The colour of a diamond is one of the major factors influencing the price of diamonds. Most diamonds have at least a trace of yellow or brown body colour. With the exception of some natural fancy colours, such as blue, pink, purple or red, the colourless grade is the most valuable. If a diamond does not have enough colours to be called fancy, then it is graded in a scale of colours ranging from colourless to light yellow, “D” through “R”. A diamond with a “D” colour is Exceptional White. If the colour is more intense than “R”, it is considered fancy. Other things being equal, a fancy yellow diamond fetches more price than a light yellow diamond. Below table explains the description of various colour grades from “D” to “R”.

Alike clarity, in colour too we grade (+) and (-) to each set of colour like G, G+ and G-. All of them sums up to 45 different colour range. “Fancy Colour Diamonds” are graded using the depth or intensity of colour increasing from top to bottom. In addition to grading the colour of diamonds, other factors such as the Shade / Hue, inherent Fluorescence in a diamond, as also its colour, are factors that can have an influence on the overall colour of a diamond, and therefore critical to the grading. Colour Shade (Hue)

Grade Description
D Exceptional White
E - F Rare White
G - H White
I - J Off White
K - L - M Light Tinted
N - O - P - Q - R Tinted

At times, in a diamond crystal along with Carbon atoms Nitrogen or Boron atoms also form bonds which give rise to 'colour centres', which radiate a deeper shade across the diamond, giving it a Hue or Tone. Depending on the intensity of concentration at these colour centres, RGS grades 12 colour shades and all these sub-grades impact on the pricing.

Purity Description
WH White
OWH Off white
YL Yellow
BR Brown
YGL Yellowish Green
YLB Yellowish Brown
BRP Brownish Pink
PN Pink
PNB Pinkish Brown
GN Green
GKB Greyish Black
BL Blue

Factors other than 4c’s

Luster is basically the fire quality of the stone. Beside, some diamonds may have a little whiteness or cloudiness present in them. These are known as milky luster diamonds. Such diamonds are further classified into sub categories depending on the extent of the milky effect in them, using the below terminologies, we grade

Grade Description
Vg Best Luster Stone
Gd Slight Milky Stone
Fr Milky Stone

Emission of light by a diamond when exposed to ultraviolet radiation is termed as fluorescence. In better colours fluorescence reduces brilliance while in weaker colours it adds more brilliance.

In the RGS we grade fluorescence as follows:

Grade Description
Fl0 No fluorescence
Fl1 Faint fluorescence
Fl2 Medium fluorescence
Fl3 Strong fluorescence
FL4 Very strong fluorescence

Emission of light can be of different colour Depending on the nature and type of bonds that other elements form with Carbon atoms of a diamond crystal, fluorescence can be of different colours. Fluorescence colours like white, blue, yellow, orange and green are having direct impact on the overall colour and hence the pricing of a diamon