The Opificio delle Pietre Dure, literally meaning Workshop of Semi-precious Stones, is a public institute of the Italian Ministry for Cultural Heritage based in Florence. It is a global leader in the field of art restoration and provides teaching as one of two Italian state conservation schools (the other being the Istituto Superiore per la Conservazione ed il Restauro). The institute maintains also a specialist library and archive of conservation and a museum displaying historic examples of Pietre Dure inlaid semi-precious stones artefacts. A scientific laboratory conducts research and diagnostics and provides a preventive conservation service.Being one of the famous artistic workshops of the Italian Renaissance, the Opificio was established in 1588 at the behest of Ferdinando I de' Medici to provide the elaborate, inlaid precious and semi-precious stoneworks. One of the masterpieces of the crafts is the overall decoration of the Cappella dei Principi (Chapel of Princes) in the Basilica di San Lorenzo di Firenze. The technique, which originated from Byzantine inlay work, was perfected by the Opificio masters and the artworks they produced became known as "opere di Commessi Mediceo" (commesso is the old name of the technique, similar to ancient mosaics) and later as "Commesso in Pietre Dure" (semi-precious stones mosaic).The artisans performed the exceptionally skilled and delicate task of inlaying thin veneers of semi-precious stones especially selected for their colour, opacity, brilliance and grain to create elaborate decorative and pictorial effects. Items of extraordinary refinement were created in this way, from furnishings to all manner of artworks. Today, artisans trained at the Opificio assist many of the world's museums in their restoration programmes.The Opificio workshops were originally located in the Casino Mediceo, then in the Uffizi and were finally moved to their present location in Via Alfani in 1796. After the end of the 19th Century the institute's activities moved away from the production of works of art and towards its restoration. At first specialising in hardstone carving, in which the workshops were a world authority, and then later expanding into other related fields (stone and marble sculptures, bronzes, ceramics).