Clear and colourless diamonds are a timeless favourite but who doesn’t like to pep things up once in while? Fancy coloured diamonds are the best bet when it comes to experimenting with colours on your jewellery.

How about a little trip into how diamonds get their colours? And maybe why they are so rare? Usually, every diamond has some colour in it. As per GIA’s diamond colour scale, D indicates a colourless diamond while Z stands for a light colour.

What are fancy coloured diamonds?

Diamonds which have a slight hint of colour do not quite qualify as fancy coloured diamonds. The saturation of colour in the stone has to be strong and obvious and this phenomenon is rare. 

Coloured diamonds should not be confused with gemstones. Both are very different in nature. Coloured stones take on different colours depending on many factors and so it’s hard to say how many are there. Here are a few:

Green diamonds

These are even rarer than clear and colourless diamonds. The mixing of a trace amount of nickel with carbon or natural radiation from other rocks under the Earth causes the green colour. 

Yellow diamonds

Diamonds with a yellowish tinge under the normal diamond colour scale do not qualify as coloured diamonds. If the yellow colour comes from the inclusion of nitrogen, then it is said to be a fancy coloured diamond.

Pink diamonds

Unlike the other colours, pink diamonds get their colour due to plastic deformation. This is a geological process in which immense pressure in the Earth’s crust causes changes in the diamond’s shape. As a result, there are also changes in the diamond’s atomic structure.

Blue diamonds

Some diamonds contain trace amounts of the element boron. But along with boron if there is a low level of nitrogen, the diamond turns blue. Some diamonds are also bluish grey but that is not related to boron.

Some stones like the Hope Diamond and the Oppenheimer Blue are two of the most valuable blue diamonds in the whole world.

Black diamonds

A black diamond is quite different from all the other fancy coloured stones due to the way it is formed. They are black as a result of iron clusters and graphite inclusions. They have a great metallic lustre but no fire and scintillation since they are opaque.

Given the number of inclusions in black diamonds, they are not as hard as a colourless rock. Depending on their hardness, they are classified as gem-quality stones or industrial diamonds.

What makes fancy coloured diamonds rare?

Diamonds as such are rare and expensive but the coloured ones are even rarer and pricier.

Coloured diamonds are those that have more colour, outside the D-Z scale. Pressure, natural radiation below the Earth or a change in the atomic structure influences the colour in diamonds.

Diamonds are made up of only carbon atoms and their chemical formula is C, also the symbol for carbon. They get their colour due to chemical impurities or a structural change.

It is mainly due to the pressure and heat that diamonds undergo certain changes in their atomic or molecular structure.