Actually, "brunette", as it's name implies, is brown hair, making highlighting and shading easier. Black hair is usually referred to as "raven". Although Westerners can have black hair, it's more common to Asians, and brown hair, vice-versa. For black hair, a touch of blue could be added for highlighting; or a touch of brown.
ie; my wife is South-East Asian and her natural hair color is a VERY dark brown - black coloring is noticeably too dark for her. It depends on which ethnicity you want your figures to look.