Colour

Based upon the absence of colour, a chemically pure and structurally perfect diamond has no hue, like a drop of pure water, and consequently, a higher value. Colour is graded using a alphabetical grading scale; D-to-Z.  This diamond color-grading system measures the degree of colorlessness by comparing a stone under controlled lighting and precise viewing conditions.

Many of these color distinctions are so subtle that they are invisible to the untrained eye; however, these distinctions make a very big difference in diamond quality and price.