Pigmentation or skin darkening results from the accumulation of a dark pigment called melanin in the outer layers of the epidermis. UV rays initiate the synthesis of melanin in the epidermal melanocytes by a complex oxidation mechanism involving inflammatory messenges, free radicals, and different enzymes. The melanin produced in the basal layers of the epidermis is then transferred by to the upper surface of the epidermis following the 28 days cycle.