The most valuable diamond is the one without color.

Such colorless pieces are extremely rare; mostly what is termed as colorless is faint yellow or with brown tints and considered the normal color range. So, contrary to the use of words, not all white diamonds are colorless.

Once again, we turn to GIA to provide the norm on colors; the grades range from D to Z and since 1950 are the universally accepted codes.

GIA Color Grade Scale
D - F	G - J	K - M	N - R	S - Z
Colorless	Near Colorless	Faint Yellow	Very Light Yellow	Light Yellow

Measuring the Color

Since the color difference is so narrow with no distinct color and one mostly merging into the other, color in white diamonds is measured by making comparisons with a set of 'master stones' of known color; the one on top of the range is E-color so that any diamond with a better color automatically rates a D.

Likewise, a color better than G is assigned an F color grade through a process of progressive elimination.

With technological advances, the 'Colorimeter' is frequently used to arrive at the exact color grade. This is a dedicated computer working on the principle of a fiber optic light to digitally measure the color of a diamond. Being 98% - 99% accurate, it forms a valuable, unbiased gradation tool. However, the results of this instrument are always compared to the traditional 'master stones' to ensure accuracy of the diamond's color grade.

Flourescence

Some diamonds are known to give off a glow under strong ultraviolet light which is called Fluorescence. Colorless diamonds have no effect by fluorescence other than appearing slightly milky at times but the faint yellow and near colorless may look whiter with some 'blue fluorescence'. And some clients prefer this unique effect.

Why is a diamond's color grade important?

Since diamond is a like a prism that reflects light and this feature is exclusive to the stone, color becomes an important consideration in evaluating the stone. The light entering the diamond is split into spectral colors, which are then reflected and seen by us as color flashes, called fire. This is most effective in the absence of any color in the stone because the presence of any natural color in the diamond filters the light and reduces its fire and brilliance.

In conclusion, the diamond with no or less color is more valuable than one with any degree of color and therefore lower down on the color grade scale. To illustrate, the relative values of one carat, VS1 clarity, and 'Ideal' cut round diamonds at different color grades are given below:

GIA Color Grade Scale and Approximate Value
D - F	G - J	K - M	N - Z
$8,700 - 7,800	$7,200 - 4,700	$4,300 - 3,200	Not sold by Wonder Jewelers