The Pietra Dura technique involves use of a variety of natural stones and marbles that include agates, chalcedony, carnelian, lapis lazuli, onyx, malachite, mother of pearl, and others. Thin slices of these stones, which are cut with a small saw or copper wire and, are then were fitted closely together like a jig saw puzzle- usually into a bed of black marble - to form a decorative pattern. Black Belgian marble was commonly used to form the matt background into a variety of natural stones or various coloured glasses were intricately inlayed. Favourite Florentine subjects for Pietra Dura mosaics were flowers, leaves, birds and fruit.