Diamond Education
How to Read a Diamond Grading Report
A grading report from an independent laboratory such as GIA or IGI documents a diamond’s identity and characteristics. It is the most important document to review before choosing a diamond.
A grading report from an independent laboratory such as GIA or IGI documents a diamond’s identity and characteristics. It is the most important document to review before choosing a diamond.
Report number
Verify online with the lab
Shape & cutting style
e.g. Oval brilliant
Measurements
Length × width × depth, mm
Carat weight
Weight, not size
Color · Clarity
Graded ranges
Cut (where graded)
Varies by lab and shape
Polish · Symmetry
Finish quality
Fluorescence
Response to UV light
Origin
Natural or laboratory-grown
01
What a report records
Reports typically list shape and cutting style, measurements in millimeters, carat weight, color, clarity, and — where the lab grades it — cut. They also record polish, symmetry, fluorescence and proportions, and whether the diamond is natural or laboratory-grown.
Many reports include a clarity plot mapping characteristics, and note any detected treatments.
02
Report numbers and inscriptions
Each report carries a unique number. Many diamonds also have that number laser-inscribed on the girdle, visible under magnification. You can confirm a report through the issuing laboratory’s online verification service.
03
Grading practices differ
Laboratories apply their own standards and report formats. Compare diamonds by their full reports, and be cautious of comparing a grade from one lab directly with a grade from another.
04
A report is not an appraisal
A grading report describes characteristics and origin. It does not state a monetary value. An appraisal, typically used for insurance, is a separate valuation document prepared by an appraiser.