How Is Colour Determined?

When it comes to determining the value of a fancy colour diamond, colour is the most influential factor. Colour is ascertained based on the following attributes:

Hue: Hue refers to the dominant colour of the diamond. It can be affected by the presence of 'modifiers' or 'tints', which are additional hues within the stone. The hue of a stone with no tints present is described as a pure primary colour, for example, 'a pink diamond'.  If this pink diamond had a purple tint within it, it would be described as 'a purplish-pink diamond'.

Tone: Tone refers to how light or dark a stone appears.  This is determined by how much brown, black, grey or white is present within it.

Saturation: Saturation refers to the strength or intensity of the hue or main colour within the stone.  The saturation of lightly toned diamonds can range from ‘light’ to ‘intense’ to ‘vivid’ in description.  For darker diamonds, descriptions range from ‘dark’ to ‘deep’.

Distribution: Distribution refers to how evenly spread the colour is throughout the diamond.

Professional gemologists at gemology labs assess these variables and produce a natural coloured diamond grading report, which is used to value the natural coloured diamond.


The 4C’s are also assessed on coloured diamond however, in the GIA grading report the colour aspect is detailed further by describing:

  •   Origin: Describes whether the stone is a natural or treated colour.
  •   Grade: Hue, tone and saturation are all considered when grading colour. The GIA uses the                 following grades to identify colour intensity: faint, very light, light, fancy light, fancy, fancy     intense, fancy vivid, fancy dark, fancy deep.
  •   Distribution: how evenly spread the colour is throughout the diamond.


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