This is an excellent photograph of a black Sphynx cat. The patterns and colours of hairless cats follows what would have been in their fur if it existed. The hr gene causes hypotrichosis. The skin is not jet black. It is a ligher shade of black – more charcoal – than the coat would have been. The colour is created by the melanin creating cells in the epidermis which are called melanocytes. As I understand it the vestigial hair strand in the hair follicle is coloured by the melanin created by the melanocyte causing the cat to take on the colour of its missing fur coat.