The symbol commonly found on Spanish doubloons is 2S. Spanish doubloons are commonly associated with pirate treasure. The 2S stamped on a gold doubloon denotes the denomination and value of the coin.
Spanish doubloons were used until the mid-19th century when Queen Isabella II replaced the currency with the Spanish reales. Gold doubloons weigh 6.77 grams and were primarily used by wealthy members of Spanish society. The coins were also minted in silver, which were the most commonly circulated doubloons. Gold doubloons have clearer images and engravings than silver, because they were circulated less. This makes these coins more desirable to collectors. Not all doubloons were minted in Spain; Portugal and the Spanish colonies of Peru, Nueva Grenada and Mexico continued to mint the coins, even after gaining their independence.