Provide a legal tender for private and public debts

Ensure the bank has always has enough money to cover total deposits

Act as a universal equivalent for all commodities

Transfer purchasing power from the present to the future

They were only used as a unit of account, never for current payments. 

They were carved from gold, making them inherently valuable.

they were easily divisible into smaller pebbles for small transactions.

Their value was transferred through social recognition and record-keeping without the need of physical transport.

Commodity quotation

Unit of account 

Medium of exchange

Physical security

The massive spike in the US monetary base during the 2008 financial crisis

The transition from the gold standard to fiat currency under Franklin Roosevelt.

The introduction of the Bretton Woods system in 1944.

The 1932 transfer of gold from the Fed of New York to the Bank of France via the "earmarking"

The purchasing power remained valid based on the community's unquestioned belief in its existence and value.

The stone was eventually recovered and placed in the central bank.

The German government issued paper certificates representing the sunken stone.