HPHT Heats Up

Last November, JCK first reported that gem labs were noticing increasing numbers of undisclosed high-pressure/high-temperature-treated (HPHT) diamonds on the market, both near-colorless and fancy-colored. (See "The Heat—and Pressure—Is On," JCK, November 2001, p. 102.) Now the number is growing, and so are concerns. "The volumes we are seeing are not huge, but it's definitely a concern," says William E. Boyajian, president of the Gemological Institute of America (GIA). "More people are doing it, and they are probably varying the recipes a bit. It's posing more challenges." New York's European Gemological Laboratory, which is turning HPHT research and grading into something of a niche, sees about 300 treated stones a month, and 30% of them are undisclosed, says research manager Branko Deljanin. The lab knows of at least 10 companies producing the stones—in Russia, Asia, and even

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