Professional Jeweler Archive: The Changing Nature of Diamonds

April 2000


The Changing Nature of Diamonds

Tampering with a diamond’s natural constitution will continue in the new millennium

High-temperature/high-pressure techniques to alter color in diamonds stole the spotlight last year when scientists confirmed they can change color without the traditional use of irradiation. Most future announcements about diamond technology also will have the letters HTHP attached, experts predict. Gemologists emphasize we’ve seen only the beginning of diamond synthesis and enhancement, so a few other surprises may be in store.

The use of HTHP to improve diamond color grades had been rumored for almost a decade. In fact, at a World Federation of Diamond Bourses meeting in Russia last year, De Beers acknowledged the types of diamonds most likely to benefit from this technology had been held back from the market for years. This suggests at least a theoretical knowledge of the technology and its use in changing diamond color.

“Technology won’t go away – nor should it,” Maurice Tempelsman of Lazare Kaplan International said at the Gemological Institute of America’s International Gemological Symposium last year. “It cannot be stopped, nor must it be lamented. Our job is to present the facts, accept technology and turn it into an added benefit for consumers.”

Dealers and jewelers should anticipate future developments. As unscrupulous players get into the act of enhancing diamonds – inevitable given the high stakes – the chance for fraud increases, so a knowledge of the processes becomes necessary. Here’s a glimpse of what we may see in the years ahead.

Improving the Color Grade

We know relatively rare Type IIa diamonds are used in the GE/POL process to improve the color grade (GE/POL diamonds are distributed by POL, a subsidiary of LKI. The treatment was developed by General Electric). Some observers say a way may be found to improve the color grade in Type I diamonds also. This would vastly increase the percentage of diamonds that could be enhanced.

“There’s an old theory that you can do almost anything [regarding color] to any diamond,” says Alex Grizenko of Ultimate Created Diamonds, Golden, CO. “However, as far as I know, the improvement of Type I may be only speculative at this time.”

GIA’s Tom Moses agrees and sees the notion as far-fetched. “The presence of nitrogen in Type I stones will always be the obstacle unless a way is found to remove the nitrogen,” he says. “From what we now know, Type I diamonds could not be improved the two to three color grades that a Type IIa can.”

Improving the Color

Labs around the world are working to enhance natural diamonds in a way that produces natural-looking color. “We will see a lot more activity in taking brownish diamonds and making them a more attractive pure yellow,” says Moses. “Other efforts may involve reducing the tell-tale blue fluorescence seen in many HTHP stones.” Removing fluorescence would make identifying HTHP treated diamonds more complicated.

The primary focus now is to more closely duplicate in a laboratory the forces that cause color in natural diamonds, says C.R. “Cap” Beesley, president of American Gemological Laboratories, New York City. “This means colors will be tweaked to produce more colorless and convincing yellow diamonds,” he says. Beesley confirms he has established several contacts with Russian diamond laboratories skilled in diamond technology. He agrees the pace has picked up to discover more about the reaction of different kinds of diamonds to temperature and pressure.

“Like geuda sapphires, brownish diamonds are becoming a dinosaur,” he says. “First, they were unwanted and now they’re practically unavailable because everyone is using them for treatment purposes.” Beesley says closer simulation of the natural causes of color will cause detection challenges in the future. But he offers hope. “I still maintain that if you tamper with the real thing, there will be tell-tale signs down the road,” he says.

Different Colors

We also can expect efforts to create other fancy colors from previously unwanted diamonds. Branko Deljanin of EGL Laboratories, New York City, says the challenge is to produce fancy pink and other colored diamonds from natural brownish rough. “Aside from working with the variables of temperature, pressure and time, scientists are looking at brownish diamonds from different localities to see whether they react differently to similar conditions,” he says. Beesley says variations on green, blue and pink diamonds and improved fancy yellows are likely this year or early next year.

Moses adds a word of caution. “The key is being able to predict consistent outcomes,” he says. “General Electric seems to have mastered this with GE/POL diamonds. But there is a much greater diversity of Type I diamonds, which suggests largely inconsistent color results. Still, we’ll probably see a greater proliferation of fancy colors. I also believe they’ll all be readily identifiable.”

Other Technology

What has not yet developed commercially in the jewelry industry is a use of chemical vapor deposition technology. CVD is a process of thin-film diamond synthesis that doesn’t involve HTHP. It’s a low-temperature/low-pressure process that deposits a thin layer of synthetic diamond on almost anything – including natural gemstones. CVD eventually may find its way to the jewelry industry. For now, CVD is used primarily for mechanical or thermal conductivity in machine building or electronics.

Moses says GIA has conducted experiments in this area and has found detection of an overgrowth is straightforward. Aside from what appears to be a granular structure of the CVD, there are notable differences along the interface between the subject and the overgrowth itself.

The advances in technology – from HTHP advances to diamond overgrowth – present modern challenges in diamond gemology. How the industry deals with the advancements will determine whether they become friends or foes.

– by Robert Weldon, G.G.

Laboratories around the world are focusing on ways to use high temperature/high pressure mechanisms to change colors in natural, mostly brownish Type I diamonds.

Copyright © 2001 by Bond Communications