Imagine two lab grown diamonds sitting side by side. They look identical. Same size, same sparkle, same price. But one comes with an IGI certificate, and one doesn't. Which should you buy?
The answer is always the certified one, and understanding why is the difference between buying a diamond with confidence and simply hoping you got what you paid for. A lab grown diamond's certificate is the only thing standing between you and an unverified stone graded by whoever happened to be selling it. This guide explains exactly what IGI certification proves, why it matters more than most buyers realize, how to read an IGI report line by line, and how IGI stacks up against GIA for lab grown diamonds.
The Problem Certification Solves
Here's something most people don't realize when they start shopping for a lab grown diamond: without independent certification, a diamond's quality is whatever the seller says it is.
Color, clarity, cut, carat weight - every one of these can be exaggerated. A stone a seller calls "G color, VS1 clarity" might actually be I color, SI2 clarity to an independent grader. And because these differences aren't always obvious to the naked eye, especially to someone who isn't a trained gemologist, an inflated grade can mean paying a premium price for a lower-quality stone. You'd never know.
This is the entire reason independent gemological certification exists. A certificate from a respected, independent lab is a neutral third party's verdict on exactly what the diamond is graded by experts with no stake in the sale, using standardized criteria and calibrated equipment. It takes the seller's word out of the equation entirely.
For lab grown diamonds specifically, this matters even more than it does for natural diamonds, because the lab grown market is newer, faster-moving, and less consistently regulated. A certificate is your protection. It's how you know the stone you're buying is genuinely what it's described to be and how you avoid overpaying for grades a stone doesn't actually earn.
What IGI is and Why It Dominates Lab Grown?
The International Gemological Institute, founded in 1975 and headquartered in Antwerp, is one of the world's largest independent gemological laboratories. And when it comes to lab grown diamonds specifically, IGI is the dominant certifying body, and it grades the large majority of lab grown diamonds sold worldwide.
This dominance isn't an accident. IGI moved early and decisively into lab grown diamond grading, building specialized expertise and processes for these stones at a time when the industry was just taking off. As a result, IGI became the standard that lab grown diamond sellers and buyers rely on. If you're shopping for a lab grown diamond, the odds are high that the stones you encounter will carry an IGI report.
At EthicStone, every lab grown diamond we sell comes with IGI certification. We chose IGI deliberately: it's the most widely trusted and widely used standard in the lab grown space, its grading is rigorous and consistent, and it gives our customers a certificate they can independently verify. When you buy from us, you're never taking our word for a diamond's quality; you're getting IGI's independent verdict, which you can check yourself.
To understand what those grades actually mean for how a diamond looks and what it's worth, our complete 4Cs of diamonds guide breaks down each grading factor in detail.
How to Read an IGI Lab Grown Diamond Report, Line by Line
An IGI certificate can look intimidating the first time you see one: a dense page of numbers, grades, and technical terms. But once you know what each part means, it becomes a straightforward, powerful tool for verifying your diamond. Here's what to look for, in the order it matters.
The Report Number
Every IGI report has a unique number, usually laser-inscribed on the diamond's girdle (the thin outer edge) as well. This is your verification key. You can enter it on IGI's official website to confirm the report is genuine and matches the stone. Always do this; it's the single most important check, and it takes thirty seconds. If a seller can't provide a report number you can verify, walk away.
The Description
"Laboratory Grown Diamond." The report will clearly state that the stone is a laboratory-grown diamond, and typically note the growth method — CVD (Chemical Vapor Deposition) or HPHT (High Pressure High Temperature). This confirms you're buying exactly what you think you are. A legitimate lab diamond report never hides that the stone is lab grown; it states it plainly.
Carat Weight
The exact weight of the stone, listed to two decimal places. This should match what the seller told you precisely. A stone described as "2 carat" should show a carat weight at or very near 2.00 on the report.
Color Grade
Graded on the same D-to-Z scale as natural diamonds, where D is completely colorless and the scale warms as it descends. For lab grown diamonds, you'll usually see grades in the D-to-J range. This is where seller exaggeration most often happens, so the certified grade is your reality check.
Clarity Grade
Rated from Flawless (FL) down through Internally Flawless (IF), Very Very Slightly Included (VVS1, VVS2), Very Slightly Included (VS1, VS2), Slightly Included (SI1, SI2), and Included (I1–I3). This tells you the extent of any internal inclusions. Eye-clean stones (typically VS and better, and many SI1s) show no inclusions visible to the naked eye.
Cut Grade
For round brilliant diamonds, IGI provides a cut grade from Excellent down to Poor, assessing how well the diamond's proportions return light. This is the factor that most affects a diamond's sparkle, so a high cut grade matters enormously. (Note that fancy shapes like ovals and cushions aren't given an official cut grade, since there's no single standard for their proportions.)
Polish and Symmetry
Two additional finish grades, also rated Excellent to Poor. Polish measures the smoothness of the diamond's surface; symmetry measures how precisely its facets align. Both Excellent is ideal, and these grades support the overall cut quality.
Measurements and Proportions
The report includes the stone's exact dimensions in millimeters and detailed proportion percentages (table, depth, and so on). For the technically minded, these numbers let you evaluate the cut in depth. For most buyers, the summary cut grade is enough.
Fluorescence
Whether the diamond glows under ultraviolet light, rated from None to Strong. This is usually a minor factor for lab grown diamonds and rarely affects appearance in normal lighting.
Once you've read a few IGI reports, the page stops being intimidating and starts being reassuring. Every grade the seller claimed is right there, independently verified, in black and white.
The One Check Almost Nobody Does (But Everybody Should)
Here's the step that separates confident buyers from hopeful ones: verify the report number on IGI's official website.
It sounds obvious, but a surprising number of people never do it. They see a certificate, assume it's legitimate, and buy. But a printed certificate is just paper; what matters is that the report is genuine and that it matches the stone in your hand.
The check is simple. Take the report number, go to IGI's official verification page, and enter it. The genuine report will come up, showing all the grades and details, which you can compare against both the physical certificate you were given and the laser inscription on the diamond's girdle. All three should match: the paper, the online record, and the inscription on the stone.
If they match, you have real confidence the diamond is exactly what it's supposed to be. If anything doesn't line up or if the number returns nothing, that's a serious red flag. This one thirty-second check is the most powerful protection available to a diamond buyer, and it's completely free.
IGI Vs GIA for Lab Grown Diamonds
Anyone researching diamond certification quickly runs into the two big names: IGI and GIA. Both are respected, independent gemological laboratories, and both grade lab grown diamonds. So how do they compare, and does the choice matter?
The Gemological Institute of America (GIA) is the older and, for natural diamonds, the more historically prestigious of the two. GIA created the 4Cs grading system that the entire industry uses, and for high-value natural diamonds, a GIA report is often considered the gold standard.
For lab grown diamonds, however, the picture is different. IGI grades the overwhelming majority of lab grown diamonds on the market and has been the specialist in this space since lab diamonds went mainstream. GIA entered lab grown grading more cautiously and later, and historically graded lab diamonds on a slightly different, less granular basis than it used for natural stones (though GIA's lab grown grading has evolved). The practical result is that IGI is simply far more common for lab grown diamonds, and its grading for these stones is detailed, consistent, and widely trusted.
For a lab grown diamond buyer, here's what actually matters: an IGI report for a lab grown diamond is a rigorous, reliable, independent grading that tells you exactly what you're getting. The fact that IGI dominates the lab grown space means IGI-certified stones are more available, and IGI's expertise with lab grown diamonds specifically is deep. A GIA-certified lab grown diamond is also perfectly good, but you'll encounter far more IGI reports, and for lab grown stones, IGI's grading is a trusted benchmark.
The key point is this: what matters most isn't IGI versus GIA, but it's that your lab grown diamond is certified by a respected, independent lab at all, versus not certified or "certified" only by the seller. Between IGI and GIA, both are legitimate. For lab grown diamonds specifically, IGI is the standard you'll most often see, and it's one you can trust.
What Certification Does Not Do
It's worth being clear about the limits of certification, because a certificate is powerful, but it isn't magic.
A certificate tells you what a diamond is and its measurable characteristics. It does not tell you whether a diamond is beautiful to your eye, whether it sparkles in a way you love, or whether it's the right stone for you. Two diamonds with identical certificates can still look slightly different in person, because grading captures measurable qualities, not the full subjective experience of a stone.
This is why certification and personal viewing work together. Use the certificate to verify the objective facts and protect yourself from overpaying. Then, wherever possible, view the actual stone or its high-quality video to judge the things a certificate can't capture, like how it catches the light, how the sparkle looks to you, whether any inclusions (even in a good clarity grade) happen to sit in a distracting spot. A certificate is the foundation of a confident purchase. Your own eyes complete it.
Certification exists to protect you. Without it, a lab grown diamond's quality is just the seller's claim; with it, you have an independent expert's verified verdict on exactly what you're buying. For lab grown diamonds, IGI is the dominant, trusted standard and it grades the majority of lab diamonds worldwide; its reports are rigorous and reliable.
When you buy a certified stone, read the report (especially the color, clarity, and cut grades), and above all, verify the report number on IGI's official website so you know the certificate is genuine and matches the stone. That single free check is your strongest protection.
At EthicStone, every lab grown diamond comes with IGI certification precisely because we believe you should never have to take our word for a diamond's quality, and you should have independent proof. Explore our lab grown diamonds to learn more, or browse our lab grown diamond engagement rings every one backed by IGI certification you can verify yourself.
Frequently Asked Questions
⮞ What is an IGI certified lab grown diamond?
An IGI certified lab grown diamond has been independently graded by the International Gemological Institute, which documents its exact carat weight, color, clarity, cut, and other characteristics on a verifiable report. The certification is independent proof of the diamond's quality, rather than relying on the seller's claims.
⮞ Is IGI certification good for lab grown diamonds?
Yes. IGI is the dominant and most trusted certifying body for lab grown diamonds, grading the majority of lab diamonds sold worldwide. Its grading is rigorous, consistent, and independent, and IGI has specialized expertise in lab grown diamonds specifically, making an IGI report a reliable benchmark for these stones.
⮞ Is IGI or GIA better for lab grown diamonds?
Both are respected independent labs. GIA is historically more prestigious for natural diamonds, but IGI dominates lab grown diamond grading and is the standard you'll most often encounter for lab diamonds. For lab grown stones, an IGI report is rigorous and widely trusted. What matters most is that the diamond is certified by a respected independent lab at all.
⮞ How do I verify an IGI certificate?
Take the report number from the certificate (also laser-inscribed on the diamond's girdle) and enter it on IGI's official verification website. The genuine report will appear, and you can confirm it matches both the physical certificate and the inscription on the stone. This free check is the most important step in verifying a diamond.
⮞ What should an IGI report tell me?
An IGI report documents the diamond's report number, confirmation that it's laboratory-grown and its growth method, carat weight, color grade, clarity grade, cut grade (for round diamonds), polish, symmetry, measurements, and fluorescence. Together, these give you a complete, independent picture of exactly what the diamond is.
⮞ Do all lab grown diamonds come with certification?
They should, but not all do. A reputable seller always provides independent certification, most commonly from IGI. If a lab grown diamond has no independent certificate, or only a seller's own grading, you have no verified proof of its quality, which is a strong reason to be cautious and to choose a certified stone instead.
⮞ Does an IGI certificate guarantee a diamond is beautiful?
No. A certificate verifies a diamond's measurable characteristics, but not the subjective experience of how it looks to you. Two diamonds with identical certificates can look slightly different in person. Use the certificate to verify the facts and protect against overpaying, then view the actual stone to judge its beauty.