From "A World History Encyclopedia" (sources not given):
Quote:In the past coins were actually made of gold, silver or other metals. Their value depended on the amount of gold or silver they contained. Some people would make counterfeit coins by mixing gold or silver with a cheaper metal. However you could check if a coin was genuine by dropping it. If it was made of the proper metal it would 'ring true' of have the 'ring of truth'.
From the Online Etymology Dictionary (first usage cited as 1850):
Quote:Meaning "resonance of coin or glass as a test of genuineness" is from 1850, with transferred use (ring of truth, etc.).
From The Free Dictionary:
Quote:ring true
Fig. to sound or seem true or likely. (From testing the quality of metal or glass by striking it and evaluating the sound made.)
From "Phrases-dot-org-dot-U:"
Quote:"Due to poor equipment and the scarcity of precious metals, metal workers of the Middle Ages were not able to produce coins that were uniform in appearance and weight. This situation gave criminals an opportunity they couldn't resist. Thus, when in doubt over a coin's validity, a tradesman would drop it on a stone slab to "sound it." If phony, it'd make a shrill or dull, flat tone in contrast to the clear ring of a true coin. By extension, a story tested and found acceptable is said to ring true, and its opposite, to ring false or hollow."
-Nancy M. Kendall, "True and false", "Christian Science Monitor" 3/19/2003
Ms. Kendall cites 'The Encyclopedia of Word and Phrase Origins,' by Robert Hendrickson; 'The Morris Dictionary of Word and Phrase Origins,' by W. and M. Morris; 'The Barnhart Dictionary of Etymology,' by R. Barnhart in her sources.
Although i found several references to glass ringing true (such a method is used to distinguish crystal from glass), the overwhelming opinion (although not by much) seems to favor coins. The ring of a bell finished a distant third.