The colour evaluation of most gem-quality diamonds is based on the lack of colour. A pure and structurally perfect diamond has no hue, similar to a drop of clear water, which gives a diamond a higher value. The D to Z colour-grading assess the presence or lack of colour by comparing to master stones, stones that are of established colour value.
Diamonds are known for being able to transmit intense light and sparkle. We think of a diamond’s cut as it's shape, either round, emerald, pear shaped. If a diamond’s cut grade is about how well a diamond’s facets interact with light, precise artistry and workmanship are needed to shape a stone so its proportions, symmetry and polish to deliver the magnificent return of light only possible in diamonds.
Natural diamonds are carbon exposed to tremendous heat and pressure, caused by volcanic activity in the earth. This process results in internal characteristics called inclusions and external characteristics called blemishes. Evaluating a diamonds clarity involves determining the size, relief, nature, and position of these characteristics and how this affects the overall appearance of the diamond, no diamond is perfectly pure, the closer it is to be pure, the higher the value.