Color is the second most important aspect when choosing a diamond. When looking at a diamond, the human eye notices the diamond's cut first and its color second. Color becomes especially important when considering diamonds of larger size, since the additional light reflected from a larger diamond can make the color more noticeable.
Diamond color is one of the most important factors to consider, as it is noticeable to the "naked" eye. A diamond's color is graded on an alphabetical scale from D-Z, with D being absolutely colorless and Z being light yellow. Beyond "Z", a diamond is considered to be a "Fancy" color. Although many diamonds appear to be colorless, many of them have at least a hint of body color.
The actual diamond color grading process is done by a side-by-side comparison under controlled conditions. The un-graded diamond is compared to a collection of certified round diamonds of known color. These certified comparison diamonds are called master-stones and each color represents the least amount of color in its color range. Accurate color grading is extremely dependant on the master-stones, the environment, and the grader.
Some diamonds may display fluorenscence. What is Fluorescence? Diamonds often emit a color reaction when subjected to ultraviolet light. Diamond fluorescence is graded on a scale from “None” to “Very Strong.” Most often diamonds fluoresce a blue color, however other colors are possible. If the fluorescence of a diamond is stronger than “Faint”, most grading laboratories will note the color of the fluorescence on the report. Fluorescence can add an interesting quality to a diamond and can actually help diamonds look nicer when they have a lower color grade as in K- M, however, a very strong fluorescence can affect its value.
When buying a diamond, take into consideration that it is often very difficult to detect the difference between a colorless diamond (D-F) and a near colorless diamond (G-I), especially when it is mounted in jewelry. Diamonds with a J-Z color grade usually have yellow shading that can be detected by the naked eye. However, a well cut stone with good proportions and lower color will still release the brilliance and fire you expect from a diamond.