AG&J, a NY based gemmological lab, discovered a parcel containing several undisclosed synthetic diamonds. [More Information]
Growing diamonds using Chemical Vapour Deposition (CVD) has been making the news lately for being able to produce clean, white diamonds up to 1 carat and slightly above. The CVD process is less expensive than growing diamonds in HPHT presses. However many of the CVD diamonds come out brown or grey and must be treated by HPHT to achieve near-colourless grades. By skipping the secondary HPHT process, a brown CVD diamond can be produced at a low enough cost to enter the already inexpensive market for brown melee diamonds. And brown diamonds are currently the rage in designer jewellery so there is a strong demand.
If these stones were entering the market with full disclosure, they could be a very viable product. They are attractive, conflict-free and affordable. But unfortunately they are showing up undisclosed and mixed with natural diamonds in wholesale parcels.<
Retailers must always protect their reputations. In the past we could always count on well-known and trusted dealers but as the article mentioned, the stones were purchased in the open market in Mumbai from a trusted dealer. So far, all cases of undisclosed synthetic or HPHT treated diamonds have come from the open markets and not through sight-holder supply chains. But that could change at any time.
The detection of synthetic and treated diamonds is difficult and requires advanced testing equipment. Most good gemmological labs can separate natural, treated and synthetics. Prices for this type of screening are running between $.50 and $1.00 per stone, depending on quantity. I would expect the prices to get lower in the future as both demand and technology advances. This is great for a small production shop but can get very expensive for high volume manufacturers.
So what is a retailer to do?
Unfortunately, there is there are no tools available to the typical retailer for identifying HPHT or CVD diamonds. This includes detecting HPHT colour treatments. Maybe someday, probably soon…but not now.
However, we can identify suspicious stones quickly and easily. All synthetic diamonds, both CVD and HPHT are Type IIa. Type IIa diamonds are transparent to short-wave ultraviolet (SW-UV) light and we do have simple tools available to identify and pre-screen these diamonds. The SSEF Diamond Spotter works well and is inexpensive. The HRD D-screen is expensive but gives you an LED reading. There are several other companies working on similar tools, or you can even make your own. Just always be sure to wear protective goggles when viewing SW-UV because it can damage your eyes.
If the stone is transparent to SW-UV, send it to the lab. If a diamond is not transparent to SW-UV then you know it is natural. This will save you a lot of money in lab fees since you will only submit suspicious stones.
This is only the beginning. There will be a lot more lab and treated stones sneaking into the market. If you keep up to date on new gemmological technologies and stay educated; there is nothing to fear. Just stay vigilant and aware.