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IGI and SGL are both independent gemological laboratories that grade diamonds and issue certificates. IGI, the International Gemological Institute, is the most widely used laboratory for lab grown diamonds worldwide and is recognised internationally. SGL, Solitaire Gemological Laboratories, is an Indian laboratory whose reports are widely accepted within India but carry less recognition outside it. Both grade on the same 4C framework. The practical difference is recognition, not honesty.
What does a diamond certificate actually tell you?
A certificate is an independent record of what a stone is. For a lab grown diamond it should state:
- Carat weight, measured not estimated
- Colour grade, on the D to Z scale
- Clarity grade, from FL through to I
- Cut grade, which for round stones is the single biggest factor in how it looks
- Growth method, CVD or HPHT
- Any post-growth treatment applied to improve colour
- The report number, which should be laser-inscribed on the girdle of the stone
That last point is the one most buyers miss. The inscription is what ties the paper to the stone in your hand. A certificate with no matching inscription proves very little.
What is IGI?
The International Gemological Institute was founded in Antwerp in 1975 and has laboratories across the world, including in India. It grades both mined and lab grown diamonds and has become the default laboratory for lab grown stones internationally.
For a buyer, the relevant consequence is portability. An IGI report is understood by jewellers, insurers and valuers outside India as readily as within it.
What is SGL?
Solitaire Gemological Laboratories is an Indian gemological laboratory that grades diamonds, coloured stones and jewellery. SGL reports are widely used and accepted across the Indian trade.
SGL grading is carried out on the same 4C framework as any other laboratory. What differs is international recognition: outside India, an SGL report is less familiar to valuers and insurers than an IGI one.
Is IGI better than SGL?
Not in the sense of being more honest. Both are independent third parties with a commercial interest in being accurate, since a laboratory whose grades cannot be trusted has no business.
IGI is better in one specific and practical sense: it travels. If there is any chance the piece will be valued, insured, resold or inherited outside India, an IGI report will be understood without explanation. An SGL report may need one.
There is also a wider point about grading in general. Laboratories vary slightly in strictness, and a stone graded VS1 by one lab might be VS2 at another. This is true across the whole industry and is not specific to either of these two. It is a reason to compare stones in person rather than to compare certificates on a screen.
When does the difference actually matter?
| Situation | Does it matter? |
|---|---|
| Daily wear jewellery under 1 carat | Very little. Either is fine. |
| An engagement ring you plan to keep | Some. IGI is the safer default. |
| A high-value piece, 2 carats or more | Yes. Ask for IGI. |
| You may move abroad, or insure internationally | Yes. IGI travels; SGL may not. |
| Buying to resell | Reconsider. Neither certificate makes lab grown diamonds a good resale asset. |
Does certification affect buyback value?
Yes, though not in the way most people assume. The certificate does not change what a stone is worth. It changes whether the value can be established without argument.
It also has a direct cost if you lose it. At Ivana Jewels, replacing a misplaced certificate at the time of buyback or exchange costs ₹2,000 per carat for IGI and ₹1,000 per carat for SGL. On a 2 carat stone that is ₹4,000 or ₹2,000 respectively, which is a straightforward argument for keeping the paperwork somewhere sensible.
Our lifetime buyback returns 80% of the prevailing diamond value and 100% of the prevailing gold value at the time of buyback, with making charges, discounts and GST deducted. Full terms are on our All Policies page.
How to verify a certificate is genuine
Do not take the printed report at face value. Both laboratories publish online verification.
- Find the report number on the certificate.
- Look for the same number laser-inscribed on the girdle of the stone. A jeweller's loupe will show it; ask them to point it out.
- Enter the report number on the issuing laboratory's own website and check the grades match the printed report.
If the inscription does not match the paper, or the number does not appear in the laboratory's database, stop there.
What to be sceptical about
- “Certified” without naming the laboratory. Ask which one. An unnamed certificate is not a certificate.
- In-house certificates. A report issued by the seller is not independent, whatever it is called.
- Certification only above a carat threshold. Some retailers certify only larger stones. Ask whether your specific piece is certified.
- A certificate with no inscription on the stone. Common on smaller stones, but it means the paper cannot be tied to that specific diamond.
What Ivana Jewels does
Every lab grown diamond we sell is certified by IGI or SGL, and the certificate is supplied with the piece. Gold is BIS hallmarked in 14kt or 18kt. If you have a preference for IGI specifically, say so when ordering and we will tell you what is available.
Frequently asked questions
Is an SGL certified diamond real?
Yes. SGL grades genuine diamonds on the same 4C framework as any other laboratory. The difference is international recognition, not authenticity.
Can I get a diamond re-certified by a different laboratory?
Yes, though it means unsetting the stone, submitting it, and paying the grading fee. It is occasionally worth doing for a high-value stone being insured abroad. For most jewellery it is not.
Does GIA certify lab grown diamonds?
GIA does issue reports for lab grown diamonds. It is more commonly associated with mined stones, and IGI dominates the lab grown market. Ivana Jewels uses IGI and SGL.
What happens if I lose my certificate?
Keep it. At the time of buyback or exchange, replacing a lost certificate costs ₹2,000 per carat for IGI and ₹1,000 per carat for SGL. Photograph it and store the image somewhere you will find it.
Should the certificate number be on the diamond itself?
On stones above roughly half a carat, yes, laser-inscribed on the girdle. It is invisible to the naked eye and readable under a loupe. Ask to see it before you pay.
Browse lab grown diamond rings and solitaire rings, or bring a certificate to any of our eleven showrooms and we will walk you through it, open 10:30am to 9pm every day.
