1763 Dutch Guilder, KM# 100.1
This coin is very close to a sterling silver florin, being .920 silver fineness and around the 10-11 g mark in weight.
It comes from a time when the Dutch Republic was a very heavy hitter in global trade.
They had extensive worldwide holdings – in both the East and West Indies and many of the stops in between. The Dutch merchant empire was also long lived, surviving largely intact until the Netherlands became allied to the French in the Napoleonic period; which resulted in the British moving in on unsupported bases of their enemies.
Before all that got going, coins like this one formed part of the currency of the British colonies, including Australia, probably from settlement since they rate a mention in Governor King’s Proclamation of November 19th, 1800.