The Diamond Certification Laboratory of Australia (DCLA)

Lower part, or ‘bottom half’, of a diamond below the girdle.

Angle measured between the girdle plane and the pavilion main facets.

Distance in millimeters or percentage from the girdle to the culet.

Pavilion depth expressed as a percentage of the diameter. Pavilion depth is an extremely important proportion to the brilliance of a diamond; diamonds with a pavilion that is too deep will have a nailhead, while diamonds with a pavilion that is too shallow or flat will have a fish eye.

Kite-shaped facets clustered from the culet and extending to the girdle.

Diamond cut or shaped into the outline of a tear-drop or a pear, with a rounded head tapering to a point.

Phenomenon that causes some diamonds to continue “glowing in the dark,” after a light source is removed. Phosphorescence is much more common in synthetic diamonds than in natural diamonds.

A coloured diamond with a natural pink body colour. Pink must be the predominant colour, but it may be modified by shades of purple, orange, and yellow. The colour in natural pink diamonds is created by irregular crystal structure. Some pink coloured diamonds with sufficient saturation fall into the valuable fancy pink colour category of diamonds.

Very tiny diamond crystal inclusions that are too small in size to distinguish their individual shapes. One pinpoint looks like a small “dot” under 10x magnification. Clusters of pinpoints create a cloud.

Type of diamond blemish that appears as a tiny opening or indentation on the surface of a diamond. Large pits are called cavities. Pits affect the polish grade of a diamond.

Diamond facet with numerous pits. Pitted facets affect the polish grade of a diamond.

Diagram of the approximate relative size, location, and type of internal inclusions and external blemishes of a diamond. A plotting diagram is often used for identifying a particular diamond.

Term for one hundredth of a carat. For example, a fifteen-point diamond weighs 0.15 carats. It could also be called a fifteen “pointer”.

Qualitative analysis of the overall surface condition of a diamond. The quality of polish is determined by the care put in by a polisher when finishing a diamond, and is important to the brilliance and scintillation given off by a diamond.

Lines left on the surface of the diamond which are visible under magnification, normally removed during the final diamond polishing process. Polish lines can affect the polish grade of the diamond.

Describes the girdle of a diamond that has been fully polished smooth and clear around the entire perimeter. Step cut diamonds such as emerald cut and baguette cut diamonds usually have a polished girdle, and some brilliant cut diamonds may have polished girdles as well.

Diamond cut or shaped into a square or rectangle. Princess cuts combine features of both step cut and brilliant cut diamonds.

Qualitative analysis of the overall proportions on a round brilliant cut diamond. Fancy shaped diamonds are not proportion graded; unlike round cut diamonds, there is no defined range of proportion standards for fancy shapes.

Relations between the dimensions and angles of a finished diamond. Examples of specific proportions are table size, depth percentage, and crown angle. Proportions are extremely important to the beauty, brilliance, and life in a diamond. Click here to learn more about proportions on a diamond grading report.