Two Treated-Color Synthetic Red Diamonds Seen in the Trade

Two dark brownish red faceted stones, recently submitted to the GIA Gem Trade Laboratory for standard origin-of-color reports, were found to be treated synthetic diamonds. This conclusion was based on observations of: patterns of zoned color, U. V. luminescence, and graining; metallic inclusions; and certain bands in the visible-and infrared-range absorption spectra. We believe that this is one of the first published reports of treated-color synthetic diamonds seen as faceted gems. For some of the gemological features desen3ed here, such as visible-grange spectra with sharp absorption bands, this is one of the first reported occurrences in gemquality synthetic diamonds.