When you go to buy a diamond for your engagement ring, it should always be certified. This means it’s been inspected by an independent laboratory and graded on a host of specifications including measurements, color, clarity, inclusion placement and type, and the quality of the cut. The certificate has a number that acts like the VIN for your car - it’s a unique identifier that’s laser inscribed on the girdle of your diamond. You should never purchase an uncertified diamond, or one that’s been “certified” by the seller. No one should be grading their own homework!
The two most common independent diamond graders are the International Gemological Institute (IGI) and the Gemological Institute of America (GIA). Most lab diamonds are graded by IGI, and some are graded by GIA.
So - does it matter who graded your diamond, IGI or GIA? The answer is a little complicated.
The first thing to know is - although it sounds obvious - all diamonds are graded by humans. That means there’s always a little bit of a margin for error. While diamond certificates are usually correct, we at Hera have come across diamonds that we would have graded differently, such as a diamond graded as G color that looks more like an H to us. This happens with GIA and IGI stones occasionally. Your diamond should always be checked by an expert to make sure that the stone truly does match the certificate.
When people are concerned about their certificate, this is often what they’re worried about: overpaying for a stone that’s been graded too generously. While it can happen with any grader, we see this most often - but still rarely - with diamonds graded at IGI’s India office. This is where most lab diamonds in the world are graded, which is why if you’re buying a lab diamond, it’s especially important that an expert has checked it for you.
This isn’t to say that IGI is a bad laboratory by any means - IGI has very rigorous graders around the world at offices like IGI New York, and most of IGI India’s stones are also graded correctly. Hera works closely with IGI and, because we specialize in lab diamonds, we understand the nuances of diamond grading at different locations so we can make sure you’re always getting the very best.
