The formation of coloured diamonds

Nature's Rarest Gift



Coloured diamonds are made up of billions of carbon atoms, however if small amounts of other elements are incorporated into the crystal lattice, this can change the colour of a diamond.

Also known as fancy diamonds, coloured natural diamonds, are highly sought after and are even rarer than clear, colourless diamonds.

Discover exactly how these ultra-rare gifts from the earth are formed and the extraordinary natural processes that create coloured diamonds.

How are coloured diamonds formed?

Much like colourless diamonds, coloured diamonds were formed between 900 million to 3.2 billion years ago, deep below the earth’s surface, under intense heat and extreme pressure. They too are made up almost entirely of carbon atoms, however low levels of foreign atoms per million carbon atoms or structural defects can change them from colourless to coloured.

Discover below exactly how each different coloured diamond is formed.

Did you know

For every 10,000 colourless diamonds, only one is classed as a fancy colour diamond.

Yellow diamonds

The fancy yellow colour in natural diamonds comes from nitrogen within the crystal lattice. The way these groups of nitrogen atoms are arranged means that they absorb more light from the blue-end of the spectrum, and therefore give the stone its yellow appearance.

The amount of colour displayed, depends on the amount of nitrogen contained within the diamond’s crystal structure, however the more intense the colour is, the more expensive the stone.

Did you know

Less than 1 in 10,000 gem-quality diamonds are natural fancy yellow.

Blue diamonds

The colour blue comes from the chemical element boron trapped inside the diamond.

Although blue diamonds only need a tiny amount of boron to produce their colour, they are extremely rare, with only one in 200,000 natural diamonds showing a light shade of blue and even fewer displaying a deep, rich colour.

Green diamonds

A natural green diamond’s colour does not develop until the end of their journey to the earth’s surface. The colour comes from natural irradiation, usually caused by alpha particles. Absorbing red and yellow light causes the diamond to reflect a green hue, however this is usually confined to a very thin layer at the surface of the original rough diamond so it’s very rare that the green colour will be present throughout the diamond.

Did you know

Only a handful of natural green diamonds come to market each year.

Pink diamonds

Whilst the colour of most natural diamonds can be scientifically explained, the origin of pink colouration in diamonds still puzzles scientists. They believe that pink diamond shades are caused by plastic deformation, in response to extreme natural stresses during the diamond’s storage deep below the surface of the earth. This means that they didn’t actually start their growth process pink, making pink one of the rarest fancy coloured natural diamonds.

Brown diamonds

Brown diamonds, are the most common natural colour in diamonds. Their colour is caused by either structural defects in the diamond lattice or traces of nitrogen within the diamond lattice. This means that along with yellow diamonds, they are the only coloured diamonds whose colour is graded on the normal diamond colour scale.

Black diamonds

Black diamonds are not truly black. They contain numerous dark inclusions, meaning little light can pass through them, so this is what gives them their dark appearance. Common inclusions in black diamonds include graphite, pyrite, or hematite.

Whilst other natural coloured diamonds are transparent, the many inclusions in a black diamond means it is typically opaque and they will not exhibit the same fire and brilliance of a colourless or transparent coloured diamond.

Did you know

Black diamonds are the toughest of all the different natural diamond colours.

Red diamonds

Red are the rarest and therefore the most expensive of all the natural coloured diamonds. Although still uncertain, scientists believe that red diamonds get their colour the same way as pink diamonds, because of plastic deformation.

Did you know

Red natural diamonds are so rare that only around twenty to thirty are known to exist in the entire world and most are less than half a carat in size.

Imperfections creating beauty

Extremely sought-after and expensive, coloured diamonds are ultra-rare gifts of nature. Incredible processes in the diamonds have allowed for the formation of a stunning array of different coloured diamonds, from the light to the intense and the vivid. These atomic imperfections that have created beauty are a miracle of nature and will always be treasured; today, tomorrow and Forever.

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