The Gold Ducat is a signature format used by the Czech Mint to issue commemorative "rounds" which are not legal tender. Its size is slightly larger than one tenth of a troy ounce. The coin follows the format of the first Czech ducat coinage, introduced at the beginning of the reign of King Charles IV, Holy Roman Emperor (in 1346). Because of their high fineness (23 1/2 carat) and stable weight (3.5 g) ducats soon became a basic gold nominal tender in most European countries. However, for lack of local raw material, the Czech ducat was not as widespread as for example the Hungarian ducat.
There are also multiples, e.g. two ducats, five ducats or ten ducats. The Mint also issues Silver Thalers.