888-565-7641
Diamonds, Engagement Rings and Fine Jewelry
Home > About Us > Quality & Value > Understanding an AGSL Diamond Quality Document
Understanding an AGSL Diamond Quality Document
A Diamond Quality Document, issued by the American Gem Society Laboratories (AGSL), is universally accepted and respected by the jewelry industry as a document of authenticated quality.

Features of the Diamond Quality Document Issued by the AGSL
The AGSL uses a diamond grading system that ranks cut, color, and clarity on a zero to ten scale, with zero signifying the rarest and most desirable and ten indicating the least desirable.

Diamond Characteristics Documented by the AGSL

    Shape and Style: Describes the diamond shape and cutting style.

    Measurements: Lists the diamond's dimensions in millimeters

    Cut Grade: A grade of cut, zero being the rarest and most desirable and ten indicating the least desirable. There are three components that determine a cut grade: Light Performance, Proportion Factors, and Finish.

    Light Performance: The overall appearance of a diamond when it is viewed from above. Light Performance is one of the three factors used to determine cut.

    Proportion Factors: Factors which determine a diamond's shape, including the proportions, weight ratio and durability. Proportion Factors are one of the three factors used to determine cut.

    Finish: The overall measure of a diamond's polish and symmetry. Finish is one of the three factors used to determine cut.

    Polish: Rating the overall smoothness of the diamond's surface.

    Symmetry: Measuring the shape, alignment and placement of the diamond's facets in relation to one another as well as the evenness of the outline.

    Color Grade: A grade of color, zero (D) being the most rare and desirable and ten (Z) being the least desirable. Assigned half points to accommodate all the grades of color.

    Clarity Grade: A grade of clarity, zero (FL/IF) being the most rare and desirable and ten (I3) signifying the least desirable. Look in the comments section for remarks about the finish.

    Carat Weight: Diamond weight is measured to the third decimal place.

    Comments: A description of additional diamond characteristics not already mentioned in the report, as well as fluorescence, which is rated on a scale and categorized using the words inert, faint, medium, strong, very strong.

    Proportion Diagram: A map of the diamond's actual proportions.

    Clarity Plot: A map of the approximate size, type, and position of inclusions as viewed under a microscope.

Reading a Proportion Diagram
Proportion diagrams will typically include the following information:

    Depth: The height of a gemstone measured from the culet to the table.

    Table: Located at the top of the diamond, the table is the largest facet of a diamond.

    Girdle: Range of girdle thickness.

    Culet: Appearance, or lack thereof, of the culet facet.

 
For More Information
Learn about our appraisals and other grading reports that accompany diamonds and fine jewelry from Blue Nile.

GIA Diamond Grading Report
GIA Diamond Dossier®
AGSL Diamond Quality Document
GCAL Diamond Certificate of Authenticity
Blue Nile Appraisal

Why Blue Nile?

Largest Online Retailer of Certified Diamonds
Forbes Favorite Online Jeweler Since 2000
Award-Winning Customer Service
888-565-7641
Why Blue Nile?

Discover Blue Nile

In the News
Read what's being said about Blue Nile in the news.
Customers Say It Best
Read how our customers feel about our performance.

Education & Guidance

Education & Guidance
Diamonds Platinum
Pearls Gold
Gemstones Silver

Contact Us
service@bluenile.com
888-565-7641
For phone orders,
please mention:
NCKY99
About Us
Blue Nile Advantage
Conflict-Free Policy
Careers
Investor Relations
Site Map
Services
Free FedEx® Shipping
30-Day Returns
Financing & Insurance
Refer a Friend
Sweepstakes
Blue Nile International
Blue Nile United States
Blue Nile Canada
Blue Nile United Kingdom
Newsletter and Offers
Receive special offers and
gift ideas from Blue Nile: