A diamond is only as trustworthy as its certificate. Two stones can look identical and carry very different price tags — the difference is in the grading report. Here's what diamond certification means, and how the two labs we trust, GIA and IGI, compare.
What is a diamond certificate?
A diamond certificate (or grading report) is an independent, third-party assessment of a diamond's exact quality — its 4Cs: cut, color, clarity, and carat, plus measurements and other details. Because it comes from a lab with no stake in the sale, it's a fact about the stone rather than a seller's claim. When you buy a certified diamond, you know precisely what you're paying for.
GIA: the global gold standard
The Gemological Institute of America (GIA) created the modern diamond grading scale and is widely regarded as the strictest, most consistent lab in the world. A GIA report is trusted everywhere, which is part of why GIA-graded diamonds often command a premium.
IGI: trusted and consistent at scale
The International Gemological Institute (IGI) is a long-established global lab, and it has become especially prominent for grading lab-grown diamonds at scale. IGI reports are detailed, consistent, and trusted by retailers worldwide.
GIA vs IGI: which should you choose?
Both are reputable. In practice, natural diamonds often come with GIA reports and lab-grown diamonds often come with IGI reports — but what matters is that your diamond is graded by a lab you can trust, and that you're comparing like with like (a GIA report against a GIA report). Don't compare an uncertified stone's "price" to a certified one; you're not buying the same thing.
Why we certify every diamond
Every diamond at Tessera — lab-grown or natural — is certified by GIA or IGI. We deliberately list only stones graded by labs we trust; you can read our full quality standards, and you see the complete report and final price before you commit. Start with a setting you love, then choose your certified diamond.