A GIA report is the most useful document in a diamond purchase, yet most buyers read only its top lines. This guide takes the current GIA Diamond Grading Report field by field and explains what each line means for the stone you are buying. Every diamond we sell carries a GIA or HRD report, so you can practise on real ones among our GIA-certified diamonds and HRD-certified diamonds.
What a GIA report is
GIA, the Gemological Institute of America, is the independent, non-profit laboratory that created the 4Cs and the D-to-Z colour scale. Its Diamond Grading Report, headed “Natural Diamond Grading Report” on recent issues, covers loose natural diamonds of 0.15 carat and above; laboratory-grown diamonds receive a different document. For smaller stones GIA also issues a shorter Diamond Dossier, with the same grades but no plotted map of inclusions.
The report at a glance
| Field | What it records | What to look for |
|---|---|---|
| Date | When GIA examined the stone | An older date is normal |
| Report number | The stone’s entry in GIA’s database | Check it on GIA’s website |
| Shape and cutting style | Outline and facet pattern | Matches the listing |
| Measurements | Dimensions in millimetres | Face-up size |
| Carat weight | Weight to the hundredth | Read with the measurements |
| Colour grade | D to Z | G or H faces up white |
| Clarity grade | FL to I3 | Read with the plot |
| Cut grade | Excellent to Poor, rounds only | Excellent, or a proven Very Good |
| Polish and symmetry | Finish and precision | Excellent or Very Good |
| Fluorescence | Glow under ultraviolet light | Strong or above: judge on video |
| Inscription(s) | Any text on the girdle | Recorded for identification |
| Comments | Anything not shown elsewhere | Read every word |
| Proportions diagram | Table, depth, angles, girdle, culet | Sensible depth and table |
| Plot and key to symbols | Map of inclusions and blemishes | Where they sit |
Identity: number, date, shape and measurements
Report number and date
The report number is the stone’s entry in GIA’s database and the number you enter in GIA’s Report Check. The date is when GIA examined the diamond, not when it was sold; an older report still describes the stone if it has not been chipped, recut or treated since.
Shape and cutting style
Shape is the outline seen from above; cutting style is the facet pattern. A standard round reads “Round Brilliant” and an oval “Oval Modified Brilliant”, while a princess cut usually appears as “Square Modified Brilliant”. Whatever the wording, it should match the listing.
Measurements
For a round, this line reads minimum diameter, maximum diameter and depth, for example 6.41 - 6.43 x 3.97 mm; for a fancy shape, length x width x depth. It tells you the face-up size you will actually see. Compare a round’s diameter with the typical figure in our carat and size guide: a stone that measures small for its weight is carrying hidden depth.
Grading results: carat, colour, clarity and cut
Carat weight
Weight is recorded to the hundredth of a carat; one carat is a fifth of a gram. Prices step up at round numbers such as one carat while visible size grows smoothly, so a stone just under a threshold can look the same as one just over it.
Colour grade
Printed as “Color Grade” in GIA’s American spelling, this measures the absence of colour on the D-to-Z scale, judged against GIA’s master comparison diamonds. D to F are colourless, G to J near colourless. An asterisk beside the grade means a colour treatment was detected. Our colour and clarity chart shows how each grade looks once set.
Clarity grade
Clarity is the relative absence of inclusions and blemishes, graded under 10× magnification on the size, nature, number, position and relief of each feature. The scale runs FL, IF, VVS1, VVS2, VS1, VS2, SI1, SI2, then I1 to I3. The letter is a summary; the plot is the detail.
Cut grade
GIA gives an overall cut grade, from Excellent to Poor, only to standard round brilliants in the D-to-Z colour range. It weighs face-up appearance, design and craftsmanship. Fancy shapes carry no cut grade, so their light has to be judged on the stone itself. Our guide to Excellent versus Very Good cut explains where the grades differ.
Additional grading information
Polish and symmetry
Polish grades the smoothness of the facets; symmetry grades the exactness of the outline and the alignment of the facets. Both run from Excellent to Poor, for every shape. A round graded Excellent for cut, polish and symmetry is what the trade calls Triple Excellent.
Fluorescence
This line gives the strength of the glow under long-wave ultraviolet light: None, Faint, Medium, Strong or Very Strong, with its colour, usually blue, named at the stronger grades. It is not a flaw and is invisible in most light, but a minority of strongly fluorescent stones look slightly hazy. Our fluorescence guide explains when it matters.
Inscription(s)
The report records any text, symbol or logo inscribed on the diamond’s girdle, most often “GIA” followed by the report number. The inscription is microscopic, part of how the trade identifies a stone, and not something a buyer should be expected to read or match. Your protection is simpler: buy from a reputable dealer who stands behind every stone matching its report, and check the report number online yourself. Our guide to choosing a diamond seller you can trust explains why.
Comments
Comments cover anything relevant the other lines do not show. “Clouds are not shown” or “Additional pinpoints are not shown” means some minor features were left off the plot, although the clarity grade still counts them. A detected treatment, such as laser drilling, is described here too.
The proportions diagram
The profile drawing shows the stone’s actual proportions. For a round brilliant it gives:
- Table: the width of the top facet, as a percentage of the diameter.
- Total depth: the height from table to culet, as a percentage of the diameter.
- Crown angle and height: the upper part, which shapes brightness and fire.
- Pavilion angle and depth: the lower part, which decides whether light returns or leaks out.
- Star and lower half lengths: two sets of facets that shape the sparkle pattern.
- Girdle: the thickness of the edge, from Extremely Thin to Extremely Thick, often as a range, with its finish and a percentage.
- Culet: the tip of the pavilion; “None” means it ends in a point.
Fancy shapes show a simpler profile. Many of the best-performing rounds have a table of about 53 to 58 per cent and a total depth of about 59 to 62.5 per cent, but the angles matter more, and the cut grade already weighs them together. A very thin girdle is prone to chipping; a very thick one adds hidden weight.
The clarity plot and key to symbols
The plotted diagram maps the stone from above and below, with symbols marking the type, position and approximate size of each clarity characteristic. Red symbols mark internal features (inclusions) such as crystals, feathers, clouds and needles; green or black symbols mark external ones (blemishes) such as a natural or an extra facet. The key to symbols lists each type shown; not every characteristic is necessarily plotted.
Read the map for position rather than count: a small feather near the girdle may never be seen once the stone is set, while the same feather under the table is another matter. That is the heart of choosing an eye-clean diamond, and you can look for plotted features as the stone turns on video.
Security features
A printed GIA report carries microprinting, security screens, watermarks, a hologram, sheet numbering and a QR code linked to GIA’s database. These make forgery difficult, but treat them as a first check, not proof. The PDF you can download from GIA’s website is marked as a facsimile, without the physical features. The decisive check is the report number in GIA’s own database, reached by your own route.
How HRD reports differ
HRD reports use the same 4Cs, with a few differences in wording. HRD’s top clarity grade is LC, loupe clean, where GIA uses FL and IF, and its lowest grades are P1 to P3 instead of I1 to I3. Fluorescence is described as nil, slight, medium or strong. Cut is set out as separate lines for proportions, polish and symmetry. An HRD report is checked the same way, on HRD’s own website; the practical comparison is in our guide to GIA vs HRD certificates.
How to verify a GIA report online
- Type GIA’s web address yourself, rather than following a link or QR code that arrives with the stone, and open Report Check.
- Enter the report number exactly as printed.
- Confirm that every line matches the paper and the listing, and that the report describes a natural diamond.
If anything differs, stop. The full method for both laboratories is in our guide on how to verify a GIA or HRD certificate online.
What a report does not tell you
A report confirms grades; it does not judge beauty. Two stones with identical reports can look different, because a report:
- does not say whether the stone is eye-clean: the plot shows where inclusions sit, not whether you will notice them;
- does not rank cut quality within a grade, so a dark bow-tie in an oval appears nowhere on the paper;
- does not show haze or transparency, which only the stone reveals, in daylight or on video;
- is not a valuation or a guarantee, as GIA states on every report.
That is why we film every diamond in a slow 360° turn and send the video with its report on WhatsApp. Our article on why the 360° video matters explains how to watch one, and our engagement ring buying guide puts the report in the context of the whole ring.
Common questions
Is a GIA certificate the same as a GIA report?
Yes. Buyers and the trade usually say “certificate”, while GIA calls the document a report, because it records findings rather than certifying a value. The Diamond Grading Report and the shorter Diamond Dossier are both checked the same way, by their number.
Why does my oval diamond’s GIA report have no cut grade?
GIA gives an overall cut grade only to standard round brilliants in the D-to-Z colour range. Ovals and other fancy shapes receive polish and symmetry grades only, so their brightness, outline and any bow-tie have to be judged on the stone itself, ideally on video.
What does “clouds are not shown” mean on a GIA report?
It means GIA left some small clouds, clusters of tiny pinpoints, off the plot to keep it readable, while the clarity grade still counts them. Most are invisible, but a large or dense cloud can soften brightness, one more reason to watch the stone on video.
Does a GIA report expire?
No. A GIA report has no expiry date, but it describes the diamond as it was on the date of examination. If the stone is later chipped, recut or treated, the report no longer describes it accurately, and a new report would be needed.
Does a GIA report show what the diamond is worth?
No. Every GIA report states that it is not a guarantee or a valuation. It records identity and grades, which drive price, but the price comes from the market. At diamonds.com.lb each stone’s price is shown on its own page, next to its report number.
How can I tell a GIA report is genuine?
Check the report number on GIA’s own website, reached by typing the address yourself, and confirm every line matches the paper and the listing. Printed reports also carry security features such as a hologram. Above all, buy from a reputable dealer.