An ADGL Diamond Grading Report will confirm the exact characteristics of the diamond under examination.

The stone is colour and clarity graded, weighed and scanned to reveal all the relevant angles and dimensions which determine the quality of cut.

In addition the stone is plotted with the internal and external inclusions and blemishes.

Finally, the girdle of the stone is inscribed with the initials ADGL and the certificate number. This inextricably links the stone and certificate together, thus avoiding any disputes that may arise in the future.



Explanation of terms on the Certificate

Carat Weight: Refers to the standard of unit of weight for diamonds and other gemstones. Carat weight is measured using a highly accurate electronic scale, rounded to the nearest hundredth of a carat.
The Ogi Proportion Scope also calculates the weight from all the measurements and dimensions of the stone. Although this can often be more accurate than the carat scales the scales are considered to be the definitive measurement

Colour: Refers to the GIA Colour Scale, which extends from D (colourless) to Z (light yellow or brown). Colour grades are established by comparing each diamond to a set of master comparison diamonds in a standard lighting and viewing environment. Each letter grade represents a range of colour.

Clarity: Refers to internal features (inclusions) and surface characteristics (blemishes) within or on a diamond when viewed with 10x magnification under standard viewing conditions. The GIA Clarity Scale includes eleven clarity grades ranging from Flawless to I3.

Cut Proportions: Considered to be one of the most important of the 4 C’s, cut refers to how the proportions and finish of a diamond affect its overall appearance and quality. Cut is graded on a scale from Excellent to Poor and incorporates the diamond's brightness, fire, and scintillation. ADGL uses the GIA Facetware system for determining quality of cut.

Cut is not to be confused with the shape of the diamond.

Proportions: Refers to a polished diamond's dimensions, facet angles and relationships between them. ADGL reports the measurements of nine proportions for both round brilliant and fancy shape diamonds.

Polish: Refers to the quality of a diamond's overall condition or smoothness of its surface.

Cut symmetry: Refers to the diamond’s exactness of outline; and the shape, placement and alignment of its facets.

Polish and Symmetry are visually assessed and graded in one of the following categories: Excellent, Very Good, Good, Fair and Poor.

Fluorescence: Refers to the emission of visible light from a diamond when subjected to ultraviolet radiation. On ADGL’s Diamond Reports, fluorescence is a description, not a grade. The terms for describing the strength of fluorescence are: None, Faint, Medium, Strong and Very Strong.

Note: a description of ‘None’ refers to a range of fluorescence from indiscernible to very faint.

Since the colour, clarity and cut grades of a diamond are varied in combination, whenever possible, individuals should view the diamond rather than relying solely on the Report information before making purchasing decisions. The certificate is a document which details the hard facts about the diamond, but ultimately it is the combination of all the angles, dimensions, colour and cut which makes a diamond a beautiful gem or not.