The wonderful thing about diamonds is they come in so many choices of shapes, sizes, cuts and colors, so you can find the perfect gem to express your style and tastes. Diamonds come in a wide range of colors, from sparkling clear to deep blue.
The color of a diamond is determined by the chemical makeup of the gem as well as structural impurities. A transparent diamond with no tint of color has no defects or impurities and is very rare. It will have a high amount of sparkle and shine.
Diamonds that range from clear to off-white or brown are called white diamonds. White diamonds are graded on color with a system ranging from D, which is completely colorless, to Z, which is a pale yellow or brown color.
Diamonds also come in a wide range of colors, including pink, blue, red, black, orange and purple. Red diamonds are the rarest colored diamonds. Colored diamonds have impurities which cause tints of color. Despite their impurities, colored diamonds are extremely valuable as they are rare. Colored diamonds – also called fancy colors – make up less than 2 percent of all diamonds.
Fancy color diamonds have an intensity of color that falls outside of the D to Z range of white diamonds. Colored diamonds are ranked by color hues, with a list of 27 possible options, ranging from Reddish-Orange to Purplish-Red and Black Diamonds. Then the gems are further described by saturation level, with nine options: Faint, Very Light, Light, Fancy Light, Fancy, Fancy Dark, Fancy Intense, Fancy Deep and Fancy Vivid.
The Gran Colorimeter is a tool that diamond experts use to measure color. The device can measure white diamond grades as well as colored diamonds and their intensity levels. The colorimeter is fairly accurate, measuring within ½ of a color grade on loose stones and within 1 color grade on mounted gems.
image source from http://www.hydeparkjewelers.com/natural-color-diamonds.aspx