IGI vs GIA: Which Diamond Certification Should You Trust?

When you're buying a diamond engagement ring, certification matters. It's the document that tells you, in objective third-party terms, exactly what quality of stone you're getting. The two most commonly referenced bodies for engagement ring diamonds in Australia are IGI (International Gemological Institute) and GIA (Gemological Institute of America). Here's how they compare.

What is diamond certification?

A diamond certificate, also called a grading report, is issued by an independent gemological laboratory after it has assessed a diamond's four key characteristics: cut, colour, clarity and carat weight. It isn't produced by the jeweller or retailer. It's an objective third-party assessment.

The certificate tells you exactly what you're paying for. Without it, you're relying on the seller's word.

GIA: the original standard

GIA is widely considered the benchmark for mined diamond certification. It developed the four Cs grading system in the 1950s and has been the most trusted name in diamond grading for decades. GIA grading is known for being conservative: a GIA G-colour diamond is reliably a G, where some other labs might grade that stone an F.

GIA was slower to fully embrace lab-grown certification. It now grades lab-grown diamonds, but its lab-grown reports don't carry the same colour and clarity grades on the main document as its mined diamond reports, listing ranges rather than specific grades for some characteristics.

IGI: the lab-grown specialist

IGI has become the dominant certification body for lab-grown diamonds globally. It was early to embrace lab-grown certification and has graded millions of stones. Its lab-grown reports are comprehensive, providing specific colour and clarity grades just as they do for mined stones.

IGI grading is generally considered slightly more lenient than GIA for mined diamonds, but for lab-grown stones, where it has the most experience and the largest comparison dataset, IGI is the industry standard.

Which should you trust?

For lab-grown diamond engagement rings, an IGI certificate is the most appropriate and widely recognised choice. It gives you specific, reliable grades you can use to compare stones.

At Una Diamond, centre stones of one carat and up are IGI certified. IGI sets that one carat threshold, not us.

Ready to find your ring? Explore our lab-grown diamond engagement rings.

IGI Certification at Una Diamond

Centre stones of one carat and up come with an IGI certificate. Browse our handcrafted collection:

• The Georgina, oval-cut solitaire
• The Celina, emerald cut
• Solitaire rings
• Oval cut rings
• Browse all rings