The ducat 's a gold coin that was used as a trade currency throughout Europe before World War I. Its weight's 3.4909 grams of .986 gold, which's 0.1107 troy ounce, AGW, actual gold weight. History The first issue of this coin's thought to have been under Roger II of Sicily, who, in 1140, coined ducats bearing the figure of Christ, and the inscription, 'Sit tibi, Christe, datus, quem tu regis iste ducatus' (or roughly, "O Christ, let this duchy which you rule be dedicated to you." This seems to b… (More on Ducats)