New York: The Gemological Institute of America (GIA) has said that it suspects 500 colorless to near colorless diamonds submitted primarily to its laboratory in Ramat Gan, Israel have potentially been subjected to an undisclosed temporary treatment.

So far, the diamonds treated in this way have been submitted by just a few clients. The lab said the treatment is a process that temporarily masks the inherent color of the diamond and can lead to a higher grade, with the color difference being as much as three grades.

While the GIA has not yet identified the treatment process, it said it is being actively researched. The lab said it has terminated submissions from the clients who have submitted these diamonds to GIA and has notified the appropriate trade bodies.

The report numbers of the potentially treated stones can be seen here. The GIA asks anyone who has purchased or holds these diamonds to re-submit them to any GIA location for a free, expedited review.