Would you purchase a new car without knowing whether it had a four, six or eight cylinder engine? Of course not! Then why would you consider buying a diamond without knowing how well it has been cut? After all, most of the visual properties of a diamond are controlled by the Crown and Pavilion angles which are the primary surfaces within a diamond designed to reflect light. Of those two factors, the pavilion angle is the most critical factor but simply knowing what the measurements are only provides a glimpse into the potential visual performance of a diamond.

In order to determine the proportions rating of a diamond, you must know the specific measurements for the following factors:

• Table Diameter
• Crown Angle
• Pavilion Angle
• Girdle Thickness
• Culet Size

The specific combination of the Crown & Pavilion angle measurements have a direct effect on the visual performance of a diamond, together the crown and pavilion angles control 98% of the visual performance of a diamond. Simply assuming that a diamond has been cut to “ideal proportions” because it has the right combination of total depth and table diameter measurements is foolish, but unfortunately this is what many consumers are being asked to do by dealers who sell diamonds which have not been lab graded.  The term "proportions" simply describes the relationship between the elements or sections of the diamond design.  There is a rating system used within the industry to describe the proportions grade based upon the balance or ratio between each section of a diamond.

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