HPHT Is Here To Stay - Published in the November/December 2013 Issue of Retail Jeweler Magazine

A short history of the innovative process of the development of HPHT diamonds with answers to questions you may have or your customers may ask.

“I let the fire out. I took my cylinder and unscrewed it while it was still so hot that it punished my hands, and I scraped out the crumbling lava-like mass with a chisel, and hammered it into a powder upon an iron plate. And I found three big diamonds and five small ones,” excerpt from The Diamond Maker published in 1927 by H.G. Wells.



Twenty-six years later, in 1953 ASEA, SWEDEN’s major electrical manufacturing company produced synthetic diamond in Stockholm Sweden. Using a bulky apparatus designed by Baltzar von Platen, the discovery, however was kept secret.

The international race was on to discover a method to produce man-made diamond. General Electric had started research in the 1940’s but had shelved the project during World War II. The research was rekindled in earnest shortly after the war. GE scientists knew that if they were going to succeed in synthesizing diamond they needed to invent a new press to supplement their task. This led to the invention of the well- known “belt” press. Additional presses evolved from the tetrahedral, to the BARS, to the cubic press. The most complicated and the most expensive presses used today are the Cubic-type presses. These presses build up pressure of 70 Kbar per square inch, at a temperature of around 2500°C.


Dr. H. Tracy Hall, a researcher for General Elec- tric, achieved the first commercially successful synthesis of diamond on December 16, 1954.

“My hands began to tremble; my heart beat rapidly; my knees weakened and no longer gave support – I knew that diamonds had finally been made by man.” – Dr. H. Tracy Hall


GE made a fortune from this discovery; Tracy Hall received a 10 dollar US Savings Bond as his reward. This gave rise to an industrial man made diamond industry that for decades was represented by two main players, GE Super abrasives and De Beers Industrial Diamonds. In 1955, a year after his invention of manmade diamonds Dr. Hall founded Novatek.


In 1999 Novatek, a Provo UT manufacturer of industrial diamonds accidentally discovered that the HPHT process could change the color of diamonds. The company formed Nova Diamond Inc. to market the process.


However in 2001 Nova Diamond quit the HPHT gem business because of what the company’s leader, David Hall, characterized as the underhanded practices of dealers. The company refused to be party to this deception.


In 2003, Sundance Diamonds, now known as Suncrest Diamonds, a subsidiary of US Synthetic, began offering HPHT diamond enhancement to the trade. Currently Sun- crest is the largest HPHT diamond processor in the United States.

May 1999 “The Integrity of the industry is at stake”

On March 1, 1999 Pegasus Overseas Limited (POL), a new subsidiary of Lazare Kaplan International Inc. (LKI), announced “an exclusive agreement under which POL will market natural diamonds that have undergone a new GE process that enhances certain characteristics of select natural gemstone diamonds.” This shocking announcement caught GIA and the diamond industry by surprise, creating concern as to how this new process would affect the future of diamond commerce.

In a GIA press release Bill Boyajian, then president of GIA expressed his misgivings; “GIA has not been privy to the development of this alleged treatment and to date has received very little information from the parties involved. It is usual for GIA to be consulted well in advance by firms involved in gemstone treatments and I see this situation as no exception. Early consultation is a vital stage of the disclosure process. It enables GIA to fulfill their mission to inform and educate the industry about new developments and to protect the consumer. Due to such scant information, GIA has yet to discover any conclusive evidence to identify this treatment. The specific process is GE’s business; the ability to identify the treatment and ultimately to identify diamonds treated by the process is the diamond industry’s business. If diamonds are treated in any way, then the trade has a right to know- and ultimately so does the consumer. The Integrity of the industry is at stake.”


Growth of synthetic diamonds takes place in the following way: carbon is placed in a graphite capsule, a seed is inserted on which the diamond crystal will grow and a catalyst is added that enables the crystallization to form. It takes at least two days for 1ct rough to grow and multiple crystals can grow in one capsule. The necessary conditions for transforming graphite into diamond are 55Kbar and a temperature of 1400-1500°C. The HPHT process is also applied for color enhancement or color alteration of natural diamonds. Each diamond type will respond in a different manner to this process. Diamond type is the most significant factor in predetermining what color a diamond will become when exposed to HPHT.


Why some diamonds turn white, yellow, pink or green... Diamond type is a method of scientifically classifying diamonds by the level and type of their chemical impurities. Diamonds are separated into four types: Type Ia, Type Ib, Type IIa and Type IIb. The impurities measured are at the atomic level and so, unlike inclusions, they require an infrared spectrometer to detect.

Type I diamond has nitrogen (N) atoms as the main impurity, at a concentration of up to 1%. They do not affect the diamond’s color. About 98% of gem diamonds are type Ia: these diamonds belong to the Cape series, named after the diamond-rich region formerly known as Cape Province in South Africa, If the nitrogen atoms are dispersed throughout the crystal in isolated sites, they give the stone an intense yellow or occasionally brown tint. In nature, the rare canary diamonds belong to this type, which represents only ~0.1% of known natural diamonds. These nitrogen rich stones can be changed from brown to green and yellow. The ultimate color depends on the type and amount of nitrogen content and the temperature employed during the HPHT process. Rarely, low nitrogen type 1b brown diamonds can yield purplish pink.

Type II diamonds have very few if any nitrogen impurities. Pure type IIa diamond can yield “bubble gum pink” or white. These diamonds make up approximately 1.8% of gem diamond. Type IIb diamonds, the rarest of all, account for approximately 0.1% of gem diamonds. They are always electrically conductive and usually display steely blue or gray color in nature. Type IIb contain boron atoms scattered within the crystal matrix. Very rarely Type IIb can occur as browns stones, and it is then that HPHT can change them to blue color.

Detection of HPHT enhanced diamonds

1) All fancy colored diamonds should have verifiable certification from a major gem lab. Traditional gemological equipment is no longer adequate to identify natural diamonds from enhanced or man-made. Accurate distinctions must now be made using expensive high tech laboratory equipment.

2) Clean white diamonds should have a certification from a major gem lab or at the very least a written statement guaranteeing natural. This includes diamonds in both large and small sizes. Your dealer should stand by his product.

3) If you don’t know your diamonds then know your dealer and hope he knows his diamonds. Even the savviest dealers today are unable to keep track of what is and what is not natural. On a recent buying trip to India, I discovered a fair percentage of my half-carat and smaller diamonds were manmade. All stones were Type II, which is still the predominant type for synthetics. Since I am actively looking for Type II, mine is a particularly precarious endeavor.

Typically wholesale diamond buying is conducted through a buying office that in turn contacts a variety of brokers. I have requested that my Indian buying office keep track of the source of each and every purchase no matter how small. All our brokers have been informed that any synthetic or treated diamonds found in our purchases will be considered fraud and will be returned and/or reported to authorities. I suggest that retailers make the same requirements of their dealers

4) If you are buying uncertified diamonds from the public, invest in a shortwave UV transparency tester. Any stones that are transparent to SWUV are likely type II and need to be submitted to a major gem lab for further testing.

HPHTdiamonds.com and Beyond...

Sourcing, manufacturing, and selling HPHT diamonds has been my primary business for the last 10 years. Over the past decade I’ve seen the process of HPHT treatment and the general attitudes about the stones evolve. Originally I bought cut brown diamonds in India and rough stones in Brazil for processing in Russia. There was a lot of breakage initially although I painstakingly selected the cleanest stones. The colors we ended up with were mostly orangey yellow and yellowish green. Color saturation and tone were not very predictable. I recognized in short order that I had little control over this fledgling process. .

Always a staunch advocate of treatment disclosure, I was disappointed to find many dealers selling HPHT enhanced diamonds as natural. On one occasion I purchased several white stones from a dealer in Brazil who swore that the stones were fresh from his own mine, later to find that they had previously been HPHT processed in the USA and had traveled back to a small town in Brazil. These types of occurrences initially gave our fledgling business a bad name. Additionally I encountered many detractors of HPHT’s merits. Many retailers rejected the HPHT processed stones saying that they would never consider handling “treated diamonds”. I found this position amusing since they were conveniently ignoring the fact that nearly every colored stone in the store had been enhanced in one way or another.

But times change. I learned to become deft at using an FTIR, which gave me control over color. Suncrest Diamonds starting processing goods here in the US and became my mentors, helping me to understand the intricacies of HPHT processing. With more information regarding HPHT treatment and better laboratory identification methods, people started to appreciate the value and beauty of this new product. Ultimately it was the public seeking beautiful, value priced items that recognized the advantages of HPHT. They learned that they could buy more vivid yellows, cleaner whites, rare pinks and greens for a fraction of the cost of unheated diamonds. In turn, innovative retailers followed suit to service this new clientele.

Today, most major gem labs can detect HPHT enhancement and most stones are sold with certificates. As a result HPHT are entering the mainstream. The demand for HPHT enhanced diamonds around the world is increasing, as are sales here in America. The greatest problem confronting HPHT purveyors in the future will not be lack of sales, but the lack of good material as demand increases. History tells us that the introduction of every new gem product requires time to gain momentum. Heated ruby and sapphire, Tanzanite, oil and fracture filled emerald, irradiated tourmaline, blue topaz etc., all had rocky beginnings but became mainstays in nearly every jeweler’s arsenal. It appears that HPHT enhanced diamond has begun its uphill trek to gem industry respectability and acceptance. The newest kid on the block seems to have found his niche.