I don't really have much to add directly to the topic in question, but I will point out that Portuguese johannas do seem to have circulated in the colonial worlds, long after their issue date.
In 1801, the governor of the Australian colony of New South Wales issued a list of legal tender foreign coins, along with their legal tender values. The Portuguese johanna and half-johanna were top of the list. Their legal tender values were set at exactly £4 and £2, respectively.
The whole point of this list was to assign inflated legal tender values to the foreign coins then circulating in the colony, in an effort to dissuade merchant ships from leaving the country with all the coins - which was a major concern for a colony that was less than 20 years old and still imported everything and exported nothing. In Britain, the johanna was tariffed at £3/12/- or in other words, the johanna was worth eight whole shillings more in Sydney than it was in London.
In the pre-Revolutionary American colonies, each colony set it's own exchange rates for johannas, which also seem to have been typically in the £4/-/- to £4/10/- range. The colonies also had "regulators" - jewellers and goldsmiths who would weigh the circulating foreign gold coins, drill and plug extra gold into them if they were found to be slightly lightweight, then stamp their own jeweller's mark onto the verified coins. These "regulated gold coins" are of course highly sought after by American collectors, though Portuguese collectors might frown upon them as merely "damaged coins". Obviously, anything found to be either fake or seriously underweight would simply be rejected by the regulators. Equally obviously, a regulator's stamp wouldn't have been that difficult for a counterfeiter to replicate.
With the passage of the Constitution in 1789, the Federal government gave itself the role of regulating foreign coin (Article 1, section 8, clause 5). In
1793, an Act was passed doing just this, setting "the gold coins of Great Britain and Portugal" legal tender at 1 dollar per 27 grains of gold; that gave the johanna a legal tender face value of US$16. This rate was confirmed by the
Act of 1806 and as far as I can tell remained in place until foreign coins were officially withdrawn in 1857.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis
Posted 07/01/2026 6:29 pm
