What is a diamond colour-grading scale?

The GIA’s colour-grading scale is the industry standard for diamonds. It uses letters of the alphabet to help clearly define the range of colour appearance. The scale is based on the absence of colour and begins with the letter D, representing colourless, and continues with increasing presence of colour to the letter Z, or light yellow or brown.  Diamonds are colour-graded by comparing them to stones of known colour under controlled lighting and precise viewing conditions.

Fancy colour diamonds are those that fall outside of the normal colour scale and can be found in a range of colours. Brown and yellow fancy colours are most common but red, green, blue and even gray diamonds can be found. The different colours are due to the presence of various ‘impurity’ elements such as boron, carbon, hydrogen and also the effect of radiation on the carbon structure of the diamond.

Why is colour important?

However subtle, a diamonds colour value makes a big difference in the diamond quality and price. A chemically pure and structurally perfect diamond has no hue, like a drop of water, and has a higher value than one that has a brown or yellow tint. All things being equal, the more colourless a diamond is, the rarer it is, and this rarity will be reflected in its price. Grades D – F (colourless) are the rarest and therefore carry the highest price. Grades G – J (near colourless) have a subtle tint that is usually indistinguishable to the untrained eye. We recommend and only supply diamonds with a colour grade J and above.

See the below colour comparison tool provided by the GIA