Monetization is the process of converting or establishing something into legal tender. It usually refers to the coining of currency or the printing of banknotes by central banks. Things such as gold, diamonds and emeralds generally do have intrinsic value based on their rarity or quality and thus provide a premium not associated with fiat currency unless that currency is "promissory". That is, the currency promises to deliver a given amount of a recognized commodity of a universally (globally) agreed-to rarity and value, providing the currency with the foundation of legitimacy or value. Though rarely the case with paper currency, even intrinsically relatively worthless items or commodities can be made into money, so long as they are difficult to make or acquire.The term "monetization" may also be used informally to refer to exchanging possessions for cash or cash equivalents, including selling a security interest, charging fees for something that used to be free, or attempting to make money on goods or services that were previously unprofitable or had been considered to have the potential to earn profits.Still another meaning of "monetization" denotes the process by which the U.S. Treasury accounts for the face value of outstanding coinage. This procedure can extend even to one-of-a-kind situations such as when the Treasury Department sold an extremely rare 1933 Double Eagle, the amount of $20 was added to the final sale price, reflecting the fact that the coin was considered to be issued into circulation as a result of the transaction.