What is IGI diamond certification?
By Jared James · Last updated 21 May 2026
Definition
IGI stands for the International Gemological Institute, a gemological laboratory founded in Antwerp in 1975 and one of the largest diamond grading organisations in the world. It grades diamonds and gemstones across its network of laboratories using the standard 4 Cs framework of cut, colour, clarity and carat weight. IGI has become particularly prominent for grading lab-grown diamonds, and many retailers who specialise in lab diamonds offer IGI-certified stones alongside or instead of GIA-graded ones.
Frequently asked questions
- Is IGI as trustworthy as GIA?
- GIA is widely considered the benchmark and is the most conservative in its grading, which means a GIA-graded stone is generally held to a slightly stricter standard. IGI is a reputable and widely recognised laboratory, though historically its grades for natural diamonds have sometimes been seen as one step more generous than GIA. For lab-grown diamonds specifically, IGI is very commonly used and well-regarded.
- What does an IGI certificate tell you?
- An IGI report lists the diamond's cut, colour, clarity and carat weight, along with measurements, polish, symmetry and fluorescence. For lab-grown diamonds it also confirms the growth method used. It gives you an independent description of the stone you are buying.
- Should I buy an IGI-certified diamond?
- Having any independent certificate is better than none, as it gives you a clear description of the stone and protection if the quality is misrepresented. If you are comparing prices, bear in mind that a GIA Excellent and an IGI Excellent grade are not always identical in practice, so it is worth looking at the actual diamond rather than just the paperwork.
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