My Cart

AGSL Diamond Quality Document

AGSL Diamond Quality Document A Diamond Quality Document, issued by the American Gem Society Laboratories (AGSL), is globally accepted and treasured by the jewelry industry as a document of a reliable and authentic diamond quality.

The AGSL uses a diamond grading system that positions cut, color, and clarity on a zero to ten scales, with zero signifying the rarest and mostly admired and ten indicating the least popular.

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 cut grade, zero being the rarest and much in demand where ten indicating the least desirable. There are three factors that determine a cut grade: Light Performance, Proportion Factors, and Finish
    • Light Performance - The overall look and image of a diamond when viewed from the top. Light Performance is one of the three factors used to determine cut.
    • Proportion Factors - Elements which determine a diamond's shape, including the proportions, weight ratio and strength. Proportion Factors are one of the three factors used to determine cut.
    • Finish - The general measure of a diamond's polish and symmetry. Finish is one of the three factors used to determine cut.
    • Polish - Rating the overall velvetiness of the diamond's surface.
    • Symmetry - Measuring the shape, arrangement and position of the diamond's facets in accordance to one another as well as the consistency of the design.
    • Color Grade - A grade of color, zero (D) being the most rare and popular and ten (Z) being the least favorite.
    • Clarity Grade - A grade of clarity, zero (FL/IF) being the most rare and popular and ten (I3) signifying the least favorite.
    • Carat Weight - Diamond weight is measured to the third decimal place.
    • Comments - A description of further diamond characteristics not already mentioned in the report. Also including fluorescence, this is categorized on a scale using the words inert, faint, medium, strong, and very strong.
    • Proportion Diagram - A drawing of the diamond's actual proportions.
    • Clarity Plot - A diagram of the approximate size, type, and position of any spots when viewed under a microscope.

Reading a Proportion Diagram

Proportion diagrams will classically include the following information:

  • Depth - The height of a jewel measured from the culet to the table.
  • Table - Located at the top of the diamond, the table is the biggest facet of a diamond.
  • Table - Located at the top of the diamond, the table is the largest facet of a diamond.
  • Girdle - Range of girdle thickness.
  • Culet - Appearance of the culet facet.