IGI Certified Diamonds

The International Gemological Institute grades more diamonds than any other laboratory in the world, and it grades the overwhelming majority of lab-grown stones. If you are shopping grown diamonds anywhere, you are almost certainly reading IGI reports.

That concentration is genuinely useful. The single hardest thing about comparing diamonds across sellers is that laboratories differ in strictness, so two stones with the same letters are not always the same stone. Within IGI-graded inventory that problem largely disappears: the reports are internally consistent, which means a VS1 here is a VS1 there, and the comparison you make on screen is the comparison you would make with both stones in front of you.

An IGI report carries the full picture — cut, colour, clarity, carat, measurements, proportions, fluorescence, and for grown stones the growth method — along with a plotted clarity diagram. Every report number is printed on the product page and can be checked against IGI's own database before you spend anything.

We list IGI alongside GIA rather than instead of it, and each stone states its laboratory plainly. Both come with a 360° video, which is still the only way to see a bow-tie or a dull crown.