Observations on HPHT-Grown Synthetic Diamonds: A Review

sure, high-temperature (HPHT) process have been commercially available since the mid1990s. This article presents statistical information and distinctive identification features based on a review of data gathered by GIA, principally at the New York and Carlsbad laboratories, for several thousand HPHT-grown synthetic diamonds. This study includes all HPHT synthetic diamonds submitted to GIA between 2007 (the year GIA started issuing Synthetic Diamond Grading Reports) and 2016. No summary has been published on such a large number of HPHT synthetic samples. We describe here the diagnostic means of identification, with an emphasis on the goods currently being sold for jewelry use. Box A details some of the most important identification criteria that may be used by gemologists. Of this sample set, 12% were colorless to nearcolorless (D–J), 12% blue, 13% yellow, 4% pink to red, and 54% yellowish orange to orangy yellow (e.g., figure 1). The remaining 5% showed other colors, including green-yellow and brown-orange. This set represents both as-grown and treated colors. While some samples were purchased by GIA on the market or from manufacturers, or were loaned or donated to us by manufacturers for study purposes, most were sub-