corundum, synthetic corundum.7, flux, Chatham, gems

Gunawardene examines the gemological characteristics of Chatham flux-grown synthetic blue and orange sapphires, emphasizing the increasing difficulty of separating such products from natural corundum. Microscopic examination is presented as the most reliable means of identification. Diagnostic internal features include remnants of the flux melt and platinum inclusions, while growth structures may closely resemble those found in natural sapphire, although subtle differences can aid identification. The paper illustrates these features with eight figures, six in color, and discusses their usefulness in distinguishing Chatham synthetic sapphires from natural stones.