Pigments of colour are added to the hair early in the growth process. These pigments are made of a substance called melanin.
Melanin gives hair its natural coloured appearance.
The pigment granules in fully formed hair contain two key types of melanin:
Black/Brown (Ashen) has larger pigment.
The amount of Eumelanin determines the depth of the hair (How light or dark it is)
Red/Yellow (Warm) has smaller pigment. The amount of Pheomelanin in the hair determines the tone of the hair (the colour you see).