IGI (International Gemological Institute)

IGI was founded in Antwerp, Belgium, in 1975. It provides grading and certification for diamonds (natural and lab-grown), gemstones and jewellery, and it runs schools of gemology. At its 2024 share offering it reported 31 laboratories and 18 schools of gemology in 10 countries.

The ownership is worth knowing. A Singapore subsidiary of Blackstone, a private equity firm, bought IGI in May 2023 from China's Fosun Group for about US$570 million, and IGI's Indian subsidiary made a public share offering in India in December 2024. IGI is a for-profit company. That is a plain structural difference from GIA, which is a nonprofit. It says nothing, good or bad, about the quality of the grading.

In its 2024 share offering prospectus, IGI estimated that it accounted for about 65 per cent of the global lab-grown diamond certification market and about a third of the overall grading-report market. These are the company's own estimates, not an independent count. They explain what you see when you shop: a lab-grown stone with an IGI report is very common.

That volume is not a quality grade. It tells you the lab is established in the lab-grown market, nothing more. As with any report, what matters is that the number on the report matches the number on the stone and that the description matches the stone you are holding.

Both are respected laboratories, and a buyer in Mississauga or Brampton will meet reports from both. The table sets out the differences that can be checked, without ranking them.

One practical point follows from the table. Each lab runs its own grading process and publishes its own report layout, so two stones with the same letters on paper from different labs are not guaranteed to look the same. Read each report on its own terms, and then look at the stone, in person or on a good video. How to read a diamond grading report walks through both formats.

Use the same three checks you would use for any lab. First, look for the report number as a laser inscription on the girdle, which you can read with a 10x loupe, and compare it with the number on the report. Second, enter the number into the lab's own online lookup on its website. Use the address you type yourself, not a link a seller sends you. Third, compare what the lookup shows with the paper or PDF: shape, carat weight, colour, clarity and measurements.

If the stone is already set in a ring, a bezel or prongs can cover the girdle. Ask for the report number in writing and check it online.

Choose it because the stone is right for the ring and the report describes it accurately. A report from a recognized lab is a sensible baseline for a centre stone, whether the diamond is natural or lab-grown. It is a description, not a valuation, so ask for a separate appraisal once the ring is made.

If you are weighing lab-grown against natural, lab-grown vs natural diamonds covers the trade-offs. If you are shaping a ring around a particular stone, the custom engagement ring page explains how a bespoke order starts, and the design studio lets you try settings before you commit.