A diamond certificate, more correctly called a grading report, is an independent laboratory's description of a stone. It does not set a price and it is not a guarantee. What it does is let you check that the stone in front of you is what the seller says it is. The lab behind that report matters, so here is a fair look at the two names you will meet most often in India, and at the two others you are likely to see.
IGI vs GIA: what is the difference?
Both are established independent laboratories. The differences are in history, structure and the kind of report each is best known for.
GIA (Gemological Institute of America) was established in 1931 and is a public benefit, nonprofit institute, according to GIA's own history. It created the 4Cs and the International Diamond Grading System, which is why its D-to-Z colour and FL-to-I3 clarity scales are the reference other labs work from. GIA India has run a grading laboratory in Mumbai since 2008 and opened a Surat branch in 2018.
IGI (International Gemological Institute) describes itself as a grading and certification provider since 1975 and one of the largest independent grading organisations, with laboratories and schools in 10 countries. It grades natural diamonds, lab-grown diamonds, coloured stones and finished jewellery, and states that it holds ISO 17025 accreditation for both natural and lab-grown diamond grading. IGI says it pioneered grading reports for finished jewellery.
| GIA | IGI | |
|---|---|---|
| Founded | 1931 | 1975 |
| Structure | Nonprofit institute | Independent commercial laboratory group |
| Known for | Creating the 4Cs; reference lab for natural diamonds | Lab-grown and finished jewellery reports |
| Lab-grown reports | Premium or Standard classification since 1 October 2025 | Full grading reports for lab-grown stones |
| Jewellery reports | Focus is loose stones | Yes, for finished pieces |
| Global reach | Laboratories on several continents, including Mumbai | Laboratories in 10 countries |
| Online verification | GIA Report Check | IGI Verify Your Report |
Is GIA stricter than IGI?
This is the most repeated claim in comparisons, and it deserves care. In the trade, GIA is widely perceived as the benchmark for natural diamond grading, and many retailers write that a GIA colour or clarity grade is more conservative than the same grade from other labs. That perception affects how natural stones are priced and resold.
We looked for an independent, published study that measures grading differences between the two labs and did not find one. The claims we found came from retailers, some of whom sell stones graded by one lab or the other. So treat "stricter" and "looser" as market perception, not an established fact. What is established is that both labs publish their reports for online verification, and that both separate natural from laboratory-grown stones on the report.
The practical upshot: for a high-value natural diamond, many buyers and resellers prefer a GIA report because it is the reference the market is used to. For a lab-grown diamond, the answer is different, as the next section explains.
IGI vs GIA for lab-grown diamonds
The two labs now take different approaches to lab-grown stones, and that is the single biggest difference for a buyer today.
- GIA: since 1 October 2025, GIA's laboratory-grown service no longer gives specific colour and clarity grades. According to GIA's published criteria, a stone is classified as Premium (D colour, VVS clarity, Excellent polish and symmetry, and Excellent cut for round brilliants) or Standard (E to J colour, VS clarity, Very Good polish, and Very Good symmetry and cut for rounds, or Very Good or Good symmetry for fancy shapes). A stone with any criterion outside both sets does not receive a GIA assessment. The service covers loose, colourless to near-colourless stones of 0.15 carat and up, and every assessed stone's girdle is laser inscribed with "Laboratory-Grown" and its GIA assessment number.
- IGI: issues lab-grown diamond reports that grade the 4Cs, and its reports state natural or lab-grown origin.
If you want to compare two lab-grown stones grade by grade, a report that gives specific grades is more useful. If you simply want an independent confirmation that a lab-grown stone meets a quality threshold, GIA's classification does that.
Where do SGL and HRD fit in?
Both are independent laboratories you will see on stones sold in India.
| Lab | Background | What it grades | Notes for Indian buyers |
|---|---|---|---|
| GIA | Nonprofit, founded 1931, United States | Natural and lab-grown diamonds, coloured stones | Mumbai laboratory since 2008, Surat branch since 2018 |
| IGI | Founded 1975, independent | Natural and lab-grown diamonds, coloured stones, jewellery | Issues reports for finished jewellery as well as loose stones |
| SGL | Founded 2007 in London | Natural and lab-grown (CVD and HPHT) diamonds, jewellery, coloured stones | Experience centres in Mumbai, Surat, Jaipur and Hyderabad |
| HRD Antwerp | Antwerp, active since 1973 | Natural and lab-grown diamonds, coloured diamonds, jewellery | Also issues lab-grown jewellery reports |
The details above come from each laboratory's own website: SGL and HRD Antwerp describe their services and report types there. None of these labs is a government body. At a November 2024 consultation, the Central Consumer Protection Authority discussed proposals for accreditation systems to regulate diamond testing laboratories, alongside clearer labelling of natural and lab-grown stones.
Can small diamonds in men's jewellery be certified?
Rarely, one by one. Most men's diamond pieces use rows or clusters of small stones, called melee or pavé, weighing a few points each. Grading each of them individually would cost more than the stones, so they are bought in parcels sorted to a colour and clarity range and do not carry their own reports.
What you can reasonably ask for instead:
- A written description on the invoice: total carat weight, colour and clarity range, and whether the stones are natural or laboratory-grown.
- A jewellery report: labs such as IGI, SGL and HRD Antwerp grade finished pieces, describing the stones and metal as set.
- An individual report for any centre stone large enough to justify one, with its inscription.
Our guide to the 4Cs of diamonds explains what colour and clarity ranges mean in a band.
How to verify an IGI or GIA report
Verify every report before you pay. The steps are the same for any major lab:
- Find the report number on the paper or digital report.
- Enter it on the lab's own website: GIA Report Check or IGI's Verify Your Report page. Type the address yourself rather than following a link or QR code supplied by a seller.
- Compare the online record with the paper: shape, measurements to two decimal places, carat weight and grades.
- Look at the girdle with a 10x loupe for the laser inscription and match the number.
- Confirm the report says natural or laboratory-grown, and that this matches the invoice.
The field-by-field walkthrough is in our guide on how to read a diamond certificate, and our note on whether it is safe to buy jewellery online covers the wider checks for an online purchase.
Which report should you ask for?
Match the report to the purchase. A lab name is only useful if the report type fits what you are buying.
| What you are buying | Report worth asking for | What it should confirm |
|---|---|---|
| Natural solitaire, about half a carat or more | Full grading report from an independent lab; many buyers prefer GIA here | 4Cs, measurements, natural origin, inscription |
| Lab-grown solitaire | GIA assessment or a lab-grown report with specific grades, such as IGI's | Laboratory-grown origin, quality, inscription |
| Pavé band, eternity ring or bracelet | Written invoice description, or a jewellery report | Total carat weight, colour and clarity range, origin, metal |
| Black diamond piece | Invoice description; a colour origin report for a large stone | Whether the colour is natural or treated |
Whatever the report, it describes the stone on the day it was graded. If a piece is later reset, resized or repaired, ask the jeweller to confirm the stone was not swapped, which the inscription makes easy to check.
Red flags to watch for
- An in-house "certificate" printed by the seller rather than an independent lab.
- A lab you cannot verify online, or a report number that returns nothing.
- Mismatched measurements between the report and the stone.
- "Diamond" with no origin stated on a stone that is actually laboratory-grown. Under Indian standards, the word diamond on its own is reserved for natural diamonds.
How AXIOM approaches this
AXIOM makes its pieces at the Bharat Diamond Bourse in Mumbai. For AXIOM diamond pieces, certification details are available on request: contact us with the piece you have in mind, and our about page describes how the pieces are made.
The practical takeaway
Trust independent reports you can verify, and read what they say rather than which logo they carry. For a large natural stone, a GIA report is the reference the market knows best. For a lab-grown stone, decide whether you want exact grades or a quality classification. For a pavé band, ask for the description in writing.
