IGI vs GIA Certificates: Which to Trust for Lab-Grown Diamonds
For IGI vs GIA on lab-grown diamonds, the short version is this: both are real, independent grading labs, but as of late 2025 they report lab-grown stones very differently, and that difference is exactly what trips up shoppers. At Vanhess Jewellery in Coquitlam, BC, we only sell certified stones, and the certificate question comes up at the counter almost every day now that lab-grown is so common. Here is what each lab does and how to read what you get.
A diamond certificate (the trade calls it a report, not a certificate, but everyone says certificate) is an independent lab's assessment of a stone. It is not an appraisal and not a price. It tells you what the diamond is, so you are not taking the seller's word for it.
IGI: the volume leader for lab-grown
The International Gemological Institute (IGI) grades the large majority of lab-grown diamonds on the market today. If you shop for a lab-grown engagement ring, the stone most likely comes with an IGI report. IGI grades lab-grown diamonds on the same familiar scales it uses for natural stones: the 4Cs, meaning a specific cut grade, a colour grade on the D-to-Z scale, a clarity grade from Flawless down, and an exact carat weight.
That is the practical advantage of an IGI lab-grown report right now: it still gives you the granular D-colour, VVS-clarity numbers that most buyers expect and that make it easy to compare one stone against another.
GIA: the same lab that set the natural-diamond standard, with a new lab-grown system
The Gemological Institute of America (GIA) is the lab that created the 4Cs and the D-to-Z colour scale, and its natural-diamond reports are the gold standard. GIA grades lab-grown diamonds too, but how it reports them has changed twice, and the latest change matters.
From 2020, GIA reported lab-grown stones using the same specific colour and clarity grades as natural diamonds. Then, effective October 1, 2025, GIA replaced that with a new Laboratory-Grown Diamond Quality Assessment that sorts stones into two categories, "Premium" and "Standard," rather than issuing a single D-to-Z colour grade and a specific clarity grade. GIA explained that since 2022 about 95% of submitted lab-grown diamonds fell into a very narrow colour range and 98% into a narrow clarity range, so the fine natural-diamond nomenclature no longer told buyers much.
Under the new GIA system, a "Premium" lab-grown diamond must hit D colour, VVS clarity or better, excellent polish and symmetry, and (for round brilliants) an excellent cut. "Standard" covers a defined range below that, and stones that miss the minimums get no assessment at all.
IGI vs GIA for lab-grown, side by side
| IGI | GIA | |
|---|---|---|
| Share of lab-grown reports | The large majority | Smaller, but the original 4Cs authority |
| How it reports colour & clarity | Specific 4Cs grades (D-to-Z, Flawless down) | "Premium" or "Standard" categories since Oct 1, 2025 |
| Cut grade | Yes, for standard shapes | Factored into Premium/Standard |
| Laser inscription | Yes, report number on the girdle | Yes, report number on the girdle |
| Easy stone-to-stone comparison | Yes, granular grades | Less granular now (two tiers) |
So which should you trust? Both. They are both legitimate, independent labs. For lab-grown specifically, an IGI report gives you the detailed numbers most people want for comparison shopping, and it is what the vast majority of lab-grown stones carry. A GIA report carries the name that set the whole grading standard, but for lab-grown its new two-tier system tells you less about the exact colour and clarity than an IGI report does. Neither is "fake." They just answer the question at different resolutions now.
How to read a lab report
Whatever lab issued it, look for the same things. Confirm the report says laboratory-grown or lab-grown clearly, so there is no ambiguity about origin. Check the carat weight, the shape, and the measurements in millimetres. On an IGI report, read the cut, colour, and clarity grades. On a current GIA lab-grown assessment, read the Premium or Standard designation plus the polish, symmetry, and cut notes.
Then find the report number and match it to the laser inscription on the diamond itself.
Laser inscription: the link between paper and stone
Both IGI and GIA laser-inscribe the report number onto the diamond's girdle, the thin edge around its widest point. The inscription is microscopic and does not affect the stone, but under magnification it lets you confirm that the certificate in your hand belongs to the diamond in front of you, not a different stone. We check the inscription against the report under a loupe in the shop, and you should ask any seller to do the same. A report with no matching inscription is just a piece of paper.
Why a certificate matters at all
A certificate protects you from paying natural-diamond money for a lab-grown stone, or top-grade money for a lower grade. It gives an independent description you can compare and insure against. We sell only certified stones at Vanhess, lab-grown and natural, because without a report you are trusting a description with nothing behind it. For a purchase this size, that is not a corner worth cutting.
Key Takeaways
- Both IGI and GIA are legitimate independent labs; the difference is how they now report lab-grown stones.
- IGI grades the large majority of lab-grown diamonds and still uses specific 4Cs grades (D-to-Z colour, exact clarity).
- Since October 1, 2025, GIA reports lab-grown diamonds as "Premium" or "Standard" rather than single colour and clarity grades.
- Both labs laser-inscribe the report number on the girdle; always match it to the report under magnification.
- A certificate is an independent description, not an appraisal or a price. Buy certified.
Frequently Asked Questions
Is IGI or GIA better for lab-grown diamonds?
Neither is "better"; they report differently. IGI grades the large majority of lab-grown stones and still gives specific 4Cs grades, which makes comparison easy. GIA, the lab that created the 4Cs, now sorts lab-grown diamonds into "Premium" and "Standard" categories as of October 2025, which is less granular. For detailed comparison shopping, IGI's report is the more useful.
Does GIA still grade lab-grown diamond colour and clarity?
Not as individual D-to-Z colour and specific clarity grades. Effective October 1, 2025, GIA replaced that with a Laboratory-Grown Diamond Quality Assessment that classifies stones as "Premium" or "Standard." GIA made the change because almost all submitted lab-grown diamonds clustered in a very narrow quality range.
Why does a lab-grown diamond need a certificate?
A certificate is an independent lab's description of the stone, confirming it is lab-grown and recording its weight, cut, colour, and clarity. It protects you from misrepresentation, lets you compare stones fairly, and supports insurance. At Vanhess we sell only certified diamonds.
What is a laser inscription on a diamond?
A laser inscription is the report number etched microscopically onto the diamond's girdle by the grading lab. It does not affect the stone and lets you confirm under magnification that the certificate matches the actual diamond. Both IGI and GIA inscribe their reports.
Sources
- National Jeweler — GIA's New Quality Assessment for Lab-Grown Diamonds (2025)
- GIA — The 4Cs of Diamond Quality (accessed June 2026)
- IGI — Lab Grown Diamond Report (accessed June 2026)
Data sourced June 2026. If you spot something out of date, let us know and we will update the guide.
Visit Vanhess
We sell only certified diamonds at our Coquitlam shop, lab-grown and natural, and we will read the report and check the laser inscription against the stone with you under the loupe. Come compare certified stones in person and browse our engagement rings or our rings while you are here. Find us at 2929 Barnet Highway, Unit 2424, Coquitlam BC, or call +1 (604) 653-6449.
