Blue diamonds are considered extremely rare. The Cullinan mine near Pretoria is the world’s only notable blue diamond producing mine.
The presence of boron will impart a blue shade to a diamond ranging from deep blue to sky blue.
Pure green diamonds are very rare since their natural green color comes from exposure to irradiated particles over eons of time.
Often confused with the green family, olive occupies a distinct, separate 3 dimensional color space adjacent to green. Bordered in this space by grey, brown, yellow and green, pure olive stones often have one or more of these modifiers to impart true uniqueness to its hue.
It is so rare that an orange diamond receive a color grading of pure orange, that many collectors have never seen one. More common, yet hardly abundant, are orange diamonds with a color modifier such as brown or yellow. Prized for their beauty and rarity, orange diamonds are one of the most sought after colors by prominent collectors.
The presence of nitrogen can impart orange shades to a diamond.
Red Diamonds are the rarest of the fancy color diamonds. In fact, they are so rare in nature that most jewelers and diamond dealers have never even seen a natural red diamond.