Suncrest: Utah’s Diamond Treater

For the past two days, I’ve been in beautiful, mountain-studded Orem, Utah, visiting Suncrest Diamonds, which treats diamonds for the trade with HPHT (high pressure, high temperature). 

HPHT subjects low nitrogen brown type IIa stones to enormous amounts of pressure and heat (as high as 2,600 degrees Celcius), which replicates the forces that produce diamonds in nature.

After 15 minutes in the press, the color can improve dramatically. The ugly duckling browns are transformed into H-color and higher swans—although if they have a little nitrogen, they can become yellow, green, or orange. 

Here is one stone before:

And some after:


Suncrest (formerly Sundance) is a fascinating company. It is a division of U.S. Synthetic, a major manufacturer of industrial diamonds whose main competitor is De Beers–owned Element Six. According to division general manager Sonny Pope, sometime in 1999, when the news broke that Lazare Kaplan was venturing into HPHT, a dealer approached U.S. Synthetic and asked if it could “whiten” his brown type IIa diamond with one of its machines. It could, and a business was born.

Suncrest is a small operation, with only seven full-time employees. It treats about 15,000 carats of stones a year for the trade as a service; most of these stones are in the 1 to 6 ct. range, though the biggest stone it ever treated was over 100 cts. The company’s only public competitor remains Lazare Kaplan, which sells its processed stones under the brand name Bellataire, though there are reports of HPHT machines in Russia and China. Another company, NovaDiamond, for a while produced treated green stones, but is no longer active. (NovaDiamond also hailed from Utah, as that was the home of the inventor of synthetic diamonds, GE scientist Tracy Hall; Pope’s grandfather was once business partners with Hall.)

One of the reasons that HPHT remains a small business is because only Type IIa diamonds can be whitened. Type IIa diamonds are rare—comprising only about 1 or 2 percent of all the diamonds in the world. Still, Sundance’s clients are expert in sniffing out these stones, and the mining companies realize that. “They can charge premiums for them, because there is hot demand from the little niche that is always looking for them,” says Pope. “So [our customers] pay top dollar, and pray they will get an H or higher.”

And that is only part of the HPHT gamble. Low-clarity stones (VS or lower) sometimes break in the press, in which case costs are incurred by the submitter. Pope says that only happens to 1 in a 1,000 stones—yet it happens. “Every time we put a diamond in the machine, there is a risk,” he admits.

Here is one stone that didn’t make it.

HPHT is a permanent and irreversible treatment, but the FTC Guides say it must be disclosed. Suncrest requires all its clients sign an agreement committing to disclosure, and would cut off any customer found not mentioning the process during a sale. However, the GIA recently announced it had seen a growing number of large HPHT diamonds at its labs, which were submitted without notification ahead of time. Pope says at least one of the stones in question—a 28 carater—was sent in by Suncrest. “I thought they would know if it came from us, it is treated,” Pope says. From now on, it will be clearer.

Here is a GIA report for an HPHT-treated stone:

Even without disclosure, GIA has said it can detect “virtually all” HPHT gems. And while that is not the same as being able to detect all those stones, Pope doesn’t think identification is a huge problem. “The colored diamonds are especially easy,” he says. “There are always people who say they have seen diamonds get through [a lab undetected], but as far as I know that is just a rumor.”

While Suncrest mainly offers processing as a service, the company also has a new venture—which is why it wanted to talk to JCK. Certain type IIas can be transformed into pinks through a mixture of HPHT and irradiation. And so Sundance is now developing a line of pink stones; it already has an inventory of 300 pinks, which it will exhibit at the next JCK Las Vegas show.  “We are just finding our way around with that business,” Pope says. “We think they are a good product, but for now people are still kind of scared of them.”

One business Suncrest is scared of: Growing synthetic gem-quality diamonds—even though this can be done with HPHT machines, and the company often treats lab-grown stones.  “It’s very hard to make that profitable, until the technology changes,” says Pope.

Here is a company video with animation detailing how the process works:

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JCK News Director

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