Blue monkey, Zanzibar Key Ring

Despite its name, the blue monkey is not noticeably blue: it has little hair on its face, and this does sometimes give a blue appearance. It is mainly olive or grey apart from the face (which is dark with a pale or yellowish patch on the forehead - the "diadem" from which the species derives its common name), the blackish cap, feet and front legs, and the mantle, which is brown, olive or grey depending on the subspecies.