Diamond Education · diamond-certification

Diamond Certificates & Grading Reports: IGI, GIA & What They Mean

A diamond certificate — also called a grading report — is an independent laboratory's written assessment of one diamond's cut, colour, clarity and carat weight, issued by a gemmological lab with no financial stake in the sale. It records what a diamond is; it does not state what it is worth.

Arta Talachian Published 20 July 2026 · Reviewed 6 September 2026 · 6 min read
IGI diamond report brochures displayed beside a loose round brilliant diamond

Quick Answer

A diamond certificate is an independent grading report documenting a diamond's cut, colour, clarity and carat weight, issued by a gemmological laboratory with no financial interest in the sale. It is a scientific record, not a valuation. Whether a DEEVE piece includes an individual IGI certificate is recorded per piece. The many small stones set in tennis bracelets and eternity bands are IGI-graded but not individually certified, whatever the total carat weight, because there is no single stone for a certificate to describe.

A diamond certificate — also called a grading report — is an independent, third-party assessment of a diamond's quality. It is issued by a gemological laboratory and documents the diamond's characteristics using standardized grading criteria. At DEEVE, every lab-grown diamond in our engagement rings and diamond stud earrings comes with an IGI certificate. Here is everything you need to know about what those certificates mean and how to use them.

Part of our complete lab-grown diamond guide.

What Is a Diamond Certificate?

A diamond certificate is not an appraisal or a valuation — it is a scientific grading report. It tells you exactly what you are buying: the diamond's cut, colour, clarity, and carat weight (the 4Cs), along with additional measurements, proportions, and finish grades. Certificates are issued by independent laboratories with no financial interest in the sale, making them the most reliable way to verify a diamond's quality.

IGI Certification: DEEVE's Standard

DEEVE uses the International Gemological Institute (IGI) for all lab-grown diamond certification. IGI is the world's largest independent gemological laboratory and applies the same grading standards to lab-grown diamonds as to natural diamonds.

What an IGI certificate includes:

  • Report number — unique identifier, verifiable online at igi.org
  • Shape and cutting style — e.g., Round Brilliant, Oval, Princess
  • Measurements — diameter and depth in millimetres
  • Carat weight — precise to the hundredth of a carat
  • Colour grade — D (colourless) through Z (light yellow)
  • Clarity grade — FL (flawless) through I3 (included)
  • Cut grade — Excellent, Very Good, Good, Fair, Poor
  • Polish and symmetry — assessed separately
  • Fluorescence — None, Faint, Medium, Strong, Very Strong
  • Laser inscription — the report number is laser-inscribed on the diamond's girdle, allowing physical verification
  • Clarity diagram — a map of inclusions and blemishes

See our field-by-field IGI certificate guide →

DEEVE's 4Cs Standards

  • Cut: Excellent on all IGI-certified lab-grown diamonds (engagement rings, diamond studs)
  • Colour & Clarity: Stated on each individual IGI certificate; tennis bracelet diamonds are IGI-graded at F–G colour, VS2–SI1 clarity but ship without an individual certificate, because the bracelet is built from many small stones rather than one large one
  • Carat: Precise weight verified and stated on the certificate
  • Natural diamonds: conflict-free and responsibly sourced

IGI vs. GIA: What's the Difference?

Feature IGI GIA
Lab-grown diamond grading ✓ Full grading ✓ Full grading
Natural diamond grading ✓ Full grading ✓ Full grading
Laser inscription ✓ Included ✓ Included
Online verification igi.org gia.edu
Industry recognition Widely accepted globally Widely accepted globally

A third laboratory you may encounter is GCAL — the Gem Certification & Assurance Lab, based in the United States. GCAL is distinctive in issuing guaranteed certifications — it stands behind its grading results — and is best known for its 8X cut grade, which assesses cut precision across eight optical and craftsmanship criteria. DEEVE’s lab-grown diamonds are certified by IGI, but if you are comparing certificates across retailers, a GCAL report is read the same way: the 4Cs remain the common language.

What a Certificate Does Not Tell You

A grading report is a description, not a verdict. It records measurable facts about one stone and stops there, and three things it is routinely expected to do are outside its scope.

  • It is not a valuation. A certificate carries no price and implies none. An appraisal is a separate document written for insurance, and it answers a different question — what replacing the piece would cost, not what the stone is.
  • It does not rank beauty. Two diamonds with identical paperwork can look markedly different once set. Grades are measured on a loose stone under controlled light; you will wear it in a setting, in daylight, on a hand.
  • It does not describe the piece. The report covers the diamond. The metal, the setting, the workmanship and the clasp are not on it, and those are what decide whether a piece survives daily wear.

Read the Report in the Order That Decides the Stone

The fields above are printed in a conventional order, which is not the order in which they matter.

  • Cut, polish and symmetry come first. They govern how the diamond behaves in light. A well-cut stone at a lower colour grade routinely outperforms a poorly cut stone with better paperwork, and cut is the one grade the eye reads immediately.
  • Then clarity, judged as eye-clean or not. The grade letter matters less than whether inclusions are visible without magnification. VS2 and SI1 are frequently eye-clean at a fraction of the cost of the grades above them.
  • Then colour, judged against the metal. Near-colourless grades read as colourless once set in yellow or rose gold. Paying for the top of the scale makes sense in white metal and rarely elsewhere.
  • Carat last. It is a weight, not a size. Two stones of equal weight can present very differently depending on how the cutter distributed it.

How to Verify Your Diamond Certificate

  1. Locate the report number on your IGI certificate
  2. Visit igi.org and enter the report number in the verification tool
  3. The full grading report will appear, confirming all details match your physical certificate
  4. You can also verify the laser inscription on the diamond's girdle under 10× magnification

What a Failed Verification Actually Means

A mismatch between the certificate and the online record is not automatically fraud. Report numbers get transcribed wrongly, and a stone that has been re-cut is re-graded, which retires the old report.

But a discrepancy is always a question to put to the seller before money moves, and a seller who cannot resolve it has told you something useful. The inscription matters most of all here: it is the only thing tying the paper to the physical stone. Everything else on the report describes a diamond — not necessarily this diamond.

And If There Is No Certificate At All

Plenty of diamonds are sold without any independent report. That is common in the wider market and it is not by itself a sign of a bad stone — but it changes what you are relying on.

Without a report, every grade you are quoted is the seller's own assessment of something the seller is trying to sell you. That is a different kind of statement from a laboratory's, and it cannot be checked. If a stone is offered with grades but no issuing laboratory named, treat the grades as an opinion rather than a finding, and price the uncertainty into what you are willing to pay.

A Note on Tennis Bracelet Diamonds

Lab-grown diamond tennis bracelets at DEEVE use diamonds that are IGI-graded at F–G colour and VS2–SI1 clarity, cut to Excellent. They ship without an individual certificate because of what the piece is, not because of any lab policy: a tennis bracelet is built from many small stones rather than one large one, so there is no single stone for a certificate to describe. DEEVE's rule follows the piece — certification is recorded per piece and stated on its listing, while tennis bracelets and eternity bands are IGI graded to the same standard without an individual certificate, whatever their total carat weight. The grading information is verified at the batch level and reflected in the product specifications.

Every DEEVE diamond purchase is backed by our lifetime warranty and full transparency on materials and certification. Questions? Visit our Materials & Authenticity page or contact us directly.

What to remember

  • A certificate grades a diamond; it does not value one. An appraisal is a separate document, written for insurance rather than for comparison.
  • The report number can be checked against igi.org in under a minute, and should match the laser inscription on the diamond's girdle.
  • A tennis bracelet or eternity band is built from many small stones rather than one large one — which is why those diamonds are IGI-graded rather than individually certified, whatever the total carat weight.
  • Read the cut, polish and symmetry lines before the colour and clarity grades. An Excellent cut on a G colour stone outperforms a poorly cut D.

How to Read a Diamond Certificate

Six checks, in order

  1. Confirm the issuing laboratory and locate the report number at the top of the document
  2. Read the cut, polish and symmetry grades first — they govern how the diamond behaves in light
  3. Check colour and clarity against the setting metal; near-colourless grades read as colourless in yellow gold
  4. Verify the report number online at the laboratory's own site, never on a page supplied by the seller
  5. Match the laser inscription on the girdle to the report number under 10× magnification
  6. Confirm whether the report states a growth method — CVD or HPHT — if the diamond is lab-grown

From the bench

A certificate proves grading, not beauty. Two stones with identical paperwork can look markedly different once set

Keep the report with the insurance valuation rather than with the piece — the two documents answer different questions

If a seller offers no report and no laboratory name, treat the grades quoted as an opinion rather than a finding

Mentioned above 2ct Round Lab Grown Diamond Ring | 14K Gold $2,664.00 View the piece

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The first thing I do with a certificate is skip the headline grades and read the cut, polish and symmetry line. I have set VS1 stones that sat dull because the proportions were off, and SI1 stones that carried a room. The grades tell you what you bought. The cut tells you what you will actually see on the hand.
— Arta Talachian, 5th-Generation Master Goldsmith & Certified Gemologist

FAQ

Questions, answered.

What is the difference between a diamond certificate and a diamond appraisal?
A certificate describes; an appraisal values. A grading report from IGI or GIA records measurable characteristics — cut, colour, clarity, carat weight, proportions, finish — and states no price. An appraisal assigns a monetary figure, usually for insurance, and is written by a valuer rather than a grading laboratory. The certificate is what lets you compare two diamonds; the appraisal is what lets you insure one.
Why is a tennis bracelet diamond IGI-graded but not IGI-certified?
A tennis bracelet is a strand of many small stones rather than one principal diamond. The diamonds are still graded to a stated standard — F–G colour, VS2–SI1 clarity — and that grading is verified and recorded, but no separate certificate accompanies each stone. Certificate and grade are not the same claim, and DEEVE states which applies on every listing.
Does a diamond grading report ever expire?
No. A grading report has no expiry date, because the characteristics it records do not change. What can change is the diamond itself — a chipped girdle or a re-cut stone no longer matches its report. Grading standards are also revised occasionally, so a report from a much earlier era may use terminology a current one would not. For insurance purposes, the valuation attached to a diamond is what needs refreshing, not the grading report.
What is the laser inscription on a diamond, and how do I read it?
It is the report number etched onto the girdle — the narrow band around the diamond's widest point — in characters far too small to see unaided. Under 10× magnification it reads as a line of text that should match the number on the certificate exactly. It is the link between the paper and the stone, and checking it is the one step that confirms the report in your hand belongs to the diamond in your setting.

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