Decoration made by inserting one material within an incision, indent, or depression cut into another material to the same depth and finished flush. This may be accomplished using hard materials, such as black marble set in white, wood of one colour laid in wood of another colour (marquetry), one metal set in another, e.g. gold in steel (damascening), or brass set in polished tortoiseshell (boule or buhl work). Surfaces made up of very small pieces fitted together are properly mosaics because they are laid on and not in the background, although wood of various colours laid within a surface in Italian Renaissance designs does qualify as inlaid work and is called intarsia, intarstatura, or tarsia. Soft materials, such as paint, mastic, or coloured pastes, which harden after a while, really fall into the category of incised rather than inlaid work.