Re-certification or verification refers to taking a certified diamond to an independent appraiser or laboratory to double check the gradings on the laboratory certificate.
Every diamond grading certificate has a little disclaimer saying words to the effect that they’re not responsible for the grades on the certificate and that you should consult a qualified gemmologist or jeweller.
This would be akin to going to a bank, depositing money and receiving a slip with a disclaimer saying that there’s no guarantee that you’ll get your money back. Hence, buying a diamond should be no different, since every consumer good by law comes with some kind of warranty. Even money deposited in a bank is guaranteed by the Reserve Bank.
Certificate verification or re-certification is a cheap and easy way to virtually guarantee the quality of the diamond you are going to purchase.
The two labs we use for re-certification and verification are Gem Studies Laboratory and Bauer Gemmological Laboratories. Both of which are staffed by former presidents of The Gemmological Association of Australia.