GIA vs IGI
GIA and IGI both issue reports for natural and laboratory-grown diamonds, and both let you check a report number on their own websites. The main difference today is on laboratory-grown stones: GIA reports issued from 1 October 2025 give a Premium or Standard assessment instead of colour and clarity grades, and the two labs inscribe laboratory-grown girdles differently.
Last reviewed: 18 October 2026
Reviewed by the Superior Gems team
How do GIA and IGI compare?
| Point | GIA | IGI |
|---|---|---|
| Full name | Gemological Institute of America | International Gemological Institute |
| Founded | 1931; independent nonprofit lab | 1975, in Antwerp |
| Natural diamond reports | Yes; give the 4Cs | Yes |
| Laboratory-grown reports | From 1 October 2025, a Premium or Standard assessment instead of colour and clarity grades; earlier reports stay valid and keep their grades | Yes; the report states the stone is laboratory-grown; colour, clarity and cut are graded, and the growth method is noted |
| Laboratory-grown girdle inscription | Laboratory-Grown plus the report number | Starts with LG, then the report number |
| Online check | GIA Report Check ↗ | IGI Verify your report ↗ |
Lab descriptions are the labs' own. Names belong to their owners; no endorsement implied.
What do both reports record?
Every report carries a report number, the shape and the carat weight; match all three to the stone. Natural diamond reports also record measurements, colour, clarity, cut (for round stones), polish, symmetry and fluorescence.
An online lookup confirms the report is genuine in the lab's records. It does not prove the stone in your hand is the one in the report. Only the girdle inscription does.
What changed for GIA laboratory-grown reports?
From 1 October 2025, GIA gives laboratory-grown diamonds a Premium or Standard assessment instead of colour and clarity grades. GIA laboratory-grown reports issued before that date stay valid and keep their colour and clarity grades.
So two GIA reports for similar laboratory-grown stones can look different depending on when they were issued. Check the issue date on the report.
How do I check a laboratory-grown inscription?
Look at the girdle under 10x magnification. A GIA laboratory-grown girdle reads Laboratory-Grown plus the report number. An IGI laboratory-grown inscription starts with LG, so include the prefix when you enter the number on IGI's site.
Where does HRD fit?
HRD Antwerp is the third lab in our listings. Its reports confirm whether a stone is natural, laboratory-grown or treated, and cover carat, colour, clarity and cut. In our listings, HRD reports appear on natural stones. Look up an HRD certificate number on HRD's portal ↗.
Which report should I ask for?
We don't rank labs. Grading reports are issued by independent laboratories, we supply them as issued, and we are not responsible for a lab's opinion or for differences between labs. Ask for the report your own customers expect, and check it on the lab's site.
In the trade portal you can filter by lab. Natural certified diamonds carry GIA, IGI or HRD reports; laboratory-grown diamonds carry IGI or GIA reports where available.
Questions
Is GIA better than IGI?
We don't rank labs. Both are independent laboratories whose reports we supply as issued, and you can check either report on the lab's own website.
Are GIA laboratory-grown reports from before 1 October 2025 still valid?
Yes. Earlier GIA laboratory-grown reports stay valid and keep their colour and clarity grades.
How do I check an IGI laboratory-grown report?
Enter the report number on IGI's Verify your report page, including the LG prefix, then match the girdle inscription to the report.
Does every diamond we list have a GIA or IGI report?
No. Melee and cut-to-spec stones are graded in-house and sold without a lab report, and they are labelled that way in our listings.
Not listed? Ask us
Call our Sydney office: +61 410 058 909