Two respected labs, one logical choice. Here is which certificate matters for a lab grown diamond, and why.
The Short Answer
For lab grown diamonds, IGI is the smart choice; for natural diamonds, GIA is the gold standard. GIA grades more strictly and carries the strongest resale recognition, but commands a 5–10% premium. IGI certifies roughly 70% of lab grown diamonds, is faster and more affordable, and grades slightly more leniently (about half a grade to a grade). For a lab grown stone, a reputable IGI report at a sensible quality floor gives you everything you need.
A grading certificate is your diamond's proof of quality, so choosing which lab you trust is a genuinely useful thing to understand before you buy. The good news is that the two names you will see most, IGI and GIA, are both reputable, and the right pick is refreshingly logical once you know how each is used. Let me clear it up the way I would for a customer at the counter.
We'll cover what each lab is, how their grading differs, and exactly which to choose for a lab grown diamond. For the full context, our complete guide to lab grown diamonds ties it together, and how lab grown diamonds are made explains what gets graded.
Every Aquamarise lab grown diamond ships with an independent IGI report.
What GIA Is — The Gold Standard
The lab that literally invented modern diamond grading.
The Gemological Institute of America, founded in 1931, is a non-profit and the organization that created the 4Cs grading system the whole industry uses. It is renowned for the strictest, most consistent grading in the trade, which is why GIA reports carry the strongest resale recognition and why dealers and auction houses default to them. That rigor comes at a cost: GIA grading is slower and more expensive, and GIA-certified diamonds command a price premium of roughly 5 to 10 percent for the same stated grade.
For a natural diamond, especially a larger one, that premium can be worth it for the confidence and resale strength. Historically GIA graded few lab grown diamonds, and in late 2025 it moved lab grown reports to descriptive Premium and Standard tiers rather than the full color and clarity scale, reinforcing that lab grown and natural are now treated as distinct market segments.
What IGI Is — The Lab Grown Leader
The lab that grades most of the world's lab grown diamonds.
The International Gemological Institute, founded in 1975, is one of the largest gemological labs in the world and the practical default for lab grown diamonds, grading an estimated 70 percent of them. IGI built dedicated lab grown grading protocols early, operates screening labs near the major manufacturing hubs, and issues detailed reports that cover the full 4Cs, confirm the stone is laboratory grown, and typically note the growth method (CVD or HPHT). Its certification is faster and more affordable than GIA's, and those savings are passed to you.
IGI is widely regarded as grading slightly more leniently than GIA, by roughly half a grade to a grade on color and clarity. That is not a flaw so much as a calibration difference; you simply account for it by setting a sensible quality floor. Every Aquamarise lab grown diamond ships with an IGI certificate for exactly these reasons: it is the lab grown standard, it is reliable, and it delivers better value.
The Key Differences — Side by Side
Everything that actually matters, in one view.
| Factor | IGI | GIA |
|---|---|---|
| Best for | Lab grown diamonds | Natural diamonds |
| Lab grown market share | ~70% (the leader) | Small |
| Grading strictness | Slightly more lenient | Strictest |
| Cost & speed | More affordable, faster | Premium, slower |
| Price impact on stone | Lower for same grade | 5–10% premium |
| Resale recognition | Strong for lab grown | Strongest overall |
A helpful rule of thumb: an IGI "VVS2 / E" lab grown diamond looks, in the real world, much like a GIA "VS2 / F" stone, still beautiful and eye-clean. So rather than chase a GIA report on a lab grown diamond, you get more for your money by choosing an IGI stone and aiming a notch higher on color and clarity. For how these grades translate to price, see our lab grown diamond price guide.
Always Verify — Two Minutes That Protect You
The single most important habit when buying certified.
Counterfeit reports exist and serial numbers can be cloned, so never trust a printed or PDF certificate on its own. Both labs offer free, instant online verification: enter the report number on IGI's or GIA's official website and confirm the grading matches the stone in front of you. Do this before you pay, every time. It takes two minutes and it is the surest protection you have. Our diamond transparency commitment explains how we document every stone, and if you ever need a written valuation for insurance, our jewelry appraisal page walks you through it.
Why We Certify Every Stone — Peace of Mind, Standard
Certification is not a nice-to-have for us; it is the baseline.
We ship every lab grown diamond with an independent IGI report because you deserve to know exactly what you are getting, verified by a respected third party rather than taken on trust. It is the same reason we build only in solid, hallmarked metals and document our sourcing. Confidence should come standard, not as an upsell. Browse certified, ready-to-love designs in our lab grown diamond collection and engagement rings for women, or compare origins in our lab grown vs natural diamond guide.
IGI grades the full 4Cs and confirms the origin — your proof of quality.
What Certification Does to Price — The Money Angle
The lab you choose quietly shapes what you pay.
Certification is not just about trust; it affects the number on the tag. For the same stated grade, a GIA-certified diamond typically commands a premium of roughly 5 to 10 percent over an IGI-certified one. On a natural diamond, especially a larger stone, many buyers happily pay that for GIA's stricter grading and stronger resale recognition. On a lab grown diamond, though, that premium buys little functional benefit: the stone is still lab grown, the resale market is still developing, and your money is better spent lifting the color or clarity a notch on a reputable IGI report instead.
There is a subtler trap to avoid, too. A stone graded by a lenient or lesser-known lab can look like a bargain on paper while actually being a grade or two weaker than the report claims, so the apparent saving evaporates in real quality. The safe habit is simple: compare like-for-like on IGI or GIA reports, set a sensible quality floor, and verify online. Do that and certification becomes a tool that saves you money rather than a line item that costs you. See how grades translate to real numbers in our price guide, and weigh the overall decision in are lab grown diamonds worth it.
How to Read a Grading Report — In the Right Order
Whichever lab you choose, scan the report like this.
A grading report can look dense, but you only need a handful of lines. Start with the 4Cs: cut grade (prioritize Excellent or Ideal), then color, clarity, and carat. Next, confirm the origin line, which on a lab grown report states plainly that the stone is laboratory grown and often names the growth method, CVD or HPHT. Then note the report number and any laser inscription, a tiny serial etched on the stone's girdle that ties it to the certificate. Finally, glance at polish, symmetry, and measurements, which round out the quality picture.
For a lab grown diamond on an IGI report, a sensible quality floor is roughly VS clarity or better and G color or better, which reads bright and clean in a white metal setting. If you want to understand how those grades feed into cost, our lab grown diamond price guide connects the dots, and our overview of engagement rings puts it in the context of the whole ring.
What about AGS, EGL, and the rest?
You may encounter other labs. AGS was respected for detailed cut analysis and has been folded into GIA's operations. Be cautious with EGL and some lesser-known labs, which have a reputation for inflating grades by a level or two, so a "cheaper" stone on such a report may not be a real saving. In practice, for a lab grown diamond, a reputable IGI report is the reliable, best-value choice, and GIA remains the benchmark for natural stones. When in doubt, stick to IGI or GIA and always verify online.
Your Questions, Answered — IGI vs GIA
The certification questions buyers ask us most.
Every stone certified — every time
Every Aquamarise lab grown diamond ships with an independent IGI certificate and is set in solid gold or platinum, never plated. Handcrafted to order and backed by our lifetime warranty, so you always know exactly what you are getting.
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