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Coloured Diamonds - What causes colour?

Coloured diamonds are amongst the rarest, most sought after gemstones. Although they have always been around, they started experiencing a resurgence when the pink Argyle diamonds marketing campaign took off. Most people are familiar with yellow and pink but did you know they come in various colours? Namely, red, pink, yellow, orange, brown, pink, green, blue and black.

While gem quality colourless diamonds generally decrease in value the more colour that occurs (Hence the scale from D- Z that all colourless diamonds are graded on.) the opposite occurs with coloured diamonds. All coloured diamonds have a similar scale to the 4C's however the colour intensity and overtones tend to be the overriding value factor. Coloured diamonds are cut to give the best intensity of colour possible from the crystal, therefore don't always adhere to the very specific proportions of colourless diamonds.



Large vivid fancy coloured diamonds are rare and valuable, however most coloured diamonds are muted in colour.

Diamonds are pure carbon, like graphite, however differ in their structure which gives diamond its amazing structural properties that we know and love.

Yellow and blue diamonds are caused by trace elements found within the atomic structure. Namely Nitrogen for yellow, and orange, and Boron for blue. Hydrogen has also been found to cause the grey colour found in some diamonds as well.

Red, pink and brown diamonds though, are caused by a deformation in the crystal lattice created by intense heat and pressure after the diamonds formation. This distortion displaces carbon atoms in the diamonds lattice altering the spectrum of light and therefore the colour seen by the human eye. The rarity of this phenomenon as well as clever marketing has seen pink diamonds meteoric rise in value. Although Argyle pinks are known to have the finest intense pink colour, they have been found in small paler quantities throughout history around the world.

Green is caused by exposure to radiation when the diamond formed. Most greens are quite muted in colour.

And lucky last, black, is caused by lots of inclusions naturally that fill the crystal to the point of opaqueness.

The lab grown process can now replicate these colours quite well however the rarity of the natural phenomenon is why the natural mined coloured diamonds are still worth so much more in value and rising.


If you're interested in coloured diamonds, natural or lab grown, contact me to discuss your next piece, or take a look at my ready to wear range that is available right now to ship.






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