When supply is difficult to increase, it is said to be hard money.
The Stock and the Flow and the ratio between these determine a money’s hardness.
- Stock: existing supply.
- Flow: extra production of supply in a given period
The higher the Stock:Flow ratio, the more likely a good is to maintain its value and stability over time.
Hardness of various forms of money is dictated by the technology of the time and society using the money. If seashells become easy to harvest because of a new type of net, their Salability across time will decrease. This is totally due to the environment of technology around the shells, and not the shells themselves.
Society will find the hardest money available to it - it doesn’t necessarily need it imposed on it by a government.