The grade of colour refers to the absence of any colour in the diamond. High quality and chemically pure diamonds have no hue, just like a drop of water. The degree of colourlessness is measured by comparing stones with master set of stones of established colour value under controlled lighting and precise viewing conditions. Colour distinctions are usually subtle and invisible to the naked untrained eye but when visible is the colour of Pale Yellow. Experts suggest that human eye picks up the brilliance (cut) first and colour second.
The standard colouring system scale starts with the letter D which represents colourless and continues, with increasing presence of colour, to the letter Z.

D–E–F: Colourless
The highest colour grade that can be credited to a diamond is D. It denotes that the stone is completely colourless and such diamonds are extremely rare and demand the highest prices.
Diamonds with colour grades D-E-F are classified under the colourless category even though there are some differences between them. These variations can only be detected by a gemmologist and usually go unnoticed by the untrained eye. We recommend that such diamonds are set in white gold or platinum as yellow gold reflects colour negating the colourless appearance of the diamond.

G-H-I-J: Near Colourless
These diamonds are tabled as nearly colourless since they give away a slight hint of colour. Once mounted; they tend to be of excellent value in a diamond with little or no noticeable colour to the unaided eye. Within this range, the price tends to increase about 10-20% between each diamond grade.

K-L-M: Faint Yellow or Faint Brown
Starting from K, the pale yellow hue in the Diamond starts to get more noticeable to the naked eye. Set in yellow gold, the overall appearance of the jewellery is quite appealing to some buyers.
Due to its obvious colour tint, these diamonds are often found at half the price of a diamond of colour grade ‘G’. If the colourlessness of a diamond isn’t a priority, diamonds in this range turn out to be an excellent bargain.

N–R: Very Light Yellow or Very Light Brown and S – Z : Light Yellow or Light Brown
Diamonds in these ranges give away an obvious tint of yellow and range from faint yellow to light yellow with every grade. For most, these diamonds have too much colour when compared to the colourless diamonds. If you go further down the scale, the colours become more yellow and finally brown.