Introduction
If you are shopping for diamonds across multiple retailers — particularly if some offer GIA-graded stones and others offer IGI-graded ones — you will need to read IGI reports with the same confidence you bring to a GIA document. The information is fundamentally the same: identification, measurements, 4Cs grades, finish, fluorescence, a clarity plot, and proportions data. What differs is how IGI labels certain fields, how it distinguishes natural from lab-grown diamonds on the document itself, and where its grading calibration sits relative to GIA's.
This article walks through an IGI Diamond Report section by section. It assumes you are already familiar with the general report-reading framework — if not, start with How to Read a Report. For background on IGI as an institution, its market position, and its grading calibration relative to GIA, see IGI Profile.
Key Points
Report header and identification
The top of an IGI report displays the IGI logo, report title, report number, and examination date. So far, identical to the GIA layout. The report number is unique to the stone and links it to IGI's online verification database — enter it on IGI's website to confirm the document is genuine. See Online Report Verification for the verification process.
Here is where the first critical distinction appears: the header identifies whether the diamond is natural or laboratory-grown. IGI natural diamond reports carry one colour scheme (typically blue), while lab-grown diamond reports use a different colour scheme (typically pink or orange) with the words "Laboratory Grown Diamond" printed prominently in the title. This colour coding is deliberate — it prevents a lab-grown report from being mistaken for a natural diamond report at a glance. Before reading any grades, confirm which type of report you are holding. See Natural vs Lab-Grown Overview for the broader context.
Shape, cutting style, and measurements
IGI records shape and cutting style using standard gemological terminology — "Round Brilliant," "Cushion Modified Brilliant," and so on — identical to GIA's conventions. Measurements appear in millimetres in the same format: minimum diameter – maximum diameter × depth for rounds, length × width × depth for fancy shapes.
No translation is needed between IGI and GIA on these fields. See Measurements on the Report for how to interpret the numbers.
The 4Cs grades
IGI grades colour, clarity, carat weight, and cut using the same foundational scales GIA created:
Colour: D-to-Z scale for diamonds in the normal colour range. The same letter grades, the same progression from colourless to light. See Normal Colour Range.
Clarity: Flawless through Included (I3), assessed at 10× magnification. Same scale, same criteria. See GIA Clarity Scale.
Carat weight: Recorded to the hundredth of a carat, measured on calibrated scales. No difference from GIA.
Cut grade: This is the most visible terminology difference between IGI and GIA. Where GIA's top cut grade is "Excellent," IGI uses "Ideal" as its highest designation for round brilliants. Below that, the scale continues with Excellent, Very Good, Good, and so on. In practical terms, an IGI "Ideal" roughly corresponds to what GIA calls "Excellent" — both indicate a round brilliant whose proportions, light performance, and craftsmanship meet the laboratory's highest standard. However, the proportion boundaries that define each grade differ between the two laboratories, so the correspondence is approximate, not exact. See Cut Grade Scale for GIA's methodology.
For the 4Cs panel in general, see 4Cs Panel on the Report.
Finish: polish and symmetry
IGI grades polish and symmetry on the same scale as GIA — Excellent through Poor. These appear in the same section of the report, alongside or immediately following the 4Cs panel. An IGI "Excellent" polish carries the same meaning as a GIA "Excellent" polish: the facet surfaces are smooth and well-finished under magnification. See Finish on the Report for what each grade indicates.
Fluorescence
IGI records fluorescence using terminology that aligns with GIA's: None, Faint, Medium, Strong, and Very Strong. When fluorescence is present, the colour is noted — most commonly blue. Unlike HRD, which uses "Nil" instead of "None," IGI matches GIA's vocabulary here. No translation is needed. See Fluorescence on the Report for interpretation.
Clarity plot
IGI's full Diamond Report includes a clarity plot that maps inclusions and blemishes onto a schematic view of the stone. The symbols follow standard gemological conventions, though IGI's visual style — line weights, rendering — may differ slightly from GIA's. The information is the same: what types of inclusions are present, where they sit relative to the table, and whether they are internal or external characteristics.
As with any clarity plot, the question to ask is practical: are the plotted inclusions located where they will be visible face-up, or are they positioned near the girdle where a setting could conceal them? See Clarity Plot on the Report for interpretation techniques.
Proportions data
IGI reports include the standard set of proportions measurements: table percentage, crown angle, pavilion angle, total depth percentage, girdle thickness, and culet size. These are the same data points GIA reports, derived from the same physical geometry of the diamond. The presentation format may differ — IGI may use a different visual layout for the proportions diagram — but the numbers carry the same meaning. See Proportions Diagram on the Report for how to evaluate them.
Hearts-and-arrows imagery
Some IGI reports — particularly the dedicated Hearts and Arrows Report — include photographs of the hearts-and-arrows pattern visible in precisely cut round brilliants. These images show the symmetrical pattern of eight hearts (viewed from the pavilion) and eight arrows (viewed from the crown) that results from exceptional optical symmetry. Not all round brilliants display this pattern; it requires a high degree of precision in facet alignment.
This is a feature GIA's standard reports do not include. If the diamond you are considering carries an IGI report with hearts-and-arrows images, it indicates the laboratory verified that the pattern is present and sufficiently well-defined to document. See Hearts and Arrows for what the pattern indicates about cut precision and why it matters.
Comments section
IGI reports include a comments field for observations beyond the structured grades. Treatment disclosures, laser inscription notes, and supplementary information appear here. The same rule applies as with GIA and HRD reports: read every line. A note about additional clouds, treatments, or surface-reaching inclusions can change how you evaluate the stone. See Comments on the Report for common entries.
Lab-grown vs natural report differences
Beyond the header colour coding, IGI's lab-grown diamond reports include several features that distinguish them from natural diamond reports:
- "Laboratory Grown Diamond" labelling appears in the title, in the body of the report, and often as a watermark or background text. There is no ambiguity about what the stone is.
- Report number series for lab-grown diamonds differs from the natural diamond series, providing an additional layer of identification.
- Laser inscription on lab-grown diamonds typically includes the letters "LG" before the report number, making identification possible even without the report in hand. See Report Number & Inscription.
These distinctions exist because the trade and consumer protection standards require clear separation between natural and lab-grown diamonds. IGI's implementation is thorough — if you are holding an IGI lab-grown report, you will know it.
Practical Tips for Czech Buyers
- Check the header first. Before reading grades, confirm whether the report covers a natural or lab-grown diamond. The colour coding and labelling make this straightforward.
- Translate "Ideal" to context. IGI's "Ideal" cut grade is the laboratory's highest designation for round brilliants. It occupies the same position in IGI's hierarchy that "Excellent" occupies in GIA's. The proportion boundaries differ, but the intent is the same.
- Do not equate IGI and GIA grades on natural diamonds. An IGI G colour on a natural diamond may correspond to a GIA H. Factor this calibration difference into price comparisons. For natural diamonds above approximately 30 000 CZK, a GIA report provides the most widely benchmarked grading standard. See Why Grading Differs Between Labs for the full analysis.
- For lab-grown diamonds, IGI is the standard. The grading calibration questions that concern natural diamond buyers are less commercially significant for lab-grown stones. An IGI report on a lab-grown diamond is appropriate and expected.
- Verify online before purchasing. Enter the report number on IGI's verification portal to confirm authenticity. This takes seconds and should be non-negotiable. See Online Report Verification.
Summary
An IGI Diamond Report contains the same core information as a GIA report: identification, measurements, 4Cs grades, finish, fluorescence, a clarity plot, proportions data, and comments. The key differences are terminological and presentational. IGI uses "Ideal" as its top cut grade where GIA uses "Excellent." Lab-grown diamond reports are visually distinct — different header colours, prominent labelling, and separate report number series — making confusion between natural and lab-grown reports unlikely for attentive readers. The substantive consideration remains grading calibration: for natural diamonds, IGI grades tend to run more generous than GIA's, and prices should reflect that difference. For lab-grown diamonds, IGI is the industry standard and its reports are the expected documentation. Verify every report online, read the clarity plot and comments with care, and when comparing stones across laboratories, let your eyes — not the letter grades alone — guide the decision.