Diamonds generally increase in value as their colour moves from pale yellow to an absence of colour that promotes more reflection and dispersal of light. Even the slightest tinge of yellow or brown in a white diamond will decrease its value. White diamonds are graded on a scale that uses the letters of the alphabet to describe colour ranging from D (colourless) to Z (light yellow or brown).


Colourless diamonds are valued for their ability to reflect and refract white light to a greater degree than any other natural, colourless gemstone. The less colour or tint the higher the value, with totally colourless diamonds commanding the highest premiums.


When the degree of colour in a diamond becomes sufficiently noticeable, beyond the slightly tinted range, it is considered a coloured diamond. Once the degree of colour reaches a certain level of intensity it is classed as a fancy colour.

Coloured diamonds are prized for the beauty of their individual colours. Some fancy colours are extremely rare and command prices many times the value of those of the finest colourless diamonds.


S-Z - Noticeable Colour Yellow

These diamonds show increasing yellow or brownish tints and they are very off-white in colour.


N-R - Noticeable Colour
These diamonds show noticeable yellowish tints to the untrained eye.


K-M - Noticeable Colour Yellowish Tint

This colour does not show with smaller diamonds when they are mounted, but diamonds of half carat or more will show noticeable colour to the untrained eye.


J- Near Colourless
Colour is only slightly detectable, excellent in value.


I - Near Colourless 
Colour is only slightly detectable, excellent in value.


H - Near Colourless
These diamonds offer excellent value, with their colour only being noticeable when compared to diamonds of higher grades.


G - Near Colourless
These diamonds offer excellent value, with their colour only being noticeable when compared to diamonds of higher grades.


F - Colourless
Still considered colourless grade, these high-quality diamonds have only a slight colour as detected by a gemologist.


E - Colourless
These are rare diamonds that contain only minute traces of colour as detected by a gemologist.

D - Colourless
Absolutely colourless. This is the highest colour grade and these diamonds are extremely rare.

A note about fluorescence

Fluorescence is a property of some diamonds to emit visible light when exposed to invisible ultraviolet radiation. Fluorescence is detected by gemologist using special long wave and short wave ultraviolet lamp, and can manifest itself in daylight and some artificial lighting giving the diamond a bluish or milky appearance.


Though fluorescence lowers the value of a diamond, it can make it appear whiter and closer to colourless. Blue fluorescent colouring can actually improve the colour of a diamond by a grade or two while lowering its value. Fluorescence occurs in varying degrees of colour from a common blue to a rare yellow. Fluorescence is graded from None to Very Strong.


Key Points

  • Colour refers to a diamond's lack of colour, grading the whiteness of a diamond.
  • A colour grade of D is the highest possible, while Z is the lowest.


BUYER'S TIPS - Which colour should you choose?

  • When it comes to diamonds, most people find it very difficult (if not impossible) to tell the difference from one colour grade to another. Despite this, colour has a significant impact on the price of diamonds. Though purists prefer diamonds in the D to F range, you can find tremendous value and a colourless look by selecting diamonds in the G to I range.
  • If you are shopping on a budget or trying to maximize the size of your stone, consider J diamonds that combine affordability with near colourlessness.
  • Medium or strong fluorescence actually counteracts the slight yellow body colour of diamonds that are rated I colour or lower. As a result, these diamonds appear to be more white or colourless than they actually are. This gives the budget-conscious buyer the opportunity to purchase a lower-colour but whiter-looking diamond that offers an appearance that is comparable to a more expensive, higher colour diamond.