Small synthetic rough stones have been discovered bearing the classic octahedral shape found in natural stones, which may lead to new detection issues for the rough market, according to Antwerp, Belgium–based lab HRD.
by Rob Bates.
In an announcement last week, the lab said it had received several batches of small diamonds produced by the HPHT method—in sizes from 0.01 ct. to 0.04 cts.—grown in the classic octahedral shape from Chinese producer Taidiam. So far, most HPHT-produced synthetic rough has grown in cubo-octahedral form, while rough produced with the CVD method bears a plate structure. Both have significant visual differences from the regular octahedral shape that was previously found only in natural stones.
“Up until now, it has been easy to tell the rough apart,” says Katrien De Corte, HRD’s chief education officer. “Now it may not be as straightforward.”
Once the diamonds have been polished, they are still detectable by the standard methods, she stresses.
All the stones are type IIas and type IIbs, so they can be separated out with a screening device. In addition, a lab with the standard detection devices can distinguish synthetic rough from natural. But until now, there hasn’t been a need for a screener or detection device for rough, just for polished.
There may be ways to visually differentiate the diamonds under a microscope, but that is something HRD is still exploring, De Corte adds. It hopes to have more information next week.
While growing synthetic rough stones that resemble naturals would seem a way to fool traders, Taidiam told HRD the classic octahedral shape produces better-quality stones.
But De Corte adds, “The stones are so small, it’s hard to tell.” (Taidiam could not be reached for comment.)
So far, there is no evidence that this octahedral synthetic rough has appeared on the market. But its appearance certainly raises alarm, De Corte says.
“The company has told me they are the farthest along in growing octahedral stones,” she says. “But now that they can do it, I’m sure others will try as well.”