How Are Man-Made Diamonds Graded?

Certifying & Grading Lab-Created Diamonds

Lab-created diamonds are graded and certified using the same process as mined diamonds.

Diamonds are sent to a gem lab that specializes in grading diamonds. The majority of these labs grade using the 4Cs (Cut, Color, Clarity and Carat), however, a select few use their own criteria.

The most popular diamond certification labs are the Gemological Institute of America (GIA) and American Gem Society (AGS)

Grading Man-Made Diamonds

Grading man-made diamonds.

The diamond grading process is roughly the same for all of the diamond certification labs. Each diamond is graded independently by several gemologists at the lab. The individual grades are compiled and analyzed to determine the final grade.

This process is designed to provide each diamond with an unbiased grade. However, it's not uncommon for a diamond to get a different grade, not only from a different lab but from the same lab if sent back for a second grading.

For this reason, there are a lot of differing opinions amongst consumers and diamond retailers as to which lab is the "best.' But, it's important to keep in mind that those opinions are completely subjective. Each lab, much like anything in life, has its pros and cons.

A diamond retailer chooses which lab they use because they trust that lab to grade diamonds fairly. If diamond certification is an important factor in your purchase, you should have a candid conversation with your jeweller about which lab they use and why.

More than anything, jewellers want you to be confident in your purchase, so don't be afraid to ask questions in order to find the best lab-created diamonds for your engagement ring or engagement ring jewellery.

As mentioned, a diamond is evaluated using the 4Cs - cut, clarity, color, and carat. Basically, they judge the diamond on how well it has been cut down from its raw form into a jewel, how flawless and clear it is, and its size.

Man-made diamonds have been extensively studied by gemological researchers for the past 30 years, and much is known today about how they are grown and how they can be identified.

Synthetic diamond identification means distinguishing a natural diamond that formed over a long time ago, from a synthetic diamond that formed very quickly and very recently.

GIA has screened every diamond submitted to its laboratory for grading for more than a decade to determine if it is natural or potentially man-made or treated. Following the initial screening, any diamond that is potentially man-made or treated undergoes rigorous examination to confirm if it is natural or man-made, and what treatments, if any, have been applied.

GIA can definitively identify both HPHT and CVD-created man-made diamonds.

GIA Grading Report

GIA began to offer a report service for synthetic diamonds in 2006. These Synthetic Diamond Grading Reports, which GIA continues to offer, are distinct from GIA grading reports for natural diamonds in both their appearance and the information provided. They clearly identify that the diamond is man-made or laboratory-grown, and they evaluate color and clarity using descriptive ranges rather than the specific grades of the color and clarity scales.

When these reports were introduced, there was a range of opinion in the trade about GIA grading synthetic diamonds. Since synthetic diamonds continue to be rare, and to differentiate them from what is reported on grading reports for natural diamonds, only color and clarity ranges are used.

In addition, the man-made diamond's girdle is laser inscribed with its report number and a statement that the stone is laboratory-grown. GIA does this for every man-made diamond identified in its labs.

The inscription on the girdle can be key to its identification.

The reports also use the other Federal Trade Commission (FTC) approved terms, man-made and lab-grown, for synthetic diamonds. There are legal and ethical requirements that a jeweller must disclose a gem's identity at the time of sale. This helps ensure consumer confidence in what they are purchasing.