The diamond evaluation begins with the absence of colour. While most other gems are reviled for their brilliant colours, it is the absence of colour that increases the value of a diamond. A chemically pure and structurally perfect diamond has no hue and appears crystal clear. The colour scale begins with the letter D, representing colourless, and continues to the letter Z as the presence of colour increases. A truly colourless diamond, a D on the grading system, is extremely rare.
These colour distinctions, while invisible to the untrained eye, contribute significantly to the overall uniqueness of each diamond.
The D-Z diamond grading system, established by the GIA, is how each diamond receives its colour grade; the most popular grade is a near colourless rating since most diamonds do contain subtle hints of yellow or brown. These slight colour distinctions impact the overall quality and price of each diamond.