Make sure it has a certificate
There are different organisations that grade and certify diamonds. The top are GIA (Gemological Institute of America), HRD (Hoge Raad voor Diamant) in Europe, and IGI (the International Gemological Institute).
When they grade your diamond (determining its carat, cut, clarity and colour), their standards are not identical, and the same diamond may receive slightly different ‘ratings’ depending on which organisation has certified it.
However, as long as it has a certificate from an industry-recognised group, you can rest assured that your diamond is real, and that you know what you’re getting.
Make sure the diamond matches the certificate!
Yes, your diamond came with a piece of paper attached – but how do you know that the certificate relates to the diamond in hand? All diamonds weighing under 1 carat – and 75% of diamonds larger than 1 carat – with GIA certificates have a laser number, which matches its certificate number.
You won’t be able to see this with the naked eye, but any jeweller will be able to verify this with a powerful magnifying glass, and you can see this at Sterling Diamonds as well.
Check it is certified conflict-free
Almost every diamond dealer and jeweller nowadays will guarantee that your diamond is not a blood-diamond, mined in a conflict zone and used to fund a war or insurgency. To prove that they are conflict-free, rough diamonds will carry a Kimberley Process certificate, which certifies that the rough diamonds were shipped in a sealed, tamper-resistant container, and did not profit rebel movements.
Unfortunately, the problem has not been entirely eliminated, as some blood diamonds are smuggled to other countries where they can be fraudulently certified. Therefore, at Sterling Diamonds, we only use gems that we are certain are legitimately sourced, and every diamond we sell comes with the following guarantee:
“The diamonds herein invoiced have been purchased from legitimate sources not involved in funding conflict, in compliance with United Nations resolutions. The seller hereby guarantees that these diamonds are conflict-free, based on personal knowledge and / or written guarantees provided by the supplier of these diamonds.”
Watch out for HPHT treatment
Some diamonds have their colour upgraded synthetically through a process called HPHT, which involves subjecting them to very high temperatures and pressures in specialist equipment.
Once this happens (and, similarly, once a diamond has been subject to lasering to get rid of black impurities), it is no longer considered a natural diamond, but an “improved diamond”, with a vastly reduced value compared to a natural, untreated diamond.
This is normally disclosed on the GIA certificate, so check your certification.
When in doubt, consult a professional. There are many ‘tricks’ online to help you determine whether your diamond is real or fake. If you already possess a diamond, or have inherited a diamond, without the relevant certification, don’t mess about with guesswork – take it to a professional diamond dealer, jeweller or gemologist, who will appraise it for you properly, using specialist equipment.
They will be able to tell you whether your stone is real, whether it is natural, whether it has been treated in any way and what (approximately) it is worth. If you do have certification, they can tell you whether the gem matches the documentation; if you don’t, you can get it properly graded and certified.