Silver Standards

The 1889 Havana treaty confirmed the standardisation of an international currency to encourage trade between the major powers. Signatories of the initial treaty included the empires of Spain, Britain  and  Germany, and the United States  and Confederacy.
The success of the silver standard as it became know  encouraged other countries to join, until almost the entire world was using the standard.
In many places this has now replaced local currency, you can go into a gentleman's outfitters in Truro and spend Standards or Sterling.