figure 1). This study represents the first independent investigation of actual GE POL diamonds both before and after processing by General Electric. Such an investigation is crucial to understanding the mechanisms behind the color alteration and thus to providing greater insight into potential methods of identification. The present report not only addresses the alterations in color, inclusions, graining, and strain produced by the GE process, but it also considerably expands the

The phase compositions of undoped and europium-doped zirconia samples, obtained by precipitation and thermal treatment from 350" to lOOO"C, have been investigated by powder X-ray diffractometry, infrared spectroscopy, and cathodoluminescence spectroscopy. The low-temperature stabilization of tetragonal zirconia is mainly controlled by the presence of anion additives, such as ammonium chloride. The influence of the crystallite size is less important. Cathodoluminescence spectra show a structural similarity between tetragonal and amorphous zirconia.

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