Feature Gems & Gemology, Winter 1987, Vol. 23, No. 4

The Gemological Properties of the De Beers Gem-Quality Synthetic Diamonds

Gem-quality synthetic diamond crystals weighing up to 11 ct have been grown in limited numbers at the De Beers Diamond Research Laboratory since the 1970s. These crystals have been produced strictly on an experimental basis and are not commercially available. Examination of a group of 14 brownish yellow, yellow, and greenish yellow synthetic diamonds reveals distinctive gemological properties: uneven color distribution, geometric graining patterns, metallic inclusions, and, in most cases, fluorescence to shortwave but not to long-wave UV radiation.