Ducat (coin)

The ducat /ˈdʌkət/ was a gold or silver coin used as a trade coin in Europe from the later medieval centuries until as late as the 20th century. Many types of ducats had various metallic content and purchasing power throughout the period. The gold ducat of Venice gained wide international acceptance, like the medieval Byzantine hyperpyron and the Florentine florin, or the modern British pound sterling and the United States dollar.

The word ducat is from Medieval Latin ducatus = "relating to a duke (or dukedom)", and initially meant "duke's coin" or a "duchy's coin".

The first issue of this type of coin is thought to have been under king Roger II of Sicily, who was also the Duke of Apulia and who, in 1140, coined ducats bearing the figure of Christ and the inscription, Sit tibi, Christe, datus, quem tu regis iste ducatus meaning "O Christ, let this duchy, which you rule, be dedicated to you."

Doge Enrico Dandolo of Venice, whose title means duke, introduced a silver ducat whose types are related to the ducats of Roger II. Later gold ducats of Venice, however, became so important that the name ducat was associated exclusively with them and the silver coins came to be called grossi.

The Venetian business model of the 13th century was importing goods from the East and selling them at a profit north of the Alps. They paid for these goods with Byzantine gold coins but when the Byzantine emperor Michael VIII Palaiologos backed a rebellion called the Sicilian Vespers in 1282, he debased the hyperpyron. This was just one more in a series of debasements of the hyperpyron and the Great Council of Venice responded with its own coin of pure gold in 1284.

...
Wikipedia