Sometimes known as the fifth "C" of diamond buying, it is critical to know what a certificate is and why it is so important to have for your diamond.
A diamond certification is done by an independent laboratory staffed with experienced, professional gemologists who specialize in evaluating diamonds. During this evaluation, a series of tests and tools will be used to analyze the diamond’s cut, color, clarity, carat weight, dimensions, polish, symmetry, and more. All of these findings will be detailed in the certification. Different Laboratories use different names for their certificates for example: GIA Diamond Grading Report, GIA Diamond Dossier®, AGSL Diamond Quality Document. Each certificate provides varying degree of detail about a diamond. The most credible laboratories in the jewelry industry are the Gemological Institute of America (GIA) and the American Gem Society (AGS) Laboratories.
For security and longevity purposes, the final certificate is laminated and sent with the diamond back to whoever sent it in. This certificate should then forever travel with the diamond, from seller to buyer and beyond. It is proof of everything the diamond is – and isn’t. Note that a certificate isn’t an appraisal. Rather, it certifies a gem’s characteristics without assigning a monetary value.
If you purchase a diamond without a certificate, you are essentially taking the seller at his word that the diamond you are purchasing actually has the specifications he presents you with. While no one likes to appear untrusting, it’s not unreasonable or unusual to expect a diamond presented for purchase be accompanied by a certificate. If you find a diamond that you like that lacks a certificate, you can always request the seller have it certified by an independent gemological lab.
This is a common and sensible request, and one the seller has no realistic reason to refuse. If he or she does, cancel the transaction immediately and choose a new jeweler to do business with. Similarly, if the only certification provided was done in-house or by the jeweler you’re dealing with, this may be a red flag. The reason certification is done by independent labs is to mitigate any self-serving influence by evaluating the gems in a completely non-biased, objective setting by gemologists who have no personal stake in the findings.
The Gemological Institute of America (GIA) is the foremost gem laboratory in the world. Although there are certainly other reputable labs, not all labs are created equal. Introduced in 1953, the standards for gem grading created by GIA are now internationally recognized, and all respectable labs follow those standards. GIA has the most advanced gem lab and instruments in the world and are the most stringent and consistent in their grading. A certificate issued by GIA can be relied upon as coming from a trusted source known for their accurate, comprehensive and conscientious evaluations.
If a jeweler offers you a certification done by a laboratory other than GIA or AGS, don’t be afraid to ask for that lab’s credentials – and don’t be afraid to take the time to verify them. Like a house or a car, a diamond is a big purchase. You’ll never regret taking a little extra time and energy to assure yourself that what you’re being offered is what you’re actually getting.