These occasions only happen very rarely. When all the conditions are perfect, it only takes a few days for carbon atoms to be transformed into rough diamond structures. However, it may take millions, or even billions of years before diamonds are formed and can surface on Earth to be discovered.
For natural color diamonds to be formed, in addition to the physical conditions necessary for forming diamond, trace elements interaction or radiation must also occur in the diamond crystal formation, making natural color diamonds extremely rare. Only one out of 10,000 diamonds made the trip to the Earth’s surface is naturally colored. Therefore, natural color diamond is truly one of a kind, and it is the world's most concentrated form of wealth.
Nitrogen imparts yellow or orange shades to a diamond. Boron imparts blue shade to a diamond ranging from deep blue to sky blue. Hydrogen produces unique violet hues. Tremendous pressure which abnormally compresses diamond's structure creates a red, pink, purple or brown stone. In many Argyle pink & cognac diamonds, evidence of graining can be seen at 10x magnification. Scientists believe it attributes to the tremendous pressures under the earth.
Whereas natural radiation impacting already formed diamonds over millions of years can give them a green hue.