Eye color is considered a subset of coloring, and coat color definitions often include standards for the eyes, as many genes which control eye color will also affect the coat color or "vice versa". The American Fancy Rat and Mouse Association (AFRMA) lists black, pink, ruby, and odd-eyed (two differently-colored eyes) as possible eye colors, depending on the variety of rat shown. "Ruby" refers to eyes which at a glance appear black, but which are on closer observation a deep, dark red.