Every diamond we sell is certified by IGI or GIA, and buyers sometimes ask which one is "better." It's a reasonable question, the two labs do have real differences, but the answer matters less than most people expect once you understand what a certificate is actually for.
The short answer
Both IGI (International Gemological Institute) and GIA (Gemological Institute of America) are independent, third-party labs, meaning neither is affiliated with the jeweler selling the stone. Both grade diamonds using the same fundamental 4Cs criteria: cut, color, clarity, and carat. The practical differences come down to history, specialization, and report format, not which lab is more "legitimate."
GIA: the lab that created the 4Cs system
Founded in 1931, GIA developed the 4Cs grading system that the entire industry now uses, including IGI and every other gemological lab. GIA has historically focused heavily on natural diamond grading and is widely regarded in the trade as a conservative, strict standard, which is part of why "GIA-certified" carries strong recognition, particularly for natural diamonds.
IGI: the lab that grades most of the world's lab-grown diamonds
Founded in 1975, IGI is the world's largest independent gemological institute by volume, and it certifies a large majority of lab-grown diamonds specifically, including most of what you'll find at MIRA Studio. IGI generally offers faster turnaround than GIA and has built specific expertise in lab-grown diamond identification and grading as that category has grown.
Does grading actually differ between the two?
Some jewelers in the trade note that IGI grading can run slightly more generously than GIA on comparable stones, though this is a matter of industry perception and normal variation between any two labs rather than a documented, quantified gap. The more useful takeaway: both labs grade using the same criteria, and both are independent of the seller, which is the property that actually protects you as a buyer. A diamond's grade tells you about that specific stone; which of the two reputable labs issued the report tells you comparatively little about the stone itself.
Report format
Both labs issue a document listing the stone's shape, measurements, cut, color, clarity, carat weight, and a unique report number that can be verified directly with the issuing lab. GIA's reports for lab-grown diamonds are formatted distinctly from their natural-diamond reports; IGI issues a single consistent report format across both. Neither difference affects the diamond itself.
What actually matters when you're buying
- That it's independently certified at all, by either lab, rather than only graded in-house by the seller.
- The specific grades on the report (cut, color, clarity, carat), which describe the actual stone you're buying, matter more than which lab issued them.
- The report number is verifiable directly on the issuing lab's website, which is worth checking for any meaningful purchase.
Frequently asked questions
Is a GIA certificate worth more than an IGI certificate?
Not in a way that should change your decision. Both are independent, reputable labs grading on the same criteria. GIA carries more historical brand recognition, particularly for natural diamonds, but that's a reputation factor, not a difference in what the certificate verifies.
Why do most lab-grown diamonds come with IGI certificates instead of GIA?
IGI certifies the large majority of lab-grown diamonds globally and has built specific expertise and faster turnaround for that category, which is why it's the more common certification for lab-grown stones specifically.
Can I verify a diamond's certificate myself?
Yes. Both IGI and GIA let you look up a report by its number directly on their websites to confirm it matches the stone you were shown.
Does certification affect a diamond's price?
Indirectly, since the grades on the certificate (cut, color, clarity, carat) are what determine price, not the choice of lab itself. A stone independently graded to a certain standard is priced according to that grade regardless of which reputable lab issued it.
Shop certified stones
Every diamond across our rings, stud earrings, and necklaces is independently certified by IGI or GIA, with grading details listed on each product page.