Diamonds are traditionally thought of as white or clear. But diamonds in fact do have color and this can be graded.

The most common grading scale for judging the color of a diamond is the alphanumeric scale provided below.

In this scale, the best diamond is the white diamond and the grading goes from pure white through to a yellow tint or color.

Here is the scale of the color grades a diamond will fall in:

D Pure White - the most prized colour
E Exceptional white - colourless group
F Excellent white - colourless group
G Good white - colourless group
H White - colourless group
I Slightly tinted white/ white when viewed from top
J Slightly tinted white/ commercial white
K Tinted white/ still acceptable white when mounted
L Tinted white/ needs yellow setting to look its best
M Slightly yellowish/Tinted colour-champagne
N Slightly yellowish/Tinted colour-champagne
O-R Yellowish/Tinted colour
S-Z Yellow/Tinted colour

Two thirds of all diamonds flouresce to some degree but how they do so depends very much on the type of ultra violet light. In the shop you will find the flourescense can be quite different to natural sunlight which explains why it is always important, when purchasing diamonds, to look at them in the light to which they will be exposed when being worn. Otherwise you might buy a diamond that presents quite a different, and to you, unsatisfactory appearance after you have walked out of the shop with it.

Strongly flourescent diamonds tend to take on a bluish tint in sunlight and this can affect the color grading also. The price of diamonds is dependent on their visual appearance so flourecence is a very inmportant factor here.

Sometimes a lower colored stone, as diamonds are commonly called in the diamond business. at the bottom of the scale can attract a higher price if it is strongly flourescent.

More information on clarity can be obtained here Color of Diamonds