The diamond color evaluation of most gem-quality diamonds is based on the absence of color. A chemically pure and structurally perfect diamond has no hue, like a drop of pure water. The D-to-Z diamond color-grading system measures the degree of colorlessness by comparing a stone under controlled lighting and precise viewing conditions to a master set of stones with known color grades. The scale begins with the letter D, representing colorless, and continues, with increasing presence of color, to the letter Z. Many of these color distinctions are so subtle that they are invisible to the untrained eye. Other factors being equal, the whiter the diamond the more desirable and valuable it is.
D – E – F Extremely white, colorless
G Very white and very attractive
H White, very attractive
I Very, very slight hint of yellow, considered white
J Noticeable yet slight tint of yellow
K – Z Increasing yellow tint as scale moves towards Z
Note: I acquire the whitest and best cut stones on every project I do, as far as the budget allows