When a diamond arrives with an IGI certificate, most buyers look for the carat weight, briefly notice the certificate number printed on it, and move on. The rest of the document — ten to twenty additional data fields covering cut proportions, colour origin, clarity mapping, and fluorescence — goes unread. This is not a criticism. No one teaches buyers how to read a grading report, and the document itself is dense. But the fields that get ignored are often the most useful ones for understanding exactly what you have purchased.

This article goes field by field. Not as a lecture, but as a practical reference you can keep open while you look at a certificate. Every VAIMA diamond ships with an IGI certificate number that can be verified independently on the IGI website. The process takes under two minutes. This guide explains that process and every piece of data behind it.

20+data fields per certificateA standard IGI grading report covers identity, 4Cs, proportions, finish, and optical characteristics. Most buyers read fewer than five.
IGIfounded 1975, AntwerpInternational Gemological Institute. One of three globally recognised grading laboratories alongside GIA and HRD. Issues certificates for both lab-grown and mined diamonds.
2 minto verify onlineAny IGI certificate can be independently verified at igi.org. Certificate number from the physical report is all that is required. Verification is free.

What an IGI Certificate Actually Is

An IGI diamond grading report is a document issued after a trained gemologist examines a loose diamond under standardised laboratory conditions. The stone is assessed across multiple dimensions — weight, dimensions, cut quality, colour, clarity — and every finding is recorded with a corresponding grade. The certificate number is a permanent identifier for that specific stone.

Critically, a certificate does not guarantee value. It does not guarantee the diamond will hold its price, appreciate, or perform in a certain way. It describes what the stone physically is. A well-graded stone with a strong certificate can still be set in poor-quality metalwork, sold with dishonest markup, or misrepresented in the context it is sold in. The certificate answers the question of what the diamond is. Verification of the other elements — metal quality, making charge, seller transparency — requires separate due diligence.

Lab-Grown Disclosure: IGI certificates for lab-grown diamonds carry an explicit "Laboratory Grown" notation on the report. This notation also appears lasered into the girdle of the stone as a microscopic inscription. Both are visible on the certificate and verifiable independently. VAIMA only sells IGI-certified lab-grown diamonds.
IGI Certificate — Field ReferenceFields marked with · are the four most critical for purchase decisions

Identity & Identity Verification

Report Numbere.g. LG612345678Unique identifier for this specific stone. Prefix "LG" confirms lab-grown origin. Use this number to verify the certificate on igi.org. Never purchase a certified diamond without confirming this number matches what is on screen.
Report Datee.g. 12 March 2024Date the stone was graded. Not a sell-by date. For lab-grown diamonds, grading standards have remained consistent — a certificate from 2020 carries the same weight as one from 2024.
Shape & Cutting Stylee.g. Round Brilliant, Princess, OvalThe geometric shape of the stone (round, oval, cushion, princess, pear, emerald, marquise) and the cutting technique applied. Most VAIMA stones use Round Brilliant or Oval, both optimised for light return.
Measurementse.g. 4.20 – 4.22 × 2.60 mmPhysical diameter and depth in millimetres. For rounds: min diameter – max diameter × depth. Useful for verifying the stone physically matches what you were sold, and for sizing settings correctly.
OriginLaboratory GrownOn IGI certificates for lab-grown stones, this field explicitly states "Laboratory Grown." This line should never be absent. If purchasing a stone described as lab-grown and this field reads otherwise, do not proceed.

The 4Cs — Core Grading Fields

Carat Weighte.g. 0.50 ctPhysical mass of the stone. One carat equals 0.2 grams. Weight is measured to two decimal places. Note that carat weight and visual size are not the same — a well-cut 0.50ct stone can appear larger than a poorly cut 0.55ct stone.
Colour Gradee.g. F, G, HGIA scale: D (colourless) through Z (visible yellow/brown). D–F colourless, G–J near-colourless. For most settings and skin tones, G or H represents the optimal balance of quality and price. See article B5 for the full comparison.
Clarity Gradee.g. VS1, VS2, VVS2Assessment of internal inclusions (crystals, clouds, feathers, needles) and surface blemishes under 10× magnification. FL (flawless) through I3 (obvious inclusions visible to naked eye). VS1–VS2 recommended for daily wear.
Cut Gradee.g. Excellent, Very GoodApplies to Round Brilliant cuts only. Assesses how effectively the stone reflects light. Grades: Excellent, Very Good, Good, Fair, Poor. Excellent cut has the most impact on how a stone appears to the eye. Never compromise below Very Good.

Finish & Optical Properties

Polishe.g. ExcellentQuality of the surface finish on each facet. Affects how cleanly light enters and exits. Excellent or Very Good on any reputable stone. Poor polish creates a slightly milky or dull surface visible under magnification.
Symmetrye.g. ExcellentHow precisely the facets align and correspond. Poor symmetry means light exits unevenly, creating a slightly off-centre or unbalanced visual. Aim for Excellent or Very Good here alongside cut grade.
Fluorescencee.g. None, Faint, Medium BlueWhether the stone emits visible light under UV. None or Faint has no meaningful impact on appearance in normal light. Strong blue fluorescence in high-colour stones (D–F) can occasionally create a slightly hazy appearance. For G–I colour, Medium Blue fluorescence is considered neutral to beneficial by many gemologists.

Proportions & Clarity Plotting

Depth %e.g. 62.1%Depth as a percentage of average diameter. Ideal range for Round Brilliant: 59%–62.5%. Too shallow = light leaks through the bottom; too deep = stone looks small for its weight. This field directly impacts how much fire and brilliance the stone displays.
Table %e.g. 57%Size of the flat top facet as a percentage of diameter. Ideal: 54%–58% for Round Brilliant. A table that is too large directs light straight through rather than reflecting it. Often overlooked but relevant to overall optical performance.
Girdlee.g. Thin to Slightly Thick, FacetedEdge of the stone between crown and pavilion. Also where the IGI laser inscription appears. Extremely thin girdles risk chipping during setting. Extremely thick girdles add hidden weight. Medium to Slightly Thick faceted is ideal.
Clarity Characteristics PlotMapped diagram on certificateDiagram showing the position and type of inclusions within the stone. Red symbols = internal inclusions (crystals, clouds, feathers). Green symbols = surface blemishes. The plot lets you verify the stone you have physically matches the mapped stone in the report.

How to Verify Your Certificate Online

IGI provides a public verification portal. Any certificate number can be checked there for free. This takes roughly two minutes and confirms that the certificate exists, has not been tampered with, and matches the stone specification you were sold. It is the one step between receiving a piece of jewellery and being certain of what you have.

Certificate Verification — Step by Step

1
Locate the report number on your certificate or product page
Every VAIMA product page displays the IGI certificate number alongside the diamond specification. On the physical certificate, the report number appears in the top-right section. For lab-grown stones, it begins with LG followed by nine digits.
2
Go to igi.org and click Report Check
On the IGI homepage, the report verification tool is under Report Check in the top navigation. This takes you directly to the verification field. Do not use third-party sites that claim to verify IGI certificates.
3
Enter the report number exactly as it appears
Type the full number including the LG prefix. The system is case-sensitive. If you receive a "no results" error, check for a typo. Valid IGI certificates will always return a result.
4
Cross-check every field against your physical certificate
The online record shows carat weight, colour, clarity, cut, shape, measurements, and the origin notation. Every field on the screen should match exactly what is printed on your certificate. Pay particular attention to the origin field — it must read "Laboratory Grown" for a lab-grown stone.
5
Check the girdle inscription if physically accessible
With a loupe (10×) or jeweller's magnification, the IGI report number and "Laboratory Grown" notation appear inscribed on the girdle of the stone. This connects the physical stone to its certificate. For VAIMA pieces post-setting, this requires careful examination at the stone's edge. Not essential for every buyer, but available to confirm for those who want it.

Which Grades to Buy: A Practical Reference

The 4Cs exist on paper. What matters for a daily-wear piece — something worn on your commute, in meetings, through Mumbai's monsoon, through Delhi's dry heat — is slightly different from what looks best on a grading certificate. Here is a practical buying guide based on grades, not theory.

4Cs Grade Guide — What to Look For in Daily-Wear Fine Jewellery

Grade TypeRecommended RangeWhyWhat to Avoid
Cut
Round Brilliant only		ExcellentCut has the most visible impact on how a stone looks. An Excellent-cut stone in G colour outperforms a D-colour stone with Good cut. This is the one grade to never compromise on.Good or below. Fair/Poor cuts create light leakage, making a stone look dim or glassy regardless of colour or clarity.
Colour
D–Z scale		G–H F for platinumG and H appear colourless to the naked eye in most settings. In yellow gold, H–I actually complements the metal. The premium for D–F is real but the visual difference is not perceptible without side-by-side comparison under lab lighting.J or below for white metals. Visible warmth becomes noticeable in platinum or white gold settings. In yellow gold, J can work depending on preference.
Clarity
FL through I3		VS1–VS2 VVS2 for larger stonesVS inclusions are not visible to the naked eye. VVS inclusions are microscopic. Both grades are eye-clean in normal wear and viewing. SI1 can be eye-clean if inclusions are positioned away from centre; requires stone-by-stone review.I1 and below for jewellery. Inclusions become visible and can affect durability in prong-set or tension-set designs. FL and IF grades carry a significant premium for no visible benefit in daily wear.
Carat
Weight, not size		0.30–0.70ct for ringsFor daily-wear solitaire rings, 0.40–0.60ct hits the sweet spot of visible presence without impractical height. Earrings work well at 0.10–0.20ct per stone. Consider setting style: bezel settings make stones appear larger; solitaire prong settings show weight most honestly.Chasing round carat numbers (0.50ct exactly vs 0.48ct) at the cost of cut or clarity. A 0.48ct Excellent cut outperforms a 0.52ct Good cut visually and as an investment in long-term satisfaction.
Polish & Symmetry
Finish grades		Excellent / Very GoodBoth fields should be Excellent or Very Good for any fine jewellery piece. Below Very Good introduces microscopic surface imperfections that, while not visible in isolation, collectively reduce the vibrancy of light return over time.Good and below. Avoid compromising here to lower price — these grades affect the stone's visual performance more than buyers realise.
Fluorescence
UV reaction		None to Faint Medium Blue acceptable in G–INone or Faint fluorescence carries no impact in daylight. Medium Blue in G–I colour stones is considered neutral to positive by many gemologists and is priced slightly lower. Strong fluorescence in D–F stones can create a hazy appearance.Strong or Very Strong fluorescence in high-colour (D–F) stones. The hazy effect, though rare, appears in a subset of these stones and cannot be verified without physical inspection.

Independent Verification

Your certificate number on its own verifies nothing.
Checking it on igi.org verifies everything.

1
Find the LG-prefixed report number on your certificate or VAIMA product page.
2
Visit igi.org → Report Check. No account needed.
3
The database returns all graded fields. Confirm origin reads "Laboratory Grown" and every grade matches your receipt.
4
Done. Two minutes. No jewellery knowledge required beyond what this article gave you.
→ igi.org/report-check

What the Certificate Does Not Tell You

A grading report covers the stone. It says nothing about the metal it is set in, the making charge applied, whether the BIS hallmark on the gold is genuine, whether the setting will hold the stone securely, or whether the price you paid was honest.

This is why VAIMA treats specification transparency as a complete package. Every product page shows: the IGI certificate number with a direct link to igi.org, the BIS HUID number for gold and platinum pieces with a link to the government verification portal, the metal weight in grams, the live IBJA rate applied on the day of order, and the making charge percentage. The certificate is one layer. The rest of the specification is built around it.

"A certificate tells you what the diamond is. The rest of the bill of sale tells you whether you were treated fairly."

If a seller provides an IGI certificate but withholds the metal weight, the making charge, or the diamond's role in the total price — that is not transparency. That is a single piece of documentation used to create the appearance of transparency. Know the difference before you buy.