How do diamonds get their colours?

Coloured diamonds contain impurities or structural defects within their chemical compositions. They are formed both in nature and in laboratory settings.

Natural coloured diamonds are created when foreign particulates are trapped during the crystallisation process. It affects and changes the usual chemical process, resulting in a beautiful, rare, expensive and exceptional diamond with unique colour.

Laboratories can create coloured diamonds by mimicking the natural process. They can also perform treatments like irradiation followed by intense heat to achieve vivid colour.

Red Diamonds

Red is the rarest and the most expensive diamond colour; they're made purely from carbon. When it is retrieved from underground and light passes through the irregular lattice, the unusual bending of the light causes the diamonds to reflect a ruby-like colour.

Blue Diamonds

Blue diamonds get their colour from boron. When this impurity is present, and the level of nitrogen is very low, it gives the diamond a blue colour.

Other blue diamonds are unrelated to boron. Nickel or high concentrations of hydrogen are the hypothetical causes of blue colour in some diamond.

Purple Diamonds

Pure purple is the result of an unusually high presence of Hydrogen and it's the second rarest colour of diamond. Scientists believed that they are formed due to post-growth plastic deformation while travelling from Earth's mantle to its surface via magma.

Pink Diamonds

Scientists speculate that the stress and strain experienced by rough diamonds when they're in the Earth's mantle causes the diamond's lattice to be distorted. This distortion creates graining and pink colour zones to occur within the diamond.

The pink diamonds in Sydney are one of the nature's rarest diamonds, making it a much sought-after centerstone for any white gold engagement ring, wedding ring or jewellery set.

Yellow Diamonds

The yellow colour comes from the inclusion of nitrogen that's similar enough to carbon atoms that they easily take place in the formation process. They're very common, but the most vivid are mined in South Africa.

Yellow diamonds that aren't vivid enough are "enchanced" with blue colouring, in the hopes of passing the diamonds as colourless.

Green Diamonds

Some green diamond have a trace amount of nickel in their carbon. Most of the colouration is because of the natural radiation from rocks in close proximity to it, that traps electrons to create a green surface. Some of the natural green is lost during polishing due to the location of the coloured portion which is mostly in its outer layer.