aramis erak
Legend
Tehee.. but in some worlds it is fun to see what gold you have from which country. Assome enemy country would not want you to pay with any given currency.
If history is any guide, they'll accept it based upon public trust in its relative purity. Coinage as other than mark of who certified its purity really only begins to take hold in the 1600's, and doesn't become the standard until the 1800's...
French Livre 1 coins were about the same weight as English £1 coins... but at various points, trust in the french king's coin was higher than the English, and vice versa. Whichever one was debasing less was worth more in both... per unit weight.
(Note that the debasing with copper is why the roughly 14kt coingeld 1dwt coin was worth about 1 shilling... the "pure" 20 kt (which isn't 100% - that would be 24 kt - but was about as pure as it got in the day) was worth about 12 pence instead of the 20 that a dwt of pure/pure-ish gold would be. Debase it to 10 kt, and it's worth about 10 d.
In other words, the coin simply "assures" weight and purity, based upon the public trust in the minter. But that's an inconvenient thing in most fntasy campaigns.