Grades of Colour

The science behind diamonds’ natural colour wheel.

Diamonds - Grade of Colour
Jewellery // Catanach’s       Image // Tord Johnston

Grading System

The industry’s most widely accepted grading system is GIA’s D to Z colour grading scale. The scale begins at D, which represents colourless diamonds, and as the scale works through the alphabet there is a gradual increase in the presence of colour down to the letter Z.
Most of these colour distinctions are so subtle that they are undetectable to the untrained eye. However, these distinctions make a very significant difference in the diamond quality and price.

The Scale

Colourless: D-F
While there are differences in colour between D, E and F diamonds, they are invisible to the untrained eye and can only be detected by a gemmologist. D-F diamonds should ideally be set in white gold/platinum, as yellow gold reflects colour and will negate the diamond’s colourless effect.

Near Colourless: G-J
Most diamonds underneath a colourless grade aren’t suitable for platinum or white gold settings as it betrays any hint of colour within the diamond, G-J grade diamonds
possess such a miniscule tint of colour that they are an exception to this rule. I-J diamonds are more common than the higher grades and offer great value for customers.

Faint Colour: K-M
From K classifications diamond colour begins to be more easily detected by the naked eye. However, if the diamond has a yellow tint and is set in gold the diamond will reflect a warm colour, which can be very appealing.

Very Light Colour: N-R
Diamonds in this range have easily visible yellow or brown tints, but are much less expensive than higher grades.

Light Colour: S-Z
For most people S-Z diamonds contain too much colour to be a desirable white diamond.

Z-GRADE & FANCY-COLOUR
It is important to note that Z-grade diamonds are not considered fancy-colour diamonds. For a diamond to be classified as fancy-colour the diamond’s natural colour must be outside the normal colour range. The general rule is that fancy-colour diamonds exhibit a colour other than yellow or brown, or are more yellow/brown in colour than a
Z-grade stone.

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