You've been told your diamond comes with an IGI certificate. Great — but do you know what to look for on it? Most buyers glance at the carat weight and stop there. This guide walks you through every important section so you can verify exactly what you're getting.
What Is an IGI Certificate?
An IGI (International Gemological Institute) Diamond Grading Report is an independent document issued by a globally recognised gemological lab. It records the objective characteristics of a specific diamond — the 4Cs and more — after examination by trained gemologists using calibrated instruments.
IGI is one of the world's two major diamond grading labs (alongside GIA). In India, IGI is the most widely accepted standard. An IGI-certified diamond means the grades have been verified by a third party — not the seller.
The Report Number — Start Here
Every IGI report has a unique Report Number (also called Certificate Number) printed at the top. This is your verification key.
What to do: Go to igi.org/verify, enter the report number, and confirm the grades on the certificate match what's in the IGI database. If a seller can't provide this number, that's a red flag.
At My Carat, every product listing includes the IGI report number. You can verify before you even place an order.
Shape and Cutting Style
The report states the diamond's shape (Round, Princess, Oval, Cushion, Emerald, Pear, etc.) and its cutting style (Brilliant, Step, Modified Brilliant). A standard solitaire ring uses a Round Brilliant.
Measurements
For a round diamond, measurements are listed as minimum diameter × maximum diameter × depth in millimetres (e.g., 5.85–5.88 × 3.60 mm). This tells you the physical size of the stone — useful for comparing two diamonds of the same carat weight, since cut quality affects how "spread out" the weight is.
Carat Weight
Listed to two decimal places (e.g., 0.70 ct). This is the weight of the loose diamond before setting. Once set in a ring or pendant, the weight doesn't change — but you can't easily re-measure it. The certificate is your proof.
Colour Grade
IGI uses the standard D–Z scale. D, E, F are colourless (premium pricing). G, H, I, J are near-colourless (best value zone for most Indian buyers). Anything K or below has a visible yellow tint.
The colour grade is assessed on the loose stone, face-down, against a white background under controlled lighting — not inside a ring under shop lights. Always check the certificate, not your eye under showroom spotlights.
Clarity Grade
The clarity scale: FL → IF → VVS1 → VVS2 → VS1 → VS2 → SI1 → SI2 → I1 → I2 → I3.
The report also includes a clarity plot — a diagram of the diamond showing the exact position and type of each inclusion. Inclusions are marked with red symbols (internal) and green symbols (surface). This diagram is unique to your stone and another verification tool.
Cut Grade (Round Brilliant Only)
For round diamonds, IGI provides an overall Cut grade: Excellent, Very Good, Good, Fair, or Poor. This is arguably the most important number on the report. It summarises how well the diamond was proportioned and polished to return light to your eye.
Sub-grades are also listed: Polish and Symmetry. These contribute to the overall cut grade. Excellent/Excellent or Very Good/Excellent are what to look for.
Fluorescence
Fluorescence describes whether the diamond glows under UV light. It's graded: None, Faint, Medium, Strong, Very Strong. Most gem experts and buyers in India prefer None or Faint.
Strong blue fluorescence can occasionally make a D–F colour stone look milky in direct sunlight — rare but worth knowing. For G–I colour stones, faint to medium fluorescence has no noticeable effect and is sometimes used to get a slightly lower price.
Proportions Table
The proportions section gives you numbers like Table %, Depth %, Crown Angle, Pavilion Angle. These determine cut quality. For an Excellent-cut round brilliant, you're looking for: Table 54–58%, Depth 60–62.5%, Crown Angle 34–35°, Pavilion Angle 40.6–41°. If the cut grade says Excellent, these are already optimised.
The Laser Inscription
Most IGI-certified diamonds have the report number laser-inscribed on the girdle (the thin edge around the diamond's circumference). This is microscopic — visible only under 10× magnification — and it links the physical stone permanently to the certificate. A jeweller can verify it with a loupe.
What the Certificate Does NOT Tell You
- Whether the diamond is natural or lab-grown (IGI issues separate reports for lab-grown — look for "Lab-Grown Diamond Report" vs "Diamond Grading Report")
- Whether the diamond has been treated (fracture-filled or HPHT-treated stones require disclosure)
- The market price — that depends on current gold and diamond rates
My Carat's Commitment
Every diamond at My Carat ships with its IGI report. The report number is on the product page. If you want to verify before ordering, just ask us on WhatsApp — we'll send you the full report PDF.