How to Read a GIA Report

A GIA report can look like a lot of numbers at first. Once you know where to look, it's one of the most helpful tools you have when choosing a diamond. The Gemological Institute of America (GIA) is an independent, nonprofit lab, and its reports describe a diamond's characteristics. Here's how to read one, section by section.

Report number and date

Every report has a unique report number and the date it was issued. You can enter that number in GIA's free online Report Check at gia.edu to view the report and confirm it matches. Many diamonds also have the report number laser-inscribed on the girdle (the thin outer edge), which a jeweler can show you under magnification.

Shape and cutting style

This tells you the outline (for example, round, oval or pear) and the faceting style (such as "brilliant" or "step"). See our diamond shapes guide for what each one looks like.

Measurements

Measurements are listed in millimeters. For a round diamond it shows the minimum and maximum diameter and the depth. For fancy shapes it shows length × width × depth. Dividing length by width gives you the length-to-width ratio, which tells you how long or chunky an oval, pear or cushion will look.

The grading results: the 4Cs

• Carat weight: the exact weight to two decimal places.
• Color grade: on GIA's D-to-Z scale.
• Clarity grade: from Flawless to Included.
• Cut grade: given for standard round brilliant diamonds, from Excellent to Poor. Fancy shapes don't receive an overall cut grade on most GIA reports, so polish, symmetry and proportions matter more there.

New to these terms? Our 4Cs explained simply guide covers them.

Additional grading information

• Polish and symmetry describe the quality of the diamond's finish and the precision of its facets, graded from Excellent to Poor.
• Fluorescence describes whether the diamond glows (often blue) under ultraviolet light, from None to Very Strong. In many diamonds it has no visible effect in normal light; in rare cases strong fluorescence can make a stone look slightly hazy, which is one more reason to see it on video or in person.
• Inscription(s) lists anything laser-inscribed on the girdle, usually the GIA report number.
• Comments may note things like additional inclusions not shown on the plot.

Proportions diagram

This drawing shows the diamond's profile with percentages like table % (the size of the top facet relative to the width) and depth % (the height relative to the width), plus crown and pavilion angles. These numbers help explain how the diamond handles light.

Clarity characteristics (the plot)

For many diamonds the report includes a map showing where inclusions are located, with a key explaining the symbols. Remember, these are seen at 10x magnification; many are invisible to the eye.

Lab-grown diamonds

GIA also grades laboratory-grown diamonds, and those reports clearly state that the diamond is laboratory-grown. Learn more in our natural vs. lab-grown guide.

A report is a description, not an appraisal

A grading report describes quality; it doesn't state a price or insurance value. For insurance, you'll want a separate appraisal.

Read one with us

Every diamond in our diamond search has a grading report you can view. If you'd like a friendly walk-through, bring any report to our Downtown Miami store and we'll go through it together.