Gem quality white diamonds have a color range from D-to-Z where D is colorless and Z has a yellow cast. As the yellow color increases, the value of the gem decreases. With fancy colored diamonds, as the color of the gem increases, so does its value. Accordingly, large, vivid fancy color diamonds are extremely rare and very valuable.
In the natural scheme of things, the color of most fancy color diamonds is muted rather than vivid and strong. The rarest fancy color diamonds are red, green, purple, and orange. Pink and blue fancy color diamonds are less rare, while yellow and brown diamonds are the most common fancy colors.
Blue colored diamonds get their color because some of the nitrogen atoms in there structure have been replaced by Boron atoms. As light passes through the diamond, the Boron atoms tend to reflect back to the viewer the blue wavelengths of the light spectrum. The greater the concentration of Boron atoms, the more intense or vivid is the diamond’s color. Naturally occurring blue diamonds are rare, highly prized and valuable. Blue diamonds are graded as follows:
1) faint, 2) very light, 3) light, 4) fancy light, 5) fancy intense, 6) fancy deep and 7) fancy vivid. The more intense the color, the more it costs.