The American Gem Society Laboratories is implementing a new policy regarding disclosure of HPHT (high-pressure, high-temperature) treatments performed on diamonds submitted to AGSL for grading.

Disclosed Policy—For a type IaB or IIa diamond that the client says has been HPHT treated, the following will appear on the AGSL Report: “The client has disclosed that this diamond has been high-pressure, high-temperature processed to improve its appearance.”

Non-Disclosed Policy—In cases where a type IaB or IIa diamond shows no indication of treatment, the following will appear on the AGSL Report: “Short UV transparent diamond (type IaB or type IIa)—No indications of high-pressure, high-temperature treatment.” If the AGSL cannot determine if a diamond has been treated, the following will appear on the AGSL Report: “Short UV transparent diamond (type IaB or type IIa) —High-pressure, high-temperature treatment is undeterminable.” Diamonds that appear to have been HPHT-treated will be returned to the client ungraded, and the lab will bill the client for a consultation fee.