The first place many turn to if they have suspicions about a stone and the treatment it has undergone are the gemological laboratories. The Gemological Institute of America (GIA) has been researching and identifying HPHT treated diamonds and synthetic diamonds from the get go.

 

We asked them just how big the problem of non-disclosure of these diamonds are and how certain they are that all the stones are detectable.

 

 

Q: From GIA's experience, what types of stones are currently being HPHT'd (size-wise)?

A: We have not seen a clear trend in particular sizes. We are seeing a range of sizes, from melee in yellow colors to over twenty carats for diamonds in the colorless range. 

 

What percentage of all stones submitted to the GIA are suspected of undergoing the HPHT process? And, what percentage of suspect stones are 'flagged' (i.e. no conclusion can be drawn as to whether they are HPHT processed or not)?

(a)   While we cannot state a number, it is safe to say that only a very small number of all diamonds submitted to the GIA Gem Laboratory for grading are found to be HPHT-treated. At the same time, it is important to note that GIA has examined more than 15,000 HPHT diamonds and has compiled a large database of information not only on annealed diamonds, but on natural diamonds that are the types that are subjected to treatment.  These data are used to further our research.

(b)  All diamonds submitted to the GIA Gem Laboratory for grading are carefully screened for the presence of HPHT-annealing by highly trained Laboratory staff members using state-of-the art instrumentation. Multiple graders examine each diamond. During the screening process, certain indicators can occur that necessitate further testing. The Laboratory continues the testing until a conclusion is reached.  There has been an extremely small number of diamonds that we have concluded to be of undetermined origin of color. 

 

Have there been cases of a stone that was previously certified by GIA, returning to the lab and found to actually be one that has undergone HPHT?

This has occurred in only a very few isolated instances.

 

On the issue of synthetics, how easy is it to distinguish 'natural' diamonds from synthetics?

GIA has been characterizing and following the developments of synthetic diamonds since the first industrial quality diamonds were produced by GE in 1955.  In fact many of the identification features we noted in 1971 are still important today in the identification of synthetic diamonds grown by the high-pressure process.  Gems & Gemology has published a few articles in the last decade illustrating properties of synthetic diamonds that can be used by a jeweler or gemologist to identify many synthetic diamonds.  The GIA Gem Laboratory can conclusively identify all synthetic diamonds in our laboratory and most synthetics have characteristics that facilitate the identification process for trained jewelers and gemologists.  CVD synthetic diamond is more challenging to identify, but an article on Apollo CVD synthetics will be published this winter in Gems &Gemology, describing their properties.

 

Would most jewelers, without turning to a gem lab, be able to identify synthetics from natural diamonds?

Identification of synthetic diamonds requires gemological training and in some instances, specialized equipment. Many jewelers have this training. On the other hand, jewelers worldwide have increasingly adopted authentication reports, such as the GIA Diamond Grading Report, as part of their process for buying and selling diamonds. We likewise always advise consumers who are purchasing diamonds – one of the more substantial purchases most consumers will ever make – to obtain such authentication. By the same token, GIA issues a Gemological Identification Report for synthetic diamonds (as well as colored stones and pearls) to authenticate the material. Besides upgrading gemological skills and adding the proper gemological equipment, a report from a respected gemological laboratory is the safest and surest way to verify the authenticity and quality of diamonds.

 

How does the GIA grade synthetics? Are certificates issued? If so, what are the differences between certs for natural diamonds and for the man-made diamonds?

GIA does not issue a Diamond Grading Report on synthetic diamonds, but does issue a Gemological Identification Report. The major difference is that a Diamond Grading Report or Diamond Dossier will characterize natural diamonds based on the 4Cs (color, clarity, carat weight, and cut) of the International Diamond Grading System, while the Gemological Identification Report verifies the material is synthetic diamond, but does not provide an analysis based on the 4Cs.

 

Once a synthetic has been set in a jewelry piece, can it still be identified as such?

Yes, in most cases, it can still be clearly and conclusively identified (by a qualified person, using the appropriate equipment) as synthetic. Ideally, a diamond in question may need to be removed from its setting for proper examination.

 

What advice would the GIA give dealers and retailers who suspect that they have bought a stone that is either synthetic or HPHT?

The diamond should be submitted to the GIA Gem Laboratory (or other respected gemological laboratory) for analysis.

 

What measures would the GIA like the industry organizations to take to safeguard again HPHT or synthetic diamonds from being traded on the market without disclosure?

First, increased awareness and training should be emphasized. GIA has published extensively on both synthetic diamonds and HPHT-treated diamonds. Gems & Gemology, The Loupe, GIA Insider, and GIA’s Web site contain many articles that can help professionals throughout the industry improve their knowledge. In addition, the Richard T. Liddicoat Gemological Library and Information Center has numerous references on these topics. And GIA Education offers a number of courses, from Diamond Essentials, to Diamonds and Diamond Grading, to Advanced Gemology and Gem Identification, which can greatly upgrade crucial professional knowledge. In addition, industry professionals should agree on the abiding principal of full disclosure of all treatments and adherence to appropriate enforcement measures for the protection of the industry as well as the public trust.