Near-colorless HPHT synthetic diamonds from AOTC Group

Abstract

The gemological and spectroscopic properties of 52 colorless to fancy light-colored HPHT synthetic diamonds (40 of them colorless or near-colorless) produced by AOTC using either toroid- or BARS-press technologies were characterized. In addition to achieving excellent color grades, these commercially available faceted synthetics had a weight range of 0.05 to 0.80 ct, and possessed IF to I2 clarity. Their synthetic origin may be difficult to determine with standard gemological techniques alone, but they were conclusively identified using advanced testing methods, including photoluminescence, FTIR spectroscopy, and fluorescence imaging. Inclusions in two samples, grown by different press types, were studied using LA-ICP-MS. The trace-elemental analysis results indicated that the inclusions formed by the trapping of the solvent/catalyst melt during synthesis. Analysis of the combined multi-technique data provided insight into the identities of the solvents, catalysts, and nitrogen getters possibly used to grow high-quality HPHT synthetic diamonds. © 2014 Gemological Institute of America.