Feature Gems & Gemology, Fall 1988, Vol. 24, No. 3

Detection of Treatment in Two Unusual Green Diamonds

A pair of sharp absorption bands in the near-infrared region, referred to as H1b and H1c, have been detected in one (and the H1b band in the other) of two green diamonds known to have been treated. Until now these bands have been associated with the annealing of yellow to brown laboratory-irradiated diamonds. This is the first reported observation of these bands in green treated diamonds. Although these two diamonds may represent a special case, in that they are believed to have been irradiated, annealed, and then re-irradiated, the presence of one or both of these bands in a green diamond is one of the few reliable characteristics that identify that the stone has been treated in a laboratory.