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News & Highlight


  • A new type of CVD diamond observed in short wave ultraviolet (SW-UV). (Courtesy of IGI)
  • Diamond seed on pedestal in depressurized chamber / microscopic diamond crystals. (Courtesy of IGI)
  • Typical CVD striation as seen under short wave ultraviolet rays. (Courtesy of IGI)

An update on production & identification of CVD synthetic diamonds

Developments in the production and identification of synthetic diamonds have intensified significantly in recent years. The global gem and jewellery industry is closely monitoring how the diamond trade will approach disclosure and transparency in order to safeguard the sustainable growth in sales of both natural and synthetic diamonds, and most importantly, consumer confidence.

It is reported that De Beers, Gemological Institute of America (GIA), International Gemological Institute (IGI), and HRD Antwerp, among others, are already well equipped to detect large volumes of small diamonds. Hong Kong Jewellery has interviewed senior executives of major gemmological laboratories and trade bodies for an update on current developments.


Production & quality

Over the past decades, synthetic diamonds have been produced in increasingly better qualities. Wuyi Wang, director of research and development at GIA said: “There are a number of different manufacturers who produce a range of sizes, colours and qualities. The vast majority of the production is geared towards high-technology or industrial applications, while its use in jewellery remains rather limited.”

Since 2012, CVD (chemical vapour deposition) synthesis methods have been garnering increased attention. This production method works at moderate temperatures and low pressure so is less costly and less technically challenging than HPHT (high-pressure high-temperature). GIA published a research paper in 2012 (by Eaton-Magaña S and D’Haenens-Johansson) which reported that CVD synthetics can be grown faster and “without colour”, when compared to earlier techniques which tended to result in brown coloured stones, because the seed material included tiny particles of non-diamondiferous carbon.

“Colourless and near-colourless CVD synthetic diamonds are usually type Ⅱa,” said Wang. “Generally CVD synthetics are of very high clarity. However, recently one producer introduced tiny inclusions into the manufacturing process in order to make the stones appear closer to natural diamonds. In terms of colour, CVD synthetics are generally G-H colour, with some low as K.”

Gemesis Diamond Corp, headquartered in the United States, is one of the largest synthetic diamond producers in the world, and has managed to create and sell synthetic diamonds in a transparent and commercially viable distribution channel.

Gemesis commercially launched colourless diamonds and fancy-coloured diamonds in March 2012 and sells them online through selected distributors. The synthetic polished diamonds sold online range from 30 points to 1.60 carats for white stones, and from 20 points to 2 carats for fancy colours. According to Gemesis, every single one of its lab-created diamonds is sold accompanied by a grading certificate from IGI.

Currently, Gemesis has cutting and polishing operations in India and China. According to Stephen Lux, Gemesis former CEO, the company markets all of its diamonds exclusively in the United States. “We are looking forward to open and frank discussions with the Indian government and the Gems & Jewellery Export Promotion Council (GJEPC) in the near future in order to explore the possibilities of growing our cutting and polishing activities in India.”



In March this year, GJEPC and the Indian Diamond Institute (IDI) held a seminar in Surat where many diamantaires expressed their concern that small synthetic diamonds were contaminating the natural pipeline.

Diamond Intelligence Briefs reported in August that the New York-based lab Analytical Gemology & Jewelry (AG&J) had alerted the diamond trade that it recently found synthetic diamonds being sold as natural, type IIa brown stones.

The lab reports that after a client submitted a batch of these stones as natural HPHT-treated diamonds, the lab discovered 75 percent of the parcel was composed of diamonds that were grown by CVD process.

In October, Rapaport also issued a “trade alert” to the industry, warning that synthetic melee is now regularly being sold undisclosed and mixed with natural diamonds in parcels.

John Pollard, the US gemmological consultant and speaker from Pollard Professional Services in Texas said: “There is no doubt that synthetic diamonds will continue to occupy a growing segment of the market. Meanwhile, disclosure and transparency are keys to the continued growth of the diamond market.”

Vice-chairman of GJEPC, Pankaj Parekh, announced that non-disclosure especially in the wholesale sector and in small sizes, is a major problem facing the industry. Once the diamonds are set in jewellery, they become more difficult to test whether they are natural or synthetic. However, a broad awareness should be spread among the traders on the effects and ramifications of non-disclosure.

 The regional chairman of GJEPC, Chandrakant Sanghavi further added: "The problem is not on the manufacturing side, but on the trading side. However, it is important that the trade should follow the 3Ds, that is, disclosure, differentiation and detection. Parcels of small diamonds are vulnerable to being contaminated by synthetic diamonds, and there currently exists no mechanism to reliably and economically check large parcels of small stones. It is entirely conceivable that synthetic stones could reach the end consumers."

The World Federation of Diamond Bourse (WFDB) informed all its members that the diamonds invoiced and on the memo are natural diamonds and not synthetic unless otherwise stated in writing.

GIA notes that synthetic diamonds are an entirely legal new category of product. However, failure to disclose the fact that diamonds are synthetic is a violation of trading laws in most countries, as this would constitute deception or misrepresentation.

Furthermore, the US Federal Trade Commission (FTC), the World Jewellery Federation (CIBJO) and WFDB specifically require traders of synthetic diamonds to prominently disclose the fact that the products they sell are man-made.


Detection capability

Nowadays, stones above 20 points are usually accompanied by grading reports. The retailers are increasingly requesting certification of smaller goods as well, starting already at 10 points. Anything smaller would require parcel assessments, because per-stone certification would become too costly otherwise.

The issue lies mainly with smaller goods. Synthetics can be grown and polished to very small sizes, and mixed with natural diamonds of similar sizes and qualities.

In terms of identification, specialized devices such as DiamondSure, DiamondView and DiamondPlus are used to screen and examine stones that may be synthetic. IGI worldwide co-CEO Marc Brauner told Hong Kong Jewellery: “We have established a new way to screen parcels of melees faster than before.”

“In order to distinguish synthetics from natural stones, we follow a meticulous number of procedures and processes for each stone. From visual observation to testing with relevant equipment, we distinguish the diamonds between naturally mined type-II, naturally mined type-II treated by HPHT in order to change the colour, and man-made type-II, aka CVD synthetic including treated or not treated by HPHT,” he added.

He also suggested that besides having goods checked in the lab, buyers should be alert for too attractively-priced diamonds, and ensure that they purchase from established suppliers known to be reliable.

IGI uses FTIR spectroscopy analysis, photoluminescence spectroscopy analysis, phosphorescence spectroscopy analysis, detailed gemmological observations and more for further analysis and identification.



Disclosure of synthetics is an issue for concern. The challenge for the industry is to safeguard consumer confidence through ethical and transparent marketing. GIA and IGI both noted that as long as CVD diamonds’ origin is disclosed and consumers are informed, the market will determine what role synthetics will play. Gemological laboratories must keep up their efforts in research, identification, and innovation, and industry players should continue raising awareness for gemmological testing.

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