Most diamonds seen alone appear white but most have a hint of colour, mainly yellow. Diamonds with no trace of colour at all are extremely rare and the closer they are to no colour, the more rare and valuable they will be. To the untrained eye, it is usually very difficult to tell the differences in diamond colour.
Colour is represented by a lettered scale from D to Z. A "D" diamond is absolutely colourless which is extremely rare . An "E" colour and "I" colour are colourless to near-colourless. As the letters go through the alphabet, the yellow tint is more defined.