Diamonds are classified under 2 categories based on their color - White (or colorless) and Fancy-colored. While, former is predominantly white with varying shades of yellow, latter is intensely colored - like yellow, blue, pink etc. You may also read diamond color grading and fancy colored diamonds.
In this article, I have explained following different factors that affect color of white diamond:
Cut of Diamond
The way a stone is cut contributes a lot to its color. Correct proportion can enhance its color and brilliance.
But due to monetary aspect, not every diamond is cut in perfect proportion. The cutters’ main goal is to cut the stone such that it fetches the maximum value. So, if the rough is rare and valuable then cutter tries to save weight, thereby compromising on cut and its brilliance.
Presence of Fluorescence in white diamond
When diamond is exposed under ultra-violet (UV) light, it fluoresces as blue. Almost all diamonds fluoresce under ultra-violet light. This also helps in identification of diamond.
The UV light excites electrons in diamond which in turn leads to absorption of energy. Now, in order to return back to their stable state, these electrons need to release the absorbed energy. The absorbed energy is released in the form of visible blue light (sometimes of other color), which is called Fluorescence.
Fluorescence could be of faint to very strong intensity. Its intensity is graded on GIA grading scale as:
In rare situations, diamond continues to emit light for some time even after exciting light is turned off. This phenomenon is called Phosphorescence.
If a diamond glows strong blue under UV light, then it may look dull in sunlight. Diamonds with strong fluorescence may be worth up to 20 percent less than diamonds that do not fluoresce. Faint fluorescence that doesn’t fog the diamond is okay.
Technique like HTHP (High Temperature and High Pressure) is used to enhance the color of diamond. This technique was developed by GE. Through this technique, light brown diamonds are almost permanently made colorless, thus increasing the value of diamonds.
Irradiation method is
mainly used to change the color of diamond and enhance the color of
Synthetic Diamonds which are not naturally occurring are also created through these special techniques.
Mounting of the stone
Color of diamond is also influenced by the metal on which it is mounted.
For e.g. if a yellow tint diamond is mounted on a white platinum or silver or white gold, then the diamond will appear whiter and thus its value will increase. Whereas, if a colorless diamond is mounted on yellow gold, then diamond will appear slight yellowish leading to its decrease in value.
So, I will advise you that while buying diamonds do check on which metal it is mounted and how the mounting is influencing its original color.