Skin and coat in cats can sometimes change color, become darker or lighter. This can be both a normal process and a sign of serious illness. If skin or wool have any color, except white, say about pigmentation.
Color can be brown, black, red, yellow and violet-blue. If the skin is darker than usual – then there is hyperpigmentation. Their coat changes over time, not dramatically, but such processes are observed.
Color wool can become more dark, bright, becomes dimmer, brighter. All this is considered normal but if changes are striking, the kind of animal has changed for the worse, should think.