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GIA
Gemonological Institute of America
GIA's International Diamond Grading System

In 1953 GIA introduced it's Diamond Grading System, which today has become the international diamond grading standard. The procedures established by GIA determine the nature of each diamond and asses it's quality. The institute only grades natural diamonds and discloses any detected evidence of treatments on it's Diamond Grading Reports.

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THE FOUR C's

Carat Weight: Refers to the standard unit of weight for diamonds and other gemstones. Carat weight is measured at the GIA Laboratory using a highly precise electronic scale, rounded to the nearest hundredth of a carat.

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 from Flawles to l3.

Cut: Refers to how the proportions and finish of a diamond affect it's overall appearance and quality. Cut is graded on a scale from Excellent to poor and incorporates the diamond's brightness, fire, scintillation,weight ratio, durability,polish and symmetry.GIA only produces a cut quality grade for standard round brilliant diamonds that fall within the GIA O-Z colour range.

Proportions: Refers to a polished diamond's dimensions, facet angles and the relationships between them. For standard round brilliant diamonds, GIA reports the measurements of eight proportions: see diagram. For fancy shape diamonds (those other than standard round brilliants). GIA reports measured values for table size are girdle thickness and culet size are reported with word descriptions based on visual assessments.

Finish: Refers to the quality of a diamonds polish (the overall condition or smoothness of it's surface) and the symmetry (exactness of it's outline and the shape,placement and alignment of it's facets). Polish and symmetry are visually assessed and grade in one of the following categories: Excellent, Very Good, Good, Fair And Poor.

Fluorescence: Refers to the emissions of visible light from a diamond when subjected to ultraviolet radiation. On GIA 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. For Medium, Strong and Very Strong fluorescence, the colour of the fluorescence wil also be noted.

Note: a desciption of None refers to a range of fluorescence from indiscernible to very faint.

The recipient of this Report may wish to consult a credentialed jeweler or gemologist about the information contained herein. Since the colour, clarity and cut grades of a diamond often represent ranges of appearance, whenever possible, individuals should view the diamond rather than relying solely on the Report information before making purchasing decisions.