Gray or grey is a coat color of horses characterize by progressive silvering of the colored hairs of the coat. Most gray horses have black skin and dark eyes; unlike many depigmentation genes, gray does not affect skin or eye color Their adult hair coat is white, dappled, or white intermingled with hairs of other colors. Gray horses may be born any base color, depending on other color genes present. White hairs begin to appear at or shortly after birth and become progressivly lighter as the horse ages. Graying can occur at different rates--very quickly on one horse and very slowly on another.