Coloration of diamond

Abstract

Colorless natural diamonds are rather rare. They are mostly of type IIa or pure type IaA (Welbourn 1994; Bienemann-Kuespert et al. 1967). Usually natural diamonds are colored. Many diamonds have a “dirty” unattractive coloration. The most common nonwhite colors of diamonds are gray, yellow, yellow-green and brown. Blue natural diamonds are the rarest. The main origin of coloration of diamonds is nitrogen in different aggregations. Colorless diamonds can be colored artificially by irradiation with α-particles, deutrons, protons, neutrons, electrons, γ-rays (Bienemann-Kuespert et al. 1967) or high-energy ions (*). In general, coloration of diamonds depends not only on their internal defect (color center) content, but also on the light under which and the substrate on which the diamonds are observed. Below the reasons for coloration of diamond are listed.