1 Ducat - Frederick William I

Frederick William I loathed ceremonial expenditure and ran one of the most austerely managed treasuries in Europe, yet ducats were minted continuously throughout his reign — not for domestic commerce, but because gold ducats were the accepted currency of international trade and diplomatic payment, and Prussia could not conduct either without them. The irony of a king who famously wore a threadbare uniform producing coins in .986 fine gold was not lost on contemporaries.

The Frankfurt-standard ducat weight of 3.46g was a deliberate choice to ensure acceptance by Dutch and Hanseatic merchants without haggling over fineness.