The color of a diamond refers to the tone and saturation of color, or the depth of color in a diamond. The color of a diamond can range from colorless to a yellow or brown hue. A more colorless diamond is rarer and more valuable because it appears white and brighter to the eye. The most respected system used today for evaluating  diamond color was developed by the Gemological Institute of America, (GIA).

The GIA COLOR GRADE SCALE classifies diamond color into 22 grades from letter grade D (colorless) through letter grade Z (fancy color).

We recommend that you select a diamond that  is between (D) colorless and (I) near colorless. Diamonds in these ranges are considered to be whiter in appearance.

• Finest White, Select a diamond that is certified to have D or E color. Diamonds in these grades are in the range of colorless and will exhibit the brightest appearance.

• Fine White, Select a diamond that is certified to have F or G color. Diamonds in these grades exhibit no noticeable trace of color in normal face up viewing position and are more  affordable.

• White, Select a diamond that is certified to have H or I color. Diamonds in these grades cost less and usually appear white and exhibit a only slight trace of color that is difficult to see in most normal viewing environments.

Diamonds are assigned color grades by comparing them to diamonds with color grades which have been certified by GIA as master color comparison diamonds. The color grade of a diamond is determined by arranging the GIA master color comparison diamonds about one half inch apart, the lightest on the left and the others on the right in order of increasing darkness To accurately determine color, a diamond must be completely free of all dirt and oil. A diamonds color is best observed when viewed through the pavilion in the table-down position on a flat white diamond grading trough with line of sight parallel to the girdle plane.  A diamonds color grade is determined by moving it along the row of masters comparison guide diamonds until one seems to match. It is then placed on the side of the master, and then on the other side and compared carefully. If the diamonds color tone is lighter than the master, the next highest color grade is assigned. If the diamond is the same or only slightly darker, the grade of the master comparison guide diamond is assigned. To attain the most accurate analysis of a diamonds color it is recommended that a diamond be color graded in a white color free environment. Color grades are most accurate when evaluated in a darkened room using only the correct light source.  Filtered, cool white, balanced fluorescent light is best; unlike sunlight, it is nearly free of ultraviolet light.  The GIA GEM Diamond Lite is probably the best color grading light.

The Gran Colorimeter is a new instrument that is currently being used by many gem laboratories to electronically determine diamond color values. The Gran Colorimeter is currently marketed  by GIA's subsidiary Gem Instruments Corporation.