Important drawing by Gio Ponti of the Diamante line for Touring Carrozzeria Milan. A similar example pictured on page 167 of Gio Ponti: The Complete Work by Lisa Ponti. Ponti’s car designs where never realized, but his design ideas where very important for the development of the modern car. Provenance; the estate of Gio Ponti. A unique drawing by the most important Italian architect of the 20th century.