IGI vs GIA: which diamond certificate should you trust?
A certificate is what turns a diamond's specs from a sales claim into a verifiable fact. Without one, you are trusting the seller. With one, you are trusting an independent lab.
- A certificate grades, it does not appraise. It documents the 4Cs, not what the stone is worth.
- IGI is the most widely used lab for lab-grown diamonds, with a huge global grading network.
- GIA is the historic standard-setter and grades both mined and lab-grown stones.
- Check the inscription. The certificate number should be laser-inscribed on the stone's girdle and match the report.
Here is how the two labs you will see most — IGI and GIA — compare, and how to actually read the report.
What a diamond certificate actually is
A grading report — often called a certificate — is an independent lab's measurement of a specific stone's carat, color, clarity, cut and finish. It is not a valuation, and it does not tell you what to pay.
What it does is make the stone's quality verifiable. When a seller claims "VS1, F color, Excellent cut", the report either backs that up or it does not.
IGI vs GIA: how they differ
| IGI | GIA | |
|---|---|---|
| Full name | International Gemological Institute | Gemological Institute of America |
| Founded | 1975 | 1931 |
| Strength | Largest global network; leading lab for lab-grown | Historic standard-setter; premium recognition |
| Grades lab-grown | Yes — primary focus | Yes (with laboratory-grown reports) |
| Report depth | Full 4Cs + photos | Full 4Cs |
How to read a grading report
- Carat weight — the stone's weight to two decimals.
- Color grade — D (colorless) through Z.
- Clarity grade — FL/IF, VVS, VS, SI, I, with a plot of inclusions.
- Cut grade — how well the stone is proportioned (Excellent is best).
- Measurements & proportions — table %, depth %, and angles.
- Polish & symmetry — surface finish quality.
- Fluorescence — how the stone reacts to UV light.
The laser inscription: your proof of match
Reputable sellers laser-inscribe the certificate number on the stone's girdle (the thin outer edge). Under a loupe, that number should match the report in front of you. It is how you know the paper and the stone belong together.
Every Everlum stone over 0.5 ct carries this inscription, so its origin and specs are documented and verifiable — no guesswork.
Why this matters when you buy
Because it lets you buy confidently at a distance — which matters even more online. If a listing has no certificate, or the specs do not match the report, walk away.
Browse certified stones in our loose diamond search, or message us with any report and we will help you read it.
Frequently asked questions
Is IGI as good as GIA?
Both are reputable, independent labs. GIA is the historic standard-setter and carries premium recognition; IGI has the largest global network and is the leading certifier of lab-grown diamonds.
Does a certificate tell me what a diamond is worth?
No. A certificate documents the 4Cs — quality — not price. Valuation is a separate appraisal, and market price depends on many factors.
What should I check on a diamond certificate?
The carat, color, clarity and cut grades, plus the measurements and the certificate number. Confirm that number is laser-inscribed on the stone itself.
Are lab-grown diamonds certified the same way as mined?
Yes. IGI and GIA grade both types using the same 4Cs standards; lab-grown reports simply state that the stone was grown in a laboratory.
Ready to see real stones?
Browse certified lab-grown diamonds by shape, carat and quality — or message us and a human will help you choose.