IGI vs. GIA Certification: What It Means for Your Lab-Grown Diamond

When you buy a quality diamond, it should come with an independent grading report. The two most respected labs are IGI (International Gemological Institute) and GIA (Gemological Institute of America). Both are reputable — here's what sets them apart for lab-grown diamonds.

What a certificate actually does

A grading report is an unbiased, third-party assessment of a diamond's 4Cs — carat, color, clarity, and cut — along with measurements and, for lab-grown stones, often the growth method (CVD or HPHT). It's how you know the diamond is exactly what's described, rather than taking the seller's word for it.

IGI: the standard for lab-grown

IGI grades the large majority of the world's certified lab-grown diamonds — an estimated 70%+ — and is the lab most specialist retailers rely on. It's known for fast turnaround, detailed lab-grown reporting, and consistent grading. For lab-grown diamonds specifically, an IGI report is fully reliable and the industry norm.

GIA: the most prestigious name

GIA is the most widely recognized grading authority and is often considered the benchmark for natural diamonds. It was slower to embrace lab-grown stones but, since a 2023 update, now issues full color and clarity grades for them. GIA grading tends to run about one grade stricter than IGI on color and clarity, and GIA reports can carry a premium that's reflected in the diamond's price.

So which should you choose?

• For most lab-grown buyers, IGI is the smart choice — reliable grading, excellent lab-grown expertise, and better value, since you're not paying extra for the report itself.
• Consider GIA if maximum brand prestige is a priority for you and you don't mind paying more for the name.

The most important thing is simply that your diamond is independently certified by a recognized lab — not uncertified.

How we certify at Zack & Elle

Every Zack & Elle diamond over one carat is independently IGI-certified and laser-inscribed with its report number, so you can verify your exact stone. You get trusted, transparent grading — and the value that lab-grown is known for.

Browse our certified lab-grown diamonds or contact us with any questions about certification.