Here follows a brief explanation of colours and other terms frequently used in the diamond industry

Canary diamond - A trade term for an intensely coloured yellow diamond. The yellow may be very slightly greenish or slightly orange, but the colour must be deep enough to become an asset. Such a diamond is called a fancy. A stone with colour greater than Z on the GIA colour scale.

Cape - A broad range of diamond colour grades that show a distinct yellow tint face up (except for small stones in the top part of the range). The best grade in the cape group is variously called top silver cape, top cape, light cape, fine cape or silver cape, depending on the grading system employed by the grader. In a three grade cape range, top silver cape, silver cape and cape are commonly used; top (or silver) cape, cape, and dark (or low) cape comprise another three-grade system. Any number of other combinations of terms are, or have been, used to cover the cape range in from two to five or more grades. Perhaps most commonly, cape series is used as the colour grade below top cape in the river-to-yellow system. For an approximate comparison of this grade to the GIA grading system and other not so common grading systems, please see the table at the end of this page.

Carbon spots - A term that is used in the diamond trade to refer to any black-appearing inclusion or imperfection in a diamond. Black inclusions may occasionally be graphite or small particles of another black mineral. Although many diamonds contain inclusions that appear black under ordinary lighting; dark-field illumination and magnification shows most to be caused by reflections from cleavages or included transparent crystals.

Champagne diamond - A trade term for a greenish-yellow or yellowish-green to brownish-yellow diamond that is not of sufficient depth of colour to be considered a fancy.

Chemical composition of diamond - Gem diamond is about 99.95% to 99.98% pure carbon. Common impurities, some of which may contribute to colour, include iron, silicon, calcium, magnesium, nitrogen, aluminium and boron.

Mêllée - In the trade, the term is used collectively to describe smaller brilliant cut diamonds, whether full cut or not. Usually, all small gemstones used in embellishing mountings, settings, or larger gems are called mêllée.

Milky diamond - A diamond that has a milky or hazy appearance. This condition is usually caused by clouds of exceedingly minute inclusions. Excessively fluorescent diamonds sometimes have a milky appearance in daylight.

Proportions - A term that meant originally the distribution of the mass of a fashioned diamond above and below the girdle. Use by diamond men has broadened its meaning to include the major facets that determine cutting quality; i.e. total depth as a percentage of the girdle diameter, table diameter, girdle thickness, facet angles, symmetry and even details of finish.

Rough diamond - A diamond in its natural state. An uncut or unpolished diamond.

Single cut - A simple form of cutting that has a circular girdle, a table, eight bezel facets, eight pavilion facets, and rarely, if ever, a culet. It is used mainly for small mêllée.

Solitaire - A term used to refer to a ring containing a single diamond or other gem.

Synthetic stone - A man-made stone that has approximately the same chemical, physical and structural properties as its natural counterpart. Many synthetic gem materials have been manufactured, but only a few are made commercially and cut as gemstones for the jewellery trade.

Top cape - An early trade term still used by some dealers to designate the diamond colour grade between crystal and cape in the river-to-light-yellow system. Diamonds in this classification have a yellowish cast that is visible to the unaided eye. For an approximate comparison of this grade to the GIA grading system and other not so common grading systems, please see the table at the end of this page.

Top crystal - An early trade name still used by some dealers to designate the diamond colour grade between Wesselton and crystal in the river-to-light-yellow system. Diamonds in this classification show a very slight tinge of yellow. For an approximate comparison of this grade to the GIA grading system and other not so common grading systems, please see the table at the end of this page.

Treated (or altered) diamond - A diamond that has been coated, fracture filled, laser drilled, or otherwise treated to improve or change its colour or appearance.

Wesselton - An early trade term still used by some dealers to designate the diamond colour grade between top Wesselton and top crystal in the river-to-light-yellow system. Only the faintest tint of colour is visible under ideal grading conditions.