How to Read Your Certified GIA Diamond Grading Report

How to Read your GIA certified diamond - GIA report analysis

What is a GIA diamond grading report?

A GIA diamond grading report gives specific information about your diamond. It is important to understand all of the information on your diamond certificate relating to your stone. The following details relate to our main image. Each section of your diamond grading report provides key information about details such as the diamond colour, clarity and carat weight.

Replacement GIA certificate

Please refer to our main image for the numbered positions of each of the following diamond grading report features. 

1. Date

This is the date of examination when your diamond was assessed within the diamond grading laboratory.

2. Report Number

A unique number assigned to your diamond. Registered with GIA and searchable on their online report check database.

3. Shape and Cutting Style

The outline shape of the diamond and the pattern of the facet arrangement, referred to as the cutting style. The name of the diamond shape might vary from the generic shape name provided by a retailer. E.g. Princess Cut usually described on the GIA diamond grading report as ‘Square Modified Brilliant Cut.’

4. Measurements

The dimensions of your diamond. Listed as minimum diameter – maximum diameter x depth for round diamonds and length x width x depth for other fancy shapes of diamond.

5. Carat Weight

Weight of your diamond in carats. One carat is the equivalent of 1/5 of a gram. Recorded to the nearest 100th of a carat.

6. Colour Grade

An indication of the whiteness of your diamond. The GIA colour scale is used universally as an expression of the level of whiteness of a diamond. Ranges from D (whitest) down to Z.

Master set of diamond colour grade samples D - M

A set of colour matched sample stones used to demonstrate diamond whiteness grades

7. Clarity Grade

The relative absence of inclusions or blemishes. Graded on a clarity scale ranging from Flawless to Included in various sub-divisions. Diamonds are graded under 10x magnification.

8. Diamond Cut Grade

The cut grade of a diamond takes information from the appearance, design and craftsmanship, appreciating the proportions of the stone. A grade applied runs between Excellent to Poor. The cut grade can affect the price by as much as 40%.

9. Polish

The polish of a diamond is the smoothness of the diamond’s surface, assessed on a scale ranging from Excellent to Poor.

10. Symmetry

The exactness of the diamond’s outline, and shape and placement and alignment of facets, again based on a scale running from Excellent to Poor.

11. Fluorescence

Some diamonds exhibit fluorescence under Ultraviolet light. A description of ‘none’ represents a range of fluorescence from indiscernible to very faint. Strong fluorescence can result in lower prices with a noticeable ‘bluff’ appearance in certain conditions. Buyers seldom realise how fluorescence relates to the value of their diamond when viewing a GIA diamond grading report.

12. Inscription

Microscopically applied text, symbols, logos or the unique diamond grading report number applied to the girdle of the diamond.

Loose diamond photographed with GIA inscription

13. Comments

Additional identifying characteristics or features may be noted here, along with any treatments that might be detected.

14 . Proportion Diagram

Graphic representation of the diamond’s proportions.

15. Plotted Diagram

Shows a visual representation of your diamond, with blemishes and clarity characteristics illustrated as symbols, explained in the key.

16. Key to Symbols

Lists the characteristics and symbols shown on the plotted diagram if present.

17. GIA Colour Scale

Shows the GIA colour scale and relative positions of each whiteness grade within the scale.

18. GIA Clarity Scale

Shows the GIA clarity scale and relative positions of each clarity grade within the scale.

19. GIA Cut Scale

Shows the GIA scale of diamond cut grades for round brilliant cut diamonds and relative positions of each cut grade within the scale.

20. Security Features

Microprinting, security screens, watermarks, a two-dimensional barcode, a hologram and a sheet numbering safeguard report integrity and facilitate document authentication. Such strict security systems prevent fraud and tampering with GIA diamond grading reports.

21. QR Code

A two-dimensional barcode that when scanned verifies the data on the report against the GIA database of certified diamonds.

Mark Johnson

About Mark Johnson

Mark attended Liverpool University and went on to pursue a career in the diamond industry. After more than a decade working in polished diamonds, Mark moved to the Isle of Wight where he launched Serendipity Diamonds. He works most days from their busy Ryde showroom, photographing jewellery and writing for the Serendipity Diamonds website. Anyone interested can connect with Mark on Linkedin via the profile link.

Mark Johnson

About Mark Johnson

Mark attended Liverpool University and went on to pursue a career in the diamond industry. After more than a decade working in polished diamonds, Mark moved to the Isle of Wight where he launched Serendipity Diamonds. He works most days from their busy Ryde showroom, photographing jewellery and writing for the Serendipity Diamonds website. Anyone interested can connect with Mark on Linkedin via the profile link.