Tostão - João VI

The tostão denomination had been largely absent from Portuguese silver coinage for decades before João VI reauthorized it following his accession. João spent much of this issue's production years ruling from Rio de Janeiro, having relocated the entire Portuguese court to Brazil in 1807 ahead of Napoleon's invasion — an arrangement that lasted until 1821, meaning these coins were authorized by a king governing a European nation from another continent.

The .917 fineness is notably high for subsidiary silver of this period, when most European mints were quietly debasing comparable denominations.