What a GIA report is – and what it is not
The Gemological Institute of America (GIA) is a non-profit institute founded in 1931 that grades diamonds independently. A GIA Diamond Grading Report describes one individual stone: weight in carats, measurements in millimetres, colour, clarity, cut grade (round brilliants only), polish, symmetry, fluorescence and the position of inclusions in a plotting diagram. The report is not a valuation and not a sales contract; it is a description of physical properties on a given date.
Every report carries a unique number. With it the report can be retrieved online – that is the core of every check.
Step 1: Find the report number
The report number is printed at the top of the paper report, shown on the stone's page in our shop next to the laboratory code and – on most GIA stones – laser-inscribed on the girdle (the thin edge between the upper and lower part of the diamond). It usually has ten digits; older reports can be shorter.
In our shop the number is linked: one click opens the laboratory's verification service with the number filled in.
Step 2: Open GIA Report Check
The official service is called GIA Report Check and lives at gia.edu/report-check-landing. Enter the report number. For some reports GIA also asks for the carat weight to rule out random hits.
Use only GIA's own address. A verification page a dealer runs on its own domain proves nothing.
Step 3: Compare the entries
Report Check shows the data GIA holds for the stone. Compare point by point with what you have:
| Entry | What to look at |
|---|---|
| Carat Weight | Must match exactly to two decimal places. |
| Measurements | Length × width × depth in millimetres – a stone can be measured with callipers. |
| Shape and Cutting Style | For example "Round Brilliant" or "Cushion Modified Brilliant". |
| Color Grade | Letter D to Z; for coloured stones the fancy description. |
| Clarity Grade | FL, IF, VVS1, VVS2, VS1, VS2, SI1, SI2, I1, I2, I3. |
| Cut Grade | Round brilliants only: Excellent to Poor. |
| Polish / Symmetry | Excellent, Very Good, Good, Fair, Poor. |
| Fluorescence | None, Faint, Medium, Strong, Very Strong. |
| Inscription(s) | The number engraved on the girdle, if any. |
If an entry does not match, either the report is not the one for this stone or the paper has been altered. In both cases: do not buy until the dealer has explained the discrepancy.
Step 4: Read the laser inscription
GIA engraves the report number microscopically on the girdle of most stones. With a 10× loupe and some practice, or with a microscope at a jeweller, it can be read. The inscription ties the paper to the physical stone: a report can be copied, the inscription in the diamond cannot be without leaving traces.
If an inscription is missing although the report lists one, or the report lists none although the stone carries one, ask. There are harmless reasons (older reports, later inscriptions), but they need explaining.
Step 5: Match the plotting diagram
The full report contains a plotting diagram: a drawing of the stone from above and below with the inclusions marked. A gemmologist can compare the stone under the microscope with this drawing – the surest proof that stone and report belong together. For a distance purchase, have the stone checked by an independent gemmologist or jeweller after receipt; the statutory right of withdrawal for consumers in the EU gives you 14 days for that.
What differs at IGI and HRD
The two other laboratories whose reports appear in our shop offer the same service:
- IGI (International Gemological Institute): igi.org/verify-your-report – enter the report number, compare the data.
- HRD Antwerp: my.hrdantwerp.com – enter the report number, compare the data.
The scales are the same at all three laboratories (4Cs after the GIA system); the terms can differ slightly – HRD writes "Loupe Clean" instead of "Internally Flawless", for instance.
Common mistakes
- Looking only at the paper, not at the online data: paper can be forged, the laboratory's database cannot.
- Typing the number from a dealer's page instead of using the link to the laboratory.
- Comparing weight "roughly": 1.50 ct and 1.52 ct are two different stones.
- Taking the report for a valuation: it describes the stone, nothing more.
Which GIA documents exist
GIA issues several document types, and it pays to know which one you have. The Diamond Grading Report is the full document with plotting diagram and all proportions. The Diamond Dossier is a compact version for stones under about two carats: no diagram, but always with a laser inscription, because there it is the only link between paper and stone. For coloured stones there is the Colored Diamond Grading Report, for origin statements the Diamond Origin Report, for which GIA examined the rough before cutting. All types carry a report number and can be retrieved via Report Check; for some years GIA has issued many reports only digitally as eReports, which makes the online check all the more important.
How we do it at STIG International
Every stone in our listing is shown with its report number, linked directly to the laboratory's verification service. We show every value exactly as it appears on the report, and the original certificate is enclosed with every delivery. Check before you talk to us – that is what the number is for.