Gold is a tender metal, difficult to find, dense and preservable. For these reasons, gold as money quickly spread from Asia Minor, when it has been used first, to the entire world.
Using this system requires to make some calculations: the touchstone allows to estimate the quantity of gold in an alloy, then to multiply for the weight of the piece of metal to find the quantity of precious metal contained. To simplify this process, it’s introduced the prefixed standard coinage, as the weight of the coins, such as, knowing the origin of the coin, the use of the touchstone was useless. Coins were coined with severely protected processes and then marked with symbols that guaranteed weight and value of the metal. Even if gold and silver were the most common metals for coins, other metals also were used. At the beginning of the XVII century, Sweden, for lack of precious metals, coined “piasters”, large copper plates of about 50 cm, with their value indicated. Their poor handiness has taken Sweden to issue first in Europe, banknotes in 1661.
The system of exchange goods has become a system of convertible money.
Paper values and not precious metal coins were under promise of a government or a bank to be changed in a certain quantity of precious metal, such as silver. From this it came the term ‘British Pound’, monetary unit guaranteed by a ‘Pound’ with silver for 92.5% , "Sterling Silver", then the value "Pound Sterling".
