The highest valued currency unit is the currency in which a single unit buys the highest number of any given other currency or the smallest amount of a given good.
Mostly the calculation will be done by referring to units of United States dollars (USD).
By way of comparison, the highest valued currency unit is the Kuwaiti dinar, valued at US$3.39248 as of January 3, 2005, with the Maltan Lira coming in a close second at US$3.11006.
The self-proclaimed Principality of Seborga issues a currency known as the Luigino pegged at exactly US$6.00
See also
Least valued currency unit