Feature Gems & Gemology, Winter 2004, Volume 40, No. 4

An Updated Chart on the Characteristics of HPHT-Grown Synthetic Diamonds

A new chart, supplementing the one published in the Winter 1995 issue of Gems & Gemology, summarizes the features of both as-grown (“non-modified”) and treated (“modified”) synthetic diamonds currently in the gem market (that is, those grown by the high pressure/high  temperature technique). It includes photographs of visual features, information about visible-range absorption spectra, and illustrations of growth-structure patterns as revealed by ultraviolet fluorescence imaging. The chart is designed to help gemologists recognize the greater variety of laboratory-created diamonds that might be encountered today.