Diamond Colour

Diamonds come in every colour of the rainbow, the rarity dictating the value. The ideal colour is the total absence of all colour, except where an intense hue is present. Yellow, pink, blue and green are rare while red is very rare. The GIA (Gemmological Institute of America) have set out a very precise scale of colour grading which is generally used by the jewellery trade. diamond colour grades are distinguished by letters of the alphabet, D is colourless though to Z which has a yellow tinge with various shaded in between. The more yellow tainted the diamond the less value.
It is commonly accepted that yellow is caused by an impurity of nitrogen molecules within the crystal structure, the more molecules the brighter the colour. Blue is caused by Boron and pink and browns by distortion of the crystal structure or hydrogen inclusions.