The market is seeing a spate of green diamonds coming back from grading labs as treated, Thomas Hainschwang, cofounder of GGTL Laboratories, told the Rapaport Diamond Podcast.
“Quite a [lot] of stones that have been certified as natural [color] in the not-too-far-away past have been recertified by the same lab in recent years and came back as not natural anymore,” the expert in colored diamonds said. “They basically changed from a natural [color] origin to ‘undetermined’ or even treated, which has created quite a bit of unhappiness in the market.”
It’s unclear why these statuses are changing, said Hainschwang, who declined to name the lab in question. The Gemological Institute of America (GIA), which has a leading position in this segment, declined to comment to Rapaport News.
Green diamonds thought to have natural color can become “immediately worthless” if something like this happens, according to Hainschwang, whose GGTL network has branches in Geneva, Liechtenstein and Antwerp.
“If you have a 3-carat vivid-green-blue, that would go for probably nearly $3 million,” he continued. “If you get ‘treated’ for that, you can sell it for 3,000 bucks, maybe 5,000 bucks.”
In conversation with Rapaport News Editor Joshua Freedman, Hainschwang also spoke about the latest issues in grading, his views on synthetic diamonds, and whether you can use technology to identify the origin of a stone.
Listen to the full podcast here: