Agio
Agio (Italian aggio) is a term used in commerce for exchange rate, discount or premium.
The variations from fixed par values or rates of exchange in the currencies of different countries. For example, in most countries that used the gold standard, the standard coin was kept up to a uniform point of fineness. In particular, a freshly minted English sovereign was in a fixed relation to freshly minted coins of other countries: 1 ₤ = 25.221 francs = 20.429 marks = US$4.867, etc.