The synthetic diamond problem for fancy colour diamonds – Part I



Posted November 18, 2021 | By Dr. Thomas Hainschwang


Synthetic diamonds are still a hot topic debated across the industry and the media. How did they become so prominent, and what caused the sudden rise of synthetic diamonds? DR THOMAS HAINSCHWANG explores. 

Man-made diamonds have a long history; the first single crystals (HPHT process) were produced in 1953 by ASEA in Sweden, the first polycrystalline stones (CVD process) in 1952 by the Union Carbide Corporation, USA.

The two processes are as follows: one method, known as HPHT synthesis, sees diamonds ‘grown’ from graphite under high pressure and high temperature (HPHT) conditions (1,300–1,800°C) in a special HPHT press; while CVD synthesis sees diamonds ‘grown’ from a gas phase – typically CH4 (methane) – under vacuum and distinctly lower temperatures (700–1,000°C).

Keeping in mind that both processes are well established, what was it that made the existence of synthetic diamonds a problem in the jewellery and gemstone industry only in recent years?

Was it due to the misrepresentation of such synthetics, and why did it take until 2015 for synthetic diamonds to gain some traction and recognition? Let’s investigate what caused the change in synthetic diamond standings.

Three modified chinese cubic HPHT presses used for the production of synthetic diamond.

Although gem quality synthetic diamonds have been around since the 1970s, they have only been commercially available since the late 1980s.

Yellow and blue HPHT synthetic diamonds were available at prices well below those of equal colour natural (untreated) diamonds, whereas near-colourless-to-colourless synthetic diamonds were more expensive than natural diamonds. The price difference was because the production of colourless synthetic diamond was difficult, with most material turning yellowish and included.

Until 2003 all gem-quality synthetic diamonds were manufactured by the HPHT process, after which the company Apollo Diamonds USA announced the successful growth of single crystal gem-quality synthetic diamonds by the CVD process.

Since this process was announced as revolutionary, in that it could produce colourless instead of colour material, the year 2003 represents the beginning of the rise of synthetic diamonds, even though it took yet another nine years before CVD synthetics actually became commercially available..

In 2010, Gemesis – a company that produced and commercialised colour HPHT synthetic diamonds until then – started to manufacture CVD synthetic diamonds on a larger scale. Therefore, only from 2012 were CVD diamonds actually commercially available through Gemesis, and on a smaller scale through other companies such as Scio (who had acquired Apollo Diamonds), Orion and Soni. However; the overall production was still dwarfed when compared with natural diamonds.

Two typical colored HPHT synthetic diamonds as they are available commercially since the late 1980’s. The sample on the left is a high temperature annealed yellow synthetic diamond and the sample on the right is an as-grown type IIb synthetic blue diamond. Image: Dr. Thomas Hainschwang.

 

Meanwhile, the HPHT process remained unable to produce colourless diamonds at prices lower than natural diamonds; besides experimental diamonds mostly produced in Ukraine, there was only one company – AOTC – attempting to commercialise colourless HPHT synthetic diamonds. The author acquired such a diamond in 2014, and which was 15 per cent more expensive than an equal quality natural diamond.

Now since the colour diamond market share in volume is miniscule compared to the volume represented by colourless (“white”) diamonds, synthetic diamonds – even though available for decades in yellow and blue shades at prices well below natural diamonds – could not develop a significant market share.

It needed momentum, and was triggered by progress that occurred between 2013 and 2014, when the Russian company New Diamond Technology first produced large, perfectly colourless and clean HPHT synthetic diamonds. Dr. Andrei Katrusha was the lead scientist responsible for the synthesis, he is likely still the most successful manufacturer of large to very large HPHT synthetic diamonds.

New Diamond Technology achieved this because of a newly designed, so-called, ‘cubic HPHT presses’ from China, in combination with improved technology. Following this, synthetic diamonds started to become a real and recognisable problem for the natural diamond market.

Today there are numerous manufacturers of synthetic diamonds targeting the global gem market, producing large quantities of CVD and HPHT synthetic diamonds at significantly lower prices than comparable natural diamonds. Most production facilities are in China and India.
 

A 25-carat HPHT synthetic blue diamond crystal, grown by Andrei Katrusha at NDT in 2015/16. Image: Dr. Thomas Hainschwang.

 

While larger single diamonds are a minor problem for the natural diamond market –  these stones are generally certified and easily identified with appropriate testing equipment – pollution of melee diamond with synthetics became a major and recognised problem in 2015.

With everybody focused, and continuing to focus on, colourless melee diamonds, the problem today is particularly significant for melee-sized colour diamonds because, since 2010, practically all parcels of yellow melee diamonds tested by the author contained HPHT synthetic diamonds. In addition, since 2019 most parcels of brown melee diamonds contained CVD synthetic diamonds, and since 2020 grey and salt and pepper (included) diamonds often contain HPHT and CVD diamonds.

Interestingly, many dealers of colour melee diamonds, and even some very prominent jewellers using large quantities of fancy colour melee diamonds disregard these facts, claiming that “they know their supplier”.’

This is a risky claim, as guaranteed clean colour melee diamond parcels virtually don’t exist in the current market unless 100 per cent of the stones have been tested by a reputable gem testing laboratory.

 

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www.ncdia.com

The Natural Color Diamond Association provides transparent, up-to-date scientific and trade information in order to facilitate fair trading, confidence, and consumer education in the natural colour diamond market.

The organisation aims to keep members informed of scientific data which may affect values and availability, as well as provide strategies to create enthusiasm for this unique category of precious stones.

Our goal is to enhance the experience of anyone buying or selling a natural colour diamond.

 





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