Many people are unaware that colored diamonds other than black exist. When in fact, diamonds come in various hues of the rainbow. The most common colors of colored diamonds are Yellow, Blue, Black, Green, and Pink. Red is the most rare colored diamond and in fact, it is so rare that researchers aren't even sure of how they gain their color.
However, researchers have came to a conclusion on how the other colored diamonds obtain their color.
Yellow diamonds appear to be yellow based on how much nitrogen is within the crystal structure.
Blue diamonds typically depend on the presence of boron in the crystal structure to get their color, but can also become blue due to radiation exposure or high amounts of hydrogen.
Black diamonds get their color from large amounts of inclusions containing graphite, pyrite, or hematite with a combination of cleavages or fractures that are stained.
Green diamonds gain their color by radiation caused by radioactive rocks near diamond deposits. Green diamonds are very rare as a natural process. They can also become green artificially by irradiation of the stone.
Pink Diamonds are caused by color centers selectively absorbing light with in the crystal system.
GIA laboratories have a colored diamond grading system and the GIA can evaluate them for origin.
GIA is the worlds foremost authority in Gemology and the information provided in this blog was resourced from them.