When you buy a lab-grown diamond in India, one question matters more than any other.
Does it have an IGI certificate?
Not because the certificate makes the diamond real. The diamond is real regardless. But because the certificate tells you exactly what you are getting, cut, clarity, colour, carat, and growth method, verified by an independent laboratory that has no financial interest in making the stone look better than it is.
Without a certificate, you are trusting the seller's word. With one, you have evidence.
This guide explains what an IGI certificate actually contains, how to read it, how to verify it, and why it is non-negotiable when buying a lab-grown diamond in India.
What Is IGI and Why Does It Matter?
The International Gemological Institute was founded in Antwerp in 1975. It is today one of the largest independent gem grading organisations in the world, with laboratories across Belgium, India, the USA, Hong Kong, Japan, and several other countries.
IGI has offices in Mumbai and other Indian cities, which makes it particularly relevant for the Indian market. A significant volume of lab-grown diamonds sold in India are graded by IGI, and the institute has specifically developed grading standards for lab-grown stones.
Unlike a jeweller's in-house quality claim, IGI has no stake in selling you the diamond. Its job is purely to assess and report.
What Does an IGI Certificate Actually Contain?
An IGI grading report for a lab-grown diamond covers the following:
Report Number
Every IGI certificate carries a unique report number laser-inscribed on the girdle of the diamond itself. This number links the physical stone to its digital record on the IGI website.
Shape and Cutting Style
The report describes the diamond's shape, for example Round Brilliant, Oval, Princess, Cushion, and its cutting style.
Measurements
The diamond's exact dimensions in millimetres, including diameter, depth, and table size.
Carat Weight
The precise weight of the stone to two decimal places. One carat equals 0.2 grams.
Colour Grade
IGI uses the same D-to-Z colour scale used for mined diamonds. D is colourless and the highest grade. Z carries visible yellow or brown tint. For lab-grown diamonds, colourless and near-colourless grades (D to J) are the most common and desirable range.
Clarity Grade
Clarity describes the presence, size, and location of inclusions inside the diamond. The scale runs from Flawless (FL) at the top to Included (I3) at the bottom. Most commercially sold lab-grown diamonds fall in the VS1 to SI1 range.
Cut Grade
Cut is widely considered the most important of the 4Cs because it determines how well the diamond handles light. IGI grades cut as Excellent, Very Good, Good, Fair, or Poor. Always aim for Excellent or Very Good.
Polish and Symmetry
These describe the quality of the diamond's surface finish and the precision of its facet arrangement. Both follow the same Excellent to Poor scale.
Fluorescence
Some diamonds glow faintly under ultraviolet light. IGI notes whether a stone has None, Faint, Medium, Strong, or Very Strong fluorescence. This does not affect quality but can affect appearance in certain lighting.
Growth Method
For lab-grown diamonds, the certificate states whether the stone was produced by CVD or HPHT. This is informational and does not affect the grade.
Comments
Any notable characteristics are listed here, including HPHT treatment for colour, if applicable.
How to Verify an IGI Certificate
This step is important and takes less than a minute.
Go to the IGI website and enter the report number from the certificate. The full grading report for that specific diamond will appear on screen. Compare it with the physical certificate you were given.
If the details match, you have a verified stone. If the seller cannot provide a certificate, or if the report number does not appear in the IGI database, that is a serious red flag.
Every lab-grown diamond sold by Goenka Jewellers comes with a verifiable IGI certificate. The report number is laser-inscribed on the stone itself.
IGI vs GIA vs SGL: Which Certification Should You Trust?
This question comes up often in India.
IGI is the most widely used certification for lab-grown diamonds globally and in India. Its grading standards for lab-grown stones are well-established, and its Indian presence makes it highly accessible.
GIA (Gemological Institute of America) is widely considered the gold standard for mined diamond certification. GIA also certifies lab-grown diamonds, though its reports for lab-grown stones use a slightly different format. GIA-certified lab diamonds are excellent but slightly less common in the Indian retail market.
SGL (Solitaire Gemological Laboratories) is an India-based certification body. It is recognised domestically but carries less international weight than IGI or GIA. Some budget-segment lab diamonds in India come with SGL certificates.
For most Indian buyers purchasing lab-grown diamond jewellery, an IGI certificate from a reputable retailer is the right benchmark. It is internationally recognised, easy to verify, and specifically designed for lab-grown stones.
What India's BIS Standard Says About Certification
India's Bureau of Indian Standards released IS 19469:2025 to define and regulate lab-grown diamonds in the Indian market. The standard requires that lab-grown diamonds be clearly identified and disclosed as such at the point of sale.
This means that any retailer selling a lab-grown diamond in India without proper disclosure is operating outside the standard. A certified IGI report satisfies this disclosure requirement because it explicitly states the diamond's lab-grown origin and growth method.
When you buy an IGI-certified lab-grown diamond from a compliant retailer, you are protected under both IGI's own standards and India's national framework.
What to Check on an IGI Certificate Before You Buy
Run through this checklist before finalising any purchase:
Report number
Does the number on the certificate match the one laser-inscribed on the diamond's girdle?
Growth method
Is it listed as CVD or HPHT? Either is fine, but it should be stated.
Cut grade
Is it Excellent or Very Good? Avoid Good or below for jewellery.
Colour and clarity
Do these match what the seller described to you?
Verification
Have you checked the report number on the IGI website yourself, not just taken the seller's word?
Retailer reputation
Is the seller a certified retailer with a clear buyback and return policy?
If all five check out, you are in a good position to buy with confidence.
Frequently Asked Questions
Is an IGI certificate the same as a hallmark?
No. A hallmark certifies the metal purity of the jewellery, for example 18K or 14K gold. An IGI certificate grades the diamond itself. Both matter, but they certify different things.
Can an IGI certificate be faked?
The certificate document can be duplicated fraudulently, which is exactly why you should always verify the report number on the IGI website directly. The laser inscription on the diamond girdle adds a physical layer of verification.
Does IGI certification affect the resale value of a lab-grown diamond?
Yes. An IGI-certified diamond is easier to resell because the buyer has an independent quality record to rely on. Uncertified diamonds are harder to price and sell.
Is an SGL certificate acceptable for lab-grown diamonds in India?
SGL is a recognised Indian body, but IGI or GIA certification carries more weight for resale and international recognition. For high-value purchases, always prefer IGI or GIA.
What does it mean if the IGI report says HPHT treatment?
It means the diamond was treated using the High Pressure High Temperature process to improve or alter its colour. This is an accepted and disclosed industry practice. It does not make the diamond less real, but it should be reflected in the price.
Do all Goenka Jewellers diamonds come with IGI certificates?
Yes. Every lab-grown diamond in the Goenka Jewellers collection is IGI-certified. The certificate is provided with every purchase.
The Bottom Line
A lab-grown diamond without a certificate is like a product without a label. You are guessing at what you have.
An IGI certificate removes the guesswork. It tells you the cut, the clarity, the colour, the carat weight, the growth method, and the exact report number to verify it all. It is the single most important document in any lab-grown diamond purchase.
Before you buy, ask for the certificate. Verify the number. Then buy with confidence.
To understand more about lab-grown diamonds before you purchase, read our guide on Are Lab-Grown Diamonds Real? 10 Myths Busted by Goenka Jewellers. Or explore Goenka Jewellers' certified lab-grown diamond collection and shop with full documentation.