Diamond color is rated by a standard set of guidelines given by GIA (Gemological Institute of America). A lettering system from D-Z is used to identify the amount of color present in each diamond. For your information, just to quench your curiosity, GIA used the lettering system from D so as to dissociate this standard from earlier systems. The descriptions of the lettering system are as given in the list below.

D – F:  Colorless. The highest the grade, which is extremely rare
G – J: Nearly colorless
K-M: Faint yellow
N – R: Very Light Yellow
V –Z: light Yellow
Beyond Z: is considered a fancy and exotic color, such as brown, blue etc.

Diamonds are evaluated in loose diamond (unset) within a laboratory controlled lighting booth, before mounting in the ring. To grade a diamond, gemologists often place it on a white background next to the master stone that has been previously graded. The laboratory or grader would possess a full set of master stones (usually consisting of 5 diamonds in two grade increments such as E, G, I, K, M) representing a range of color grade. After a diamond is set face up in a mounting, it is nearly impossible for even an expert gemologist to judge the difference between adjacent color grades such as between E-F color and G-H color from their naked eye, in either daylight or indoor lighting conditions. Since color differences can be so subtle, they are impossible to determine by the naked eye. Not limited by white color, there are some other fancy colors like steel gray, white, blue, yellow, orange, red, green, pink to purple, brown, and black. A different system is used to grade a fancy color diamond and the grading system consists of nine descriptors as listed below. For a fancy color diamond, the deepness or richness of the color is an important consideration.

• Faint
• Very Light
• Light
• Fancy Light
• Fancy
• Fancy Intense
• Fancy Vivid
• Fancy Deep
• Fancy Dark

For white diamonds, the less color in a diamond or the higher color rating, the more valuable a diamond becomes assuming all other factors are equal. Likewise, as the amount of color increases, the price of a diamond decreases (though this does not necessarily reduce the beauty of a diamond). While the difference in perceived color is very slight, the difference in cost can be over 50% between a colorless diamond and a near colorless diamond of one carat or more. Near colorless diamonds like G – I represent a good value for slight difference that is almost unnoticeable under the naked eye.

Tip for color consideration:  If we can’t tell the difference of two grades by naked eye, we rather save money for other attributes. In addition, the greater return of light from an excellent cut of diamond will far outweigh the minute difference in body color.

 See also how to budget on diamonds color.