A piece of stone, colored glass, or tile used with others to make mosaic patterns on floors, walls, ceilings, etc. The pieces were set in cement by Roman and later craftsmen. Small cubes of up to 1 inch in size were used to make the floors. In the Roman period, tesserae, sometimes inscribed, were in circulation for various purposes. These were small tokens of bronze, lead, terra-cotta, and bone. The earliest tesserae, which by 200 BC had replaced natural pebbles in Hellenistic mosaics, were cut from marble and limestone. Stone tesserae dominated mosaics into Roman times, but between the 3rd-1st centuries BC tesserae of smalto (colored glass) also began to be produced. An important variety of glass tesserae, appearing first in Roman mosaics of the 4th century AD, were those made with gold and silver leaf.