GIA issues new grading policy for HPHT and artificially irradiated diamonds

The Gemological Institute of America’s (GIA) Gem Trade Laboratory has issued a new grading policy, effective immediately, for diamonds that have been processed by high pressure and high temperature (HPHT) or have been irradiated artificially.

“Because both HPHT annealing and artificial irradiation produce results that are stable in normal conditions of wear and care, we feel it is appropriate to issue GIA Grading Reports on diamonds that have undergone these processes,” said Thomas C. Yonelunas, GIA Gem Trade Laboratory CEO. “This policy . addresses the critical need for the disclosure of such processes, and provides a comprehensive analysis of the diamond’s quality.”

When one of these processes is detected, the GIA Grading Report will prominently disclose its presence. This disclosure will include, as applicable, an “Origin” field in the Color section that will state either “HPHT Annealed” or “Artificially Irradiated,” as well as an asterisk next to the Color grade to denote that there is a disclosure statement in the Comments section regarding the presence of one of these processes, GIA officials said in a statement. Before GIA will issue such a grading report, the diamond must be laser inscribed with (1) “HPHT PROCESSED,” (2) “IRRADIATED,” or (3) a specific registered name exclusive to diamonds that have undergone one of these processes (with “GIA” and the diamond’s unique report number).

“GIA feels that such an inscription is critical to ensuring that the presence of the process is adequately disclosed as the diamond moves through the marketplace,” Yonelunas said.

“Since Lazare Kaplan International subsidiary Pegasus Overseas Ltd. (POL) and General Electric Company (GE) introduced the GE POL (now BellataireTM) processed diamonds, GIA has devoted a great deal of its research efforts to developing practical criteria for identifying HPHT annealing,” said Thomas Moses, GIA Gem Trade Laboratory vice president. “GIA has examined more than 3,500 GE-processed diamonds to date, and has benefited from research performed by other esteemed organizations. As a result, GIA researchers have been able to isolate several gemological and spectral features that are effective in identifying HPHT-processed diamonds. These efforts are complemented by GIA’s decades of research and experience in detecting artificially irradiated diamonds.”

GIA has developed a series of procedures to identify GIA D-to-Z color (colorless to light yellow), as well as fancy color, diamonds that have been subjected to HPHT annealing. These have become routine steps in GIA’s diamond-grading process, just as the methods to test for artificially irradiated diamonds are well established. For further information on HPHT-processed diamonds, see the Fall 1999 and Spring, Summer, and Fall 2000 issues of Gems & Gemology. Or visit the G&G Web site at

For information about GIA Gem Trade Laboratory services, visit GIA’s Web site at, or call Client Services in New York at 212-221-5858, or in California at 760-603-4500.