Spesmilo

The spesmilo is an obsolete decimal international currency, proposed in 1907 by René de Saussure and used before World War I by a few British and Swiss banks, primarily the Ĉekbanko Esperantista.
The spesmilo was equivalent to one thousand spesoj, and worth of pure gold, which at the time was about one-half United States dollar, two shillings in Britain, one Russian ruble, or Swiss francs.
The basic unit, the speso, was purposely made very small to avoid fractions.

Sign

The spesmilo sign, called spesmilsigno in Esperanto, is a monogram of a cursive capital "S", from whose tail emerges an "m". The currency sign is often typeset as the separate letters Sm.
In Unicode, the character is assigned in version 5.2.

Miscellaneous

The stelo was another currency unit used by the from 1942 to the 1990s.
An Esperanto version of the board game Monopoly uses play money in denominations of spesmiloj.