Coloured diamonds

Coloured diamonds are assessed by the character and intensity of their colour, not by how close they are to colourless. Yellow, pink, blue, green and brown are among the colours found in diamonds.

A different colour system

The D–Z scale is used for diamonds in the normal colour range, from colourless to a light yellow or brown tint. When the colour is distinct and desirable, a fancy-colour system is used. The laboratory then describes factors including:

• Hue: the dominant colour and any modifying colours.
• Tone: how light or dark the colour is.
• Saturation: the strength or depth of the colour.

Common intensity terms in GIA reports include Fancy Light, Fancy, Fancy Intense, Fancy Deep and Fancy Vivid. Always read the terminology in the context of the issuing report.

Natural, treated or lab-grown colour

Colour may be natural, altered through treatment or present in a lab-grown diamond. Appearance alone cannot establish which. A relevant grading report should state colour origin when that analysis is included in the report type.

Shape and setting

Cutters often choose a shape and facet pattern to emphasise colour. The metal and setting also affect how the colour appears. Compare the stone in its intended ring and under more than one type of light.

Check before buying

• Which report type accompanies the stone?
• Does the report state whether the colour is natural or treated?
• Is the diamond natural or lab-grown?
• Does the report number match the laboratory database?
• Is the centre diamond included in the displayed ring price?

Read about D–Z colour, grading reports and shapes.