numismatics

numismatics \noo-miz-MAT-iks; -mis-; nyoo-\, noun:

the collection and study of money (and coins in particular).

If [the modern counterfeiter] is satisfied with a so-so product, perhaps hoping to pass it in a crowded fast-food restaurant or in a saloon's dim light, he can download images of genuine bills from the Internet, simply by getting access to the Web site of a numismatics club, then run off his own bills.
-- "Officials Wary of Wave of Computer Counterfeiters", New York Times, March 12, 1998

Numismatics...is, in the main, an auxiliary to the knowledge of the trade and mutual intercourse of the ancients.
-- J. Leitch

Numismatics ultimately derives from the Greek nomos, a custom or convention, which has the derivative nomisma, anything sanctioned by custom, especially the current State coin. It can also refer to the study and collection of medals.