Every pietre dure
mosaic produced at the Galleria dei Lavori in Florence or at another manufactory was based on a full-scale design commissioned from an artist. Beginning in the sixteenth century these models were either finished paintings in oil on canvas or, more often, watercolors on paper. When choosing his colors, the artist had to consider the natural palette of the available stones and set forth general, rather than precise, chromatic instructions. The precious material was entrusted to only the most skillful masters, who executed the pietre dure
work, often changing small details that were dictated by the patterns in the hardstone itself. The pieces of stone were cut using an archetto—
a chestnut bow saw—with dampened abrasive powders spread on its iron wire.
Large vessels or cups were produced at the grinding mill. The grindstone wheels were often driven by waterpower or pure physical effort. In many cases it could take a group of specialized lapidary workers years to finish one object. It is remarkable that the technical aspects of the art of cutting hardstones had changed little since ancient times. Even today, traditional methods have to be used to create a pietre dure masterpiece.