Diamond colour actually refers to a diamond's lack of colour. Many diamonds exhibit certain hints of yellow, which acts like a filter and diminishes the spectrum of colours emitted. The colour of a diamond affects greatly on its value - the less colour in the diamond, the more valuable.
Wonderfully Diamonds only sells diamonds with a colour grade of D-J. Diamonds graded D-F colour are considered as Colourless, which are typically very rare and expensive; diamonds with G-J are considered as Near Colourless, with colours that are undetachable to the unaided eye but offer great value for money.