Lets talk certs!!… when buying a diamond engagement ring you often hear a lot about diamond certs. Good ones, bad ones and none at all. So what’s the difference and when should you have or not have diamond certs. Below are a few examples of certs you will come across in the diamond trade. There are many many labs in the world and each of them have their own standards of diamond grading. I have seen certs from all labs which I have disagreed with. The first point to make and the most important one is that diamond certs are OPINIONS ONLY… The following picture is taken from the terms written on the back of a cert from the GIA (Gemological Institute of America).




Around the world there are varying standards of grading and one labs opinion can vary greatly from another. In some cases this affects the value of the stone dramatically which is why it is very important that if you are offered a cert with a diamond that you trust the source. If I disagree with a diamond cert when buying it I normally take a decision to have it regraded. The quality of a lab cert is entirely dependant on the person grading it on the day with variations. Recently I bought a 2.21ct cushion cut diamond on a particular cert. I did not agree with the cert and had it redone. The original cert had the grade as a G VVS1 . ( I however bought it on the basis of what I considered it to be, an I. ) The results are shown below.

As you can see the colour change from the G to the I in this particular stone has a huge impact on the value of the diamond. Also the clarity grade change in a stone this size is also dramatic. Colour and clarity can be very subjective when dealing with stones that are borderline or between grades. One lab can give a vs1 and another a vs2. Based solely on the opinion on the diamond grader. The important thing to realise is that a cert gives you a secondary opinion and can give piece of mind when buying a diamond. It is not to be taken as fact written in stone. Judge a diamond on its merits. Is it bright?. Is it sparkly?. Does it appeal to you. Older cut stones have beautiful fire in them and usually less brilliance. Newer cut stones usually have more brilliance but less fire. I am often asked which is “Best”? older or newer cuts? Is a Picasso better than a Vermeer? That is up to you.

I never buy diamonds on certs alone as it tells you nothing about the overall aesthetic and beauty of a diamond. They are nice to have so that you can be assured that they are in fact diamonds and good quality stones at that, but beauty is in the eye of the beholder.

When we buy a beautiful old diamond ring, it will not usually come with a cert. Sometimes its ok to take the stone out of the setting and get it certed. However we cannot do that with all old rings as doing so could destroy the beautiful old setting. In those cases I give my opinion on the qualities without removing the stones.



Here are the links to some of the more well known labs.














Below is a breakdown of how a cert is broken up.

















Note on the cert below for the sapphire that “Evidence of heat treatment was observed”. In most sapphires heat is applied to get that beautiful blue hue. Sapphires with no heat are highly prized and generally worth more that those that have been heated. It should be noted that the majority of sapphires around 95% are heated.