The 4Cs - Colour
The 4Cs of diamond quality - Colour, Cut, Clarity and Carat Weight - were established by internationally renowned leader in gem education, research and laboratory services, the Gemological Institute of America (GIA). GIA is an independent, non profit organisation and the 4Cs were created to provide a universal standard of diamond quality to aid consumers in understanding the collective impact of the 4Cs on a diamond's value.
When assigning a colour grade, GIA graders use standardised environments and master diamond sets to ensure every grader objectively and accurately assigns a colour grade. Each diamond is independently evaluated by multiple graders and isn't given a final colour grade until there is consensus.
The GIA colour scale (shown below) starts at D, representing a colourless diamond, and ends at Z. Diamonds at the lower end of the scale will have a noticeable yellow or brown tint, but are not fancy colour diamonds.
To us, colour (or lack of) is one of the most characteristic features of a diamond and one that is easily visible to the untrained eye. That's why we only stock colourless diamonds (D), emitting a beautiful, clean bright white light.
GIA DIAMOND COLOUR GRADING SCALE
Drag the gold slider through the GIA colour grading scale to see the transition from colourless diamonds (D-F) to diamonds emitting a faint yellow colour.
GIA have produced a video on colour grading, which is highly recommended and provides a brilliant insight into the grading process.