An IGI certificate is not a formality. It is a grading report produced by an independent laboratory that examined your diamond under controlled conditions and documented what it found. When you buy an IGI-certified lab-grown diamond in India, you know precisely what you are buying — not what the seller says you are buying. This guide explains what each section of the certificate means, why it matters specifically for lab-grown diamonds, and how to use the certificate to verify your purchase before you hand over any money.
What IGI Is
The International Gemological Institute (IGI) was established in Antwerp in 1975. It operates grading laboratories in Antwerp, New York, Mumbai, Hong Kong, Bangkok, Tokyo, Dubai, and several other cities.
IGI is one of the world's largest and most widely recognised gemological laboratories. It grades both mined and lab-grown diamonds using the same methodology and standards. An IGI-graded lab-grown diamond is graded with exactly the same rigour as an IGI-graded mined diamond.
The Mumbai laboratory is particularly relevant for Indian buyers, since many diamonds sold in India are graded there. The certificate is the same regardless of which IGI laboratory produced it.
Other well-known diamond grading organisations include GIA (Gemological Institute of America), which is often considered the global standard for mined diamonds, and the HRD Antwerp Certificates. In India, IGI is the most commonly encountered certification for lab-grown diamonds and is broadly accepted across the retail and insurance markets.
The 4Cs: What They Mean for Lab-Grown Diamonds Specifically
The 4Cs (colour, clarity, cut, carat) are the universal language of diamond quality. IGI applies the same grading scales to lab-grown and mined diamonds. Here is what each grade means and how to think about it for your purchase.
Colour
The diamond colour scale runs from D (completely colourless) to Z (light yellow or brown tint visible to the naked eye). The scale was established by GIA and adopted universally.
| Grade range | Description | What it looks like |
|---|---|---|
| D, E, F | Colourless | Absolutely no visible colour. Rare. |
| G, H | Near-colourless | No visible colour to the naked eye in most settings |
| I, J | Near-colourless, slightly warm | Slight warmth detectable in large sizes or white settings |
| K, L, M | Faint yellow | Warmth visible, especially in face-up view |
| N to Z | Very light to light yellow | Visible colour, increasingly saturated |
For white metal settings (white gold, platinum), G to H is the practical sweet spot: no visible colour but without the Flawless-range premium. For yellow or rose gold settings, H to J is excellent value because the metal reflects warmth into the stone anyway.
One important note for lab-grown diamonds: because CVD growth can sometimes produce stones with a slight brownish or greyish tint, IGI will note these tints on the report. If a stone has been treated to improve its colour post-growth, this must be disclosed on the IGI certificate.
Clarity
Clarity refers to the presence of internal characteristics (inclusions) and surface characteristics (blemishes) in a diamond. IGI grades clarity under 10x magnification.
| Grade | What it means |
|---|---|
| FL (Flawless) | No inclusions or blemishes under 10x magnification |
| IF (Internally Flawless) | No inclusions; minor surface blemishes only |
| VVS1, VVS2 | Inclusions extremely difficult to see under 10x magnification |
| VS1, VS2 | Inclusions minor, not visible to the naked eye |
| SI1, SI2 | Inclusions noticeable under 10x; may or may not be eye-clean |
| I1, I2, I3 | Inclusions visible to the naked eye; affect brilliance |
For most buyers, VS2 is the value target: IGI confirms the stone is eye-clean, but you are not paying the VVS premium for perfection that requires a loupe to detect.
Lab-grown diamonds often have fewer inclusions than mined diamonds of the same size because the growth environment is controlled. FL and VVS grades are more common in lab-grown production than in mined diamonds. This is a genuine advantage, not a marketing claim.
Cut
Cut is the most important of the 4Cs for brilliance. A well-cut diamond returns light through the table to the eye. A poorly cut diamond leaks light through the base and looks flat regardless of its colour or clarity.
IGI grades cut for round brilliant diamonds as: Excellent, Very Good, Good, Fair, Poor.
For round brilliants, only Excellent or Very Good cut should be considered. The difference in light performance between Excellent and Good is visible to the naked eye.
For fancy shapes (oval, pear, cushion, emerald, princess), IGI does not assign an overall cut grade but does grade polish and symmetry. For these shapes, look for Excellent or Very Good in both polish and symmetry.
Carat
Carat is weight, not size. One carat equals 0.20 grams. IGI measures carat weight precisely on calibrated scales.
The certificate will state carat weight to two decimal places (e.g., 1.02 carats). This precision matters because prices jump at certain thresholds (0.50ct, 0.70ct, 0.90ct, 1.00ct). A stone at 0.98 carats may look identical to a 1.00 carat stone but cost meaningfully less.
What Else the IGI Certificate Covers
Beyond the 4Cs, an IGI certificate for a lab-grown diamond includes:
Growth method disclosure. The certificate states whether the diamond was grown by CVD (Chemical Vapour Deposition) or HPHT (High Pressure High Temperature). This is a mandatory disclosure for lab-grown stones. It does not indicate quality difference — both methods produce gem-quality diamonds. It is disclosed for transparency.
Treatment disclosure. If a lab-grown diamond has been colour-treated or clarity-treated, the certificate must state this. An untreated stone and a treated stone at the same colour grade are different products. Treatment does not make a stone inferior, but it should be priced accordingly and disclosed.
Polish and symmetry. Graded separately from cut. Excellent or Very Good in both indicates a well-finished stone.
Fluorescence. Some diamonds emit a blue glow under UV light. Strong fluorescence in a D to F colour stone can make it appear slightly hazy in sunlight. In G to J colour stones, moderate fluorescence can actually improve the stone's appearance by counteracting slight yellow warmth.
Proportions diagram. A visual representation of the stone's cross-section with measurements. Useful for verifying the physical dimensions of the stone match what you receive.
How to Verify an IGI Certificate in India
Every IGI certificate has a unique report number. You can verify any IGI report at igi.org by entering this number. The online verification returns the stone's full grading data, which should match the physical or digital certificate exactly.
Do this before finalising any purchase. It takes thirty seconds and eliminates any possibility of receiving a non-certified stone with a duplicated certificate number.
At Nivara, the report number for every stone is provided at the time of purchase. You are encouraged to verify it.
Why IGI Certification Matters More for Lab-Grown Than for Mined
The lab-grown market is newer. Consumer understanding varies. Without certification:
- A seller could misrepresent a simulant (cubic zirconia, moissanite) as a diamond
- A seller could misrepresent quality grades without documentation
- A seller could fail to disclose colour or clarity treatments
- A buyer has no recourse if the stone does not match what was claimed
With IGI certification: - The stone's properties are documented by an independent party - Treatment disclosure is mandatory - Growth method is stated - The certificate is verifiable online - The buyer has a document for insurance and future reference
This is why Nivara does not sell uncertified diamonds. The certificate is not an optional premium feature. It is the baseline standard for every purchase.
Browse IGI-certified lab-grown diamond jewellery at Nivara
Frequently Asked Questions
Is IGI the same standard as GIA for lab-grown diamonds? Both are respected international grading organisations. GIA is the originator of the 4Cs system and is considered the benchmark for mined diamonds. IGI is widely recognised for both mined and lab-grown diamonds and is the most commonly encountered certification in the Indian lab-grown market. The grading scales are identical.
Can I verify my IGI certificate online before buying? Yes. Every IGI certificate has a unique report number. Enter it at igi.org to verify the stone's full grading data independently of what the seller tells you. This verification is free and takes under a minute. Nivara provides the report number with every purchase.
Does the growth method on the certificate (CVD vs HPHT) affect the diamond's quality? No. Both CVD and HPHT produce gem-quality diamonds across the full range of grades. The growth method on the certificate is a disclosure of origin, not a quality indicator. Neither method is inherently superior.
What does it mean if my IGI certificate says a stone was "treated"? It means the stone underwent a post-growth process, typically to improve colour or clarity. Treated stones are real diamonds and can be excellent value, but they should be priced lower than untreated stones of the same grade and the treatment should always be disclosed.
How long is an IGI certificate valid? IGI certificates do not expire. The grading reflects the stone's properties at the time of testing. A diamond's physical properties do not change over time, so the certificate remains accurate indefinitely.
Do I need to do anything with my IGI certificate after purchasing? Keep the certificate in a safe place. You will need it for insurance purposes, for any future upgrade or trade-in claim, and as documentation if the ring ever needs repair or stone replacement. Photograph both sides of the certificate and store the image separately as a backup.
Want to see IGI-certified lab-grown diamonds in person? Book a showroom visit in Hyderabad, Bangalore, or Indore. We will walk you through the certificate for every stone you consider.
