pietra dura (visual works) en

Inlaid works in which pieces of hard, polished stone have been set into marble or another hard surface; a Florentine specialty often used for decorative table tops and small wall panels. The singular form, "pietra dura," is used within Italy to refer to works incorporating a single type of stone; but outside Italy it refers to works using combinations of stones. Pietra dura works were carved in classical Rome, and the techniques for cutting such hard stones were revived in 16th-century Florence, where a workshop established under the patronage of Grand Duke Cosimo I de' Medici produced decorative panels; the workshop was refounded in 1588 as the Opificio delle Pietre Dure. The hardstones used are semi-precious stones, typically agate, chalcedony, jasper and lapis lazuli, but do not include marble or precious stones. Stones of the requisite hardness for such work generally fall between 6 and 10 on Mohs' scale of hardness, i.e. between orthoclase and diamond (lapis lazuli being the notable exception).