#6 Certificate of authenticity
Image Source: Nicholas Eckhart
This is something else you can consider in combination with the other tests included here. Obviously, it’s possible for documents to be forged, but it is worth examining this carefully if the seller can present one to you. You may be able to get an opinion regarding the legitimacy of the document by bringing it to a reputable jeweler, who may be willing to examine it and give you’re their opinion in the document at no cost.
