In the gemological world, color actually means the absence of color—a diamond is graded highest on its colorlessness and lowest when it is brown or yellowish in hue.
Confused? We’ll clarify details about diamond color here.
Defining Diamond Color
A diamond that is truly colorless is actually quite rare. Due to exposure to natural gases and other chemical elements, most diamonds display some color tinge; some are faint and others are stronger.
During a diamond’s creation, the stone is exposed to such elements as boron, nitrogen, and sulfur. These chemicals interact with carbon atoms and result in the face of the diamond displaying shades of different colors.
Pressure and radiation during the creation process can also impact a diamond’s color.
About 98% of diamonds have some degree of yellow tinge due to impurities caused by nitrogen.
How are Diamonds Graded?
Diamonds are graded using the Gemological Institute of America (GIA) D-to-Z color scale and have been since the 1950s. This scale or chart is the industry standard when determining a diamond’s value.
Prior to GIA’s universal grading scale, there was no definitive way to describe diamond color. Prior scales used letters A-C, Arabic numbers, or Roman numerals. Still others used what were often misleading descriptions, such as “gem blue.”
The GIA D-to-Z scale measures diamonds on what is known as the Four C’s of gem grading:
- Carat size
Color is considered the second most important of the Four C’s because of the color’s impact on the diamond’s appearance. Cut is first because the cut of a diamond affects how much the stone sparkles.
For color, the D-to-Z range is as such:
- Colorless — D, E, F
- Near Colorless — G, H, I, J
- Faint — K, L, M
- Very Light — N, O, P, Q, R
- Light — S, T, U, V, W, X, Y, Z
Since truly colorless diamonds are rare, those with a D-F grading are considered more valuable than stones graded S-Z.
In order to get a true color determination, a stone is set against a master stone that displays the very minimum amount of color. The diamond is graded loosely, without being set so that any metal prongs do not impact the light passing through the diamond.
While some believe that diamonds are examined while face up, diamonds are actually graded when face down to avoid brilliance and light dispersion that can affect the color.
Fancy Diamond Color
Diamonds that display color beyond the brown or yellow Z grading on the GIA scale are considered fancy color diamonds.
Colored diamonds are rare. These would include those that are red, green, blue, or pink. The more intense and vivid the color, the rarer the diamond. Most rare colored diamonds are less than one carat.
To put this rarity in context: only about one in 10,000 diamonds mined from the earth is naturally colored.