GIA vs IGI diamond certificates: what they mean

When you buy a certified diamond, the certificate matters almost as much as the stone. It is an independent assessment of what you are actually getting. The two laboratories you will see most often are the GIA and the IGI. Both are respected, and we supply diamonds certified by either, but they are not identical.

What a diamond certificate is

A diamond certificate, or grading report, is an independent laboratory's assessment of a stone's quality. It records the 4Cs (carat, cut, colour and clarity) along with measurements, proportions and any treatments. It is not a valuation; it describes the stone, not its price. If the 4Cs are new to you, start with our guide to diamond cut.

The GIA

The Gemological Institute of America created the modern 4Cs grading system, and it is widely regarded as the strictest and most consistent laboratory. A GIA report is the benchmark for natural diamonds, particularly at the higher end. Because GIA grading is conservative, a stone will often grade half a step lower than it might elsewhere, which is part of why the report is so trusted.

The IGI

The International Gemological Institute is a large global laboratory and the dominant name in lab-grown diamond certification. For lab-grown stones, an IGI report is the standard you will see most often. IGI also grades natural diamonds; its grading is reliable and its reports are clear and detailed.

A report is also how you meet a diamond in the first place. The studio is by appointment and there is no loose stock to browse, so you work from reports, images and video matched to your brief. If the stone is where you would rather start, you can choose the diamond first and have the ring designed around it.

Which should you choose?

• For a natural diamond, particularly a larger one, a GIA report gives the most widely recognised assurance.
• For a lab-grown diamond, IGI is the established standard and entirely trustworthy.
• Whichever you choose, insist on a stone that is certified. An uncertified diamond is one you take on trust alone.

GIA or IGI certification is available on every centre diamond we supply, and we talk you through the report so you understand exactly what you are buying. To begin, tell us what you are looking for.