Fancy color green diamonds are cut from rough diamonds that originate from mines in Brazil, South Africa, India, Australia, Congo, Ghana and Siberia. The green color is caused by the diamond’s exposure to the natural radiation in the earth such as from coming into contact with Uranium ore. When this happens, the diamond crystal's lattice structure is altered by the barrage of radioactive atoms enough to disturb the stability of the crystal's internal structure and produce a green coloration. Additionally, if heated by thermal processes within the earth, the diamond’s lattice structure will be further distorted causing further color change.
Fancy color green diamonds may have secondary hues and color modifiers such as yellow, gray, brown and in rare cases, blue. Green diamonds with no other secondary hues or modifiers are considered some of the rarest on Earth and depending on the diamond’s color intensity and purity can fetch extremely high prices. One example is the famous Dresden Green Diamond.
