5 Ducats - Frederick William

Frederick William, the "Great Elector," issued multiple-ducat pieces during the 1660s partly as diplomatic currency — high-value gold coins presented as gifts to foreign courts and military officers whose loyalty was worth purchasing. Brandenburg-Prussia was then consolidating its position after the Thirty Years' War had left the region fragmented and largely bankrupt, and conspicuous gold coinage functioned as a political instrument as much as money.

The .986 fineness places this at the extreme upper end of contemporary gold standards, a deliberate signal of fiscal credibility from a state that had only recently built a functioning treasury.