Natural green colored diamonds are extremely rare. A dominant and natural green color will be present only in a small number of cut and polished diamonds. The stones with that color are so rare that not many have seen one, and even the ones who have, likely saw it inside a museum. You are not likely to find a natural green diamond at a mall jewelry shop. Even though these diamonds are very rare, some companies have a long history of selling them.
How the Green Color?
These diamonds got its color when these were underneath the earth, inside rocks containing small amounts of material like thorium or uranium. As these radioactive materials decayed, the emitted radiation penetrated the adjacent diamond crystal. When such radiation enters the stone, it can knock carbon atoms or electrons out of position in its crystal lattice. This change most strongly influences the diamond crystal’s outer layer. As a result, this color is usually present as a “skin” of little depth on the diamond crystal.
The gemstones that have a uniform green throughout them are very rarely found. The displacement of both carbon atoms and electrons deforms the lattice, and this alters how light travels through this gemstone. The said deformation causes the crystal to selectively take in much of the natural light that enters the rock, and to selectively transmit green wavelengths. This light travels back to the viewer’s eyes and gives the stone a green look.
The green color resulting from natural irradiation is considered the most common reason for the said color in diamonds. However, it can also occur due to flaws in the crystal structure of the stone.
Treated Green Diamonds
Inventive individuals always try to improve the color of gems to boost their value. This is done by mimicking the natural processes or by applying treatments which change the color.
Irradiation of the polished gems with a beam of low-energy electron is the most common lab treatment used to create the color in them. This particular treatment has been in use since the 1940’s and it can alter yellow or near-colorless diamonds to produce the green-colored ones.
Such diamonds have to always be retailed alongside a disclosure that it was color-treated, and the jewelers selling them should state the treatment method. So many customers prefer naturally-colored diamonds, so the green ones colored by treatment commonly retail for a considerably lower price than their natural counterparts.