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AGSL 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. 


AGSL Diamond Quality Document

 
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. 



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