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Natural selection: An article by Rapaport on diamond-verification services for undisclosed lab-grown and treated stones

With the rise of undisclosed lab-grown and treated stones, jewelers are turning to diamond-verification services to avoid misleading their customers.


lab-grown diamonds

Image: Cayen Collection

When consumers buy natural diamonds, they’re trusting the seller to offer them an authentic product that comes from the earth. That trust is threatened, however, when somewhere along the diamond pipeline, a supplier or jeweler fails to disclose laboratory-grown stones, treated diamonds, or diamond simulants.

“Contamination of the natural-diamond supply chain has triggered business headaches for many designers, manufacturers, retailers and customers,” says Soraya Cayen, owner of luxury jewelry salon Cayen Collection in Carmel, California. Her boutique carries natural-diamond jewelry by notable designers such as David Webb, Fernando Jorge and Sylvie Corbelin.

“While our business is based on trust in the authenticity of the natural-diamond jewelry that we buy and sell, it’s also based on the client’s trust in our integrity as jewelers,” Cayen explains. “Impostor stones represented as natural diamonds can cause major problems for retailers who unknowingly sell them. In turn, customers who discover through testing after purchase that theirs is not a natural diamond are understandably disappointed, angry, or worse.”

Businesses are responsible for correctly disclosing the nature of the diamonds they are selling, she asserts. “Unknowingly selling undisclosed laboratory-grown or other synthetic or treated diamonds as natural diamonds is the responsibility of the seller and can lead to commercial penalties and criminal charges.”

Regardless of whether charges are filed, selling a diamond that’s not natural — even unwittingly — to a customer who believes it is natural can damage jeweler-client relationships beyond repair, and can also destroy valuable trust between jewelers and their suppliers.

Looking to the labs

The desire to prevent such dilemmas has powered the development of technologies that verify natural diamonds. These tools can effectively safeguard members of the diamond and jewelry trade — and by extension, consumers.

“The need for natural and laboratory-grown diamond certification services is increasing with each passing year,” says Debbie Azar, president and cofounder of New York-headquartered Gemological Sciences International (GSI). The group operates diamond and gemstone testing labs in the US and 16 other countries, including India, Israel, Belgium, Botswana, Dubai and Hong Kong.

“We are seeing an increase of treated diamonds coming through our laboratories around the world,” she reports. “We are also seeing a large increase in the number of undisclosed laboratory-grown diamonds present in jewelry that is represented as natural-diamond jewelry.”

While there are several highly accurate, vetted verification instruments that businesses can order for their own office use — including some that are portable and small enough to fit on a desktop — it can be hard to authenticate all the stones that come through jewelers’ doors.

“Many retailers and others in the industry know that their manufacturers and suppliers lack the knowledge, equipment and processes to overcome this situation [of undisclosed lab-grown and treated diamonds],” acknowledges Azar. As a result, “they are increasingly insisting on having diamonds and jewelry certified or verified through testing laboratories such as GSI,” as well as other eminent labs such as the Gemological Institute of America (GIA), which has branches in 11 countries.

Enter the melee

One of the most potentially useful services is melee testing, since these small diamonds often go unverified by jewelers. One leader in this field is the Swiss Gemmological Institute (SSEF), which is part of the Swiss Foundation for the Research of Gemstones and which issues reports for natural diamonds, colored stones and pearls.

In collaboration with other partners, the SSEF created the Automated Spectral Diamond Inspection (ASDI), which analyzes and authenticates large quantities of colorless melee diamonds at a low cost. The ASDI can separate diamond imitations, synthetics, and High Pressure-High Temperature (HPHT)-treated diamonds, and can do customizable size-sorting as well.

“Some major Swiss diamond suppliers and prestigious Swiss jewelry and watchmaking companies have purchased ASDI machines for their facilities,” says Jean-Pierre Chalain, head of SSEF’s diamond department and vice president of the World Jewellery Confederation (CIBJO) diamond commission. “Since the 2014 debut of the ASDI machine, SSEF has tested millions of diamonds with this technology.”

The GIA, too, has developed an automated system to identify lab-grown and treated diamonds that may have been mixed into parcels of melee. The GIA Melee Analysis Service separates both round and fancy-shaped mined diamonds from simulants, lab-grown stones, and HPHT-treated diamonds. For an additional charge, it can sort round, D to Z melee by color range as well. Among other options, clients can specify a size range they want tested in their round melee parcels, and can also request sorting of fancy-colored diamonds. Once the melee is sorted, the GIA seals it in secure packaging and ships it back to the client.

Passing the test

How accurate are the various diamond verification devices on the market? An initiative called the Assure program has made efforts to find out by testing the testing equipment. Leading diamond trade organizations such as the Natural Diamond Council (NDC) have collaborated with equipment manufacturers to develop this standardized method “as part of a shared commitment to maintaining consumer confidence,” states NDC CEO David Kellie on the group’s website.

As of this writing, the NDC has reported on over 30 different verification instruments, and reviews are available on said website. Those with the highest diamond accuracy rates include De Beers’ SynthDetect and Diamond View systems, the GIA iD100, Alrosa’s Diamond Inspector, and Yehuda’s Sherlock Holmes (see Pages 18 to 19).

While retailers like Cayen send their melee and other diamonds for testing at gemological labs, she is contemplating purchasing a desktop diamond-verification device to screen the stones she buys for her bespoke commissions.

“It seems that investing in this type of equipment is a practical way to ensure that the diamond-jewelry side of our business runs as efficiently and accurately as possible,” she says. “I figure it is well worth it to me and my customers in the long run.”


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Where is Gemological Science International (GSI) located?

GSI is headquartered in New York, NY. It has 13 laboratories on four continents and in a number of countries: the United States, India, Dubai, Israel, Belgium, Hong Kong, and Botswana. This makes GSI one of the largest independent gemological organizations in the world.

Is there a difference between grading reports issued by different GSI laboratories?

All GSI laboratories grade using the same methods and adhere to the same standards. Every laboratory is staffed with highly trained professionals who have years of grading experience and an extensive gemological background.

What does it mean when a sales associate tells me my diamond is “GSI Certified” or is accompanied by a “GSI Certificate”?

The phrases “GSI Certificate” and “GSI Certified” are industry shorthand for GSI grading or identification reports. What this means to you is that expert gemologists and trained professionals meticulously evaluated the item. When your diamond, jewelry or gemstone is accompanied by a GSI grading report, you can be completely confident in the accuracy and objectivity of the evaluation.

Where can I find “GSI Certified Diamonds”?

GSI diamond grading and identification reports can be found in jewelry stores worldwide and online. Insist on a GSI grading report when shopping for a diamond, jewelry or gemstone.

What do I do if I lose my GSI Diamond Report?

Every GSI grading report is available on our website. Please visit and go to “verify your report”. Enter your GSI report number and you’ll instantly have access to a digital copy of it. You can also email us through the website to request a copy.

What are the 4Cs

A beautiful diamond is one of nature’s most mesmerizing creations. But how do you objectively judge the quality of the gem? The 4Cs – Cut, Color, Clarity, and Carat Weight – are the universal standard for doing this.

Is there anything beyond the 4Cs?

The 4Cs are an essential and important description of a diamond’s characteristics. But there is a considerable amount of detailed information behind each “C” along with other qualities of a diamond that affect its beauty, such as fluorescence, light performance and more.

How much do you need to know? That’s up to you, but knowing the 4Cs is almost essential.

What does a GSI diamond grading report look like?

GSI offers a number of grading reports (often referred to as “GSI Certificates”). You can see samples of them by browsing the Grading Reports page on our website.

What does a GSI colored diamond grading report look like?

You can see samples grading reports by browsing the Grading Reports page on our website.

What does a GSI Colored stone report look like?

You can see samples of Colored stones reports by browsing Grading Reports page on our website.

How does a GSI grading report compare to other laboratories that issue grading reports?

It is our policy not to comment on other laboratories. However, know that GSI adheres to the highest ethical standards. We do this in a number of ways:

  • Rotating gemologists to our different labs
  • Continuously upgrading our proprietary grading software to ensure full compliance with international grading standards
  • Having our gemological research department constantly investigate new developments in the industry, which informs the grading process

What’s the difference between a “GSI Certificate” and a “GSI Diamond Grading Report”?

GSI issues a variety of grading and identification reports. Consumers and industry professionals often call these reports “GSI Certificates”.

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