Traditional name for the marbleworkers of Rome (marmorarii Romani) active in the 12th and 13th centuries. Their characteristic use of polychrome marble and mosaic inlay is also known as cosmatesque art. The description of the marbleworkers as 'Cosmati' was based on the incorrect assumption that all Roman decorative marblework in the Middle Ages was produced by one family of artists of that name. It was only as a result of research that it became quite clear that there were many artists and families of artists involved, with the Cosmatus family that gave its name to the style being among the latest, active in the second half of the 13th century. The names of more than 50 artists are so far known, most of them belonging to seven large family workshops, with documentary evidence of members from several generations in each family.
The Cosmatus (Cosma) was a Roman family, seven members of which, for four generations, were skilful architects, sculptors and workers in decorative geometric mosaic, mostly for church floors. Deodato and Giovanni belonged to the last generation.