GIA and IGI are the two certification labs Dubai buyers see most often, and their grades aren’t interchangeable. GIA is the stricter, more conservative lab and the standard for natural diamonds. IGI grades slightly more leniently and dominates lab-grown certification. The difference affects price, and it affects what a diamond is actually worth if you resell it.
Quick take:
- GIA grades more conservatively and carries more resale weight, especially on natural diamonds.
- IGI grades slightly more leniently and dominates lab-grown certification, usually at a lower price for the same stated grade.
- Since October 2025, GIA no longer uses letter grades for lab-grown stones. It labels them Premium or Standard instead.
- Whatever the lab, an uncertified diamond is the real risk, not a gap between two legitimate certificates.
The confusion buyers actually run into
Two diamonds can look nearly identical, carry the same stated grade, and still sell for noticeably different prices in Dubai, simply because one came with a GIA report and the other with an IGI report. Most buyers assume a grade means the same thing regardless of which lab issued it. It doesn’t.
The gap isn’t fraud on either side. GIA and IGI are both legitimate labs, they just don’t grade to the same standard. GIA has built its reputation on being conservative, sometimes grading a stone a full step lower than IGI would on the same clarity or colour. That gap is exactly why two similarly priced diamonds with different certificates aren’t always the same deal they look like on paper.
What GIA, IGI, and the rest actually mean
GIA, the Gemological Institute of America, is the lab most of the industry treats as the benchmark. It’s a nonprofit, it created the 4Cs framework most jewellers still use, and its grading is widely regarded as the strictest in the trade. That reputation is also why GIA certified stones tend to hold resale value best. Dealers and buyers alike default to trusting a GIA number.
IGI, the International Gemological Institute, has been grading diamonds since 1975 and has become the dominant lab for lab-grown diamonds specifically. Its grading tends to run a little more generous, often by around a full grade on colour or clarity, which is part of why IGI certified diamonds are usually priced a bit lower than a GIA equivalent at the same stated grade. That’s not a flaw, it’s a different standard, and it’s worth knowing before comparing two price tags.
One recent change worth knowing: since October 2025, GIA stopped grading lab-grown diamonds on the traditional colour and clarity scale. A GIA lab-grown report now reads Premium or Standard instead of a letter grade. IGI still grades lab-grown stones the familiar way, which is part of why IGI remains the more common certificate on lab-grown pieces.
| Lab | Reputation | Best known for | What it means for you |
| GIA | Strictest, most conservative | Natural diamonds, the industry benchmark | Best resale confidence, usually the highest price for a given grade |
| IGI | Slightly more lenient, roughly a grade looser | Dominant for lab-grown diamonds | Lower price for the same stated grade, still fully legitimate |
| EGL | Inconsistent, grades often inflated | Rarely used by reputable retailers today | Worth avoiding, or re-verifying independently |
Other names show up occasionally too. AGS, the American Gem Society, is a smaller but respected lab, particularly for cut grading. EGL is the one worth being cautious about. Its grades have a reputation for running noticeably higher than GIA on the same stone, sometimes by a full grade or more, which shows up as a lower price that isn’t actually a better deal.
What we tell customers who ask us this
This is one of the most common questions we get once someone’s comparing two stones side by side. It comes up most with engagement ring and solitaire pendant customers, where the stone is the whole piece and a full grade of difference in the certificate actually shows up in the price. When someone brings two options to the counter, one GIA and one IGI at what looks like the same grade, we lay both reports out side by side and walk through them line by line so the difference is visible, not just something we’re asserting. The short version we give in person: for a natural diamond you plan to keep long term, GIA is worth the extra cost. For a lab-grown piece, IGI is the practical standard and there’s little reason to pay more for GIA. Either way, we verify every certificate against the issuing lab’s own lookup tool before a customer buys, since a certificate number that doesn’t match the stone is a bigger problem than any grading gap between labs.
About the author
Muneer Thangals leads Thangals Jewellery, the business his father founded in 1974. Verifying certification is a routine part of buying and selling diamonds at that level, and the comparisons in this guide come from that hands-on experience with GIA and IGI reports.
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Common questions
Is IGI as reliable as GIA?
IGI is a legitimate, internationally recognised lab. Its grading tends to run slightly more leniently than GIA’s, so an IGI grade and a GIA grade on the same stone aren’t always directly comparable, but that doesn’t make an IGI report unreliable.
Does diamond certification affect price?
Yes. A GIA certified diamond typically costs more than an IGI certified stone at the same stated grade, largely because GIA’s grading is stricter and carries more resale confidence.
Should I choose GIA or IGI for a lab-grown diamond?
IGI is the more common and practical choice for lab-grown diamonds. GIA now grades lab-grown stones as Premium or Standard rather than using the traditional colour and clarity scale.
