Scagliola
Scagliola is a composite substance made from selenite, glue and natural pigments, imitating marble and other hard stones. The material may be veined with colours and stuck on to a core, or patterns may be carved into a prepared scagliola matrix. The pattern is then then filled with the coloured, plaster-like composite. Then it is polished with flax oil for brightness, and wax for protection. The whole thing gives a  richness of colour not easy to get in natural marbles.