Diamonds come in a variety of colours, some of them highly prized (pinks, blues, even yellow). In a white diamond, however, the presence of a yellow tint will lower the price of a diamond. The less body colour in a white diamond, the more true colour it will reflect, and thus the greater its value.
Diamonds are assigned a colour grade by the GIA in a viewing environment specially designed to eliminate colour from surrounding surfaces as well as the light source itself.
This allows the colour of the diamond to be accurately measured. Minor differences in diamond colour detected in this environment are very difficult, if not impossible, to detect in a normal environment.
The diamond industry has adopted the GIA diamond colour scale; almost every diamond sold today is rated using the GIA colour scale, whether it was actually certified by the GIA or not.
Colourless D E F
While there are differences in colour between D, E, and F diamonds, they can be detected only by a gemologist in side by side comparisons, and very rarely by the untrained eye.
D-F diamonds should only be set in white gold / platinum. Yellow gold reflects colour, negating the diamond's colourless effect.
D to F
Near Colourless G H
While containing traces of colour, G-J diamonds are suitable for a platinum or white gold setting, which would normally betray any hint of colour in a diamond.
Because I-J diamonds are more common than the higher grades, they tend to be a great value. An I-J diamond may retail for half the price of a D diamond. Within the G-J range, price tends to increase 10-20% between each diamond grade.
G to H
Beginning with K diamonds, colour (usually a yellow tint) is more easily detected by the naked eye. Set in yellow gold, these warm coloured diamonds appeal to many, and are exceptionally valuable.
Due to its perceptible colour tint, a K diamond is often half the price of a G diamond.
I to J
K to M
Very Light Colour
Diamonds in the N-R colour range have an easily seen yellow or brown tint, but are much less expensive than higher grades.
For almost all customers, S-Z diamonds have too much colour for a white diamond.
N to R
S to Z
Fluorescence is the visible light some gemstones emit when they are exposed to invisible ultraviolet (UV) rays. In natural diamonds, blue is the most common colour of fluorescence, but other colours may be visible.
On a GIA Diamond Grading Report, fluorescence refers to the strength, or intensity, of the diamond’s reaction to long-wave UV, which is an essential component of daylight.
Colour becomes much harder to detect once a stone is set in a ring and placed in an environment that contains colour (as opposed to the all white background used in diamond colour grading). For instance, an H colour diamond may look as colourless as a D when set in a ring under normal lighting conditions, especially if the two are not compared side by side.
Another factor that affects a diamonds's apparent colour is the colour of the mounting itself. Yellow gold makes slight amounts of yellow in a diamond less obvious, while white metal mountings make the colour in yellow diamonds more apparent.
The vast majority of untrained observers (and many gemologists) cannot distinguish a colour grade from the one just above or below unless the diamonds are compared side by side in a controlled environment.
Colour becomes more important as carat weigh increases. Colour is easier to perceive in a larger diamond, just as a carafe of white wine shows more colour than a single glass.