(Also see Honed and Tumbled Stone, Polished Stone and Pebble Tile and River-Rock Mosaics)
Natural stone is a product of nature and includes granite, marble, travertine, slate, limestone, onyx, pebble tile and river rock. Polished stone will have a slick, shiny and reflective surface. Honed and tumbled stone will have a matte, dull finish and may also contain deep voids and pitted areas. All stone should be pre-sealed before grouting to prevent grout pigment from permanently staining the surface of the stone.