Diamonds are graded for colour on a scale from “D” or colourless, to “Z” or dark yellow. A chemically pure and structurally perfect diamond is completely transparent with no hue or colour. Almost no gem-sized natural diamonds are absolutely perfect. The colour of the diamond may be affected by chemical impurities and structural defects in the crystal lattice.

A “D” colour diamond is considered colourless–and the standard for a “white” diamond. Deeper tones, up to H, are often considered “near colourless”. Generally, the hue and intensity of a diamond’s colouration can enhance or detract from its value. Rare in nature, diamonds with deep yellow, pink or other significant colour have become especially prized as well.


Flaws inside a diamond are commonly referred to as inclusions. These imperfections may be crystals of a foreign material, another diamond crystal, or structural imperfections (tiny cracks that can appear whitish or cloudy). The number, size, colour, relative location, orientation and visibility of the inclusions can all influence the clarity of a diamond. Diamonds are graded from “flawless” (FL grade) to grades of VVS, VS, SI and “imperfect” (I grade).


The cut of a diamond describes how a diamond has been shaped and polished, from its beginning form as a rough stone to its final gem proportions. We often use the term “cut” to describe the shape of a diamond, as well as the quality of workmanship. A round shape is a favourite for engagement rings. Princess, emerald, pear, marquise and ovals are among the many other available shapes. Cut is also a measure of proportions, symmetry and polish. Together, these measures rate the cut facets from “Excellent” to “Poor”, regardless of shape.

The carat weight measures the mass or size of a diamond. One carat is defined as exactly 200 milligrams (about 0.007 ounces). The value of a diamond increases exponentially in relation to carat weight, since diamonds of larger sizes in gem qualities are rare.
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This guide provided by the Canadian Jewellers Association. www.canadianjewellers.com 

Images provided by American Gem Trade Association - www.agta.ca