This content was first published on IGR – Italian Gemological Review no. 11 in 2021. The information provided here is therefore current as of the original publication date.
The International Gemological Institute (IGI) has announced that new details highlighting the manufacturing process of lab-grown diamonds are now added to its reports, effective January 2021. While previous reports always indicated that lab-grown diamonds “may include post-growth treatments to alter color”, the Institute will start stating if a synthetic diamond is “as grown” or may have been treated.
For untreated Chemical Vapor Deposition (CVD) and High Pressure High Temperature (HPHT) diamonds, the new reports will outline the individual growth process and indicate specifically that the stones are “as grown with no indication of post-growth treatment”. For the other CVD-created diamonds, the reports will note that they “may include post-growth treatment”.
CVD-produced diamonds result often in an unsatisfactory brown color due to impurities in the gas which is the source of Carbon and the relatively high growth rate. So a high-pressure, high-temperature (HPHT) treatment is very often required to improve the color of the CVD synthetic diamonds after their growth.
IGI Customers will also have the opportunity to request specific diamond types, including type IIa for CVD diamonds and type II for HPHT diamonds. Further, the Institute is working to incorporate additional commentary for post-growth treatment of fancy color diamonds in the near future.
Gem News published on IGR – Italian Gemological Review #11, Winter 2020-21
