Color refers to the degree to which a diamond is colorless.
The farther from colorless that a diamond's grade is, the less rare and therefore less valuable it is.
Diamonds are graded on a color scale established by the Gemological Institute of America (GIA), which ranges from D (Colorless) to Z.
Icy winter whites (D-I) look stunning in white gold or platinum. Warmer colored diamonds (J-Z) are more desirable when set in yellow gold.
Color differences can be very subtle and grading is done under controlled lighting and compared against a ‘master’ for accuracy.