Porphyry is a purple colored stone with white speckles recognized for its high hardness. It has been used in sculpture and architecture since Antiquity, in particular in the manufacture of columns, pavements or colored draperies in sculpture, due to its color which was associated with imperial prestige. Over the following centuries, porphyry loses its imperial symbolism but retains its image as a rare and precious material and therefore has a purely decorative use.