I was always under the impression that D&D coins were more like modern coins, and are comprised of more than just the metal associated with them. I.E, a gold coin is not pure gold, but a mixture of metals and their value is set at what ever the governing body responsible for the minting says they are worth
Oh, goodness no! Modern governments were cutting down / getting rid of the precious metals in coins even before they started eliminating the Precious Metal Standards for backing said currency. What you're talking about with coins made of mundane metals with worth set by the government is Fiat Currency. With the exception of a few very long-lived empires, nobody could support Fiat Currency. Even then, it served the same purpose as it does now - to defraud poor people through currency devaluation. (Read the fight Americans got into over just adding Silver to the Gold Standard that helped inspire "The Wizard of Oz" sometime, it's crazy!) Rome could get away with it for a while during the high imperial period, but persons of substance just dealt in real gold, not nonsense like the Denarius, which went from 100% silver to 0% silver in the span of 200 years through debasement. As a result a 3rd century Roman Denarius was worth literally
nothing in Western Europe in the 7th Century when the Western Roman Empire had expired. Heck, it was probably worthless sooner than that just because Emperors decided to stop honoring the value of older issued currency in certain periods.
But the Solidus would remain the literal
gold standard of all of Europe for 1,000 years because its purity was maintained.
(if it was pure gold, everyone would just melt it down and sell the gold at it's weight!).
Yes. That the
whole point of precious metal currency. It's as pure as you can make it - hence
bullion rather than fiat money. That why merchants and money-changers have scales and why tampering with scales would cost you your hand or your head. Gold coins of a certain size weigh a certain amount and you can't fake it unless you gild lead. Mixing in other metals changes the density and any professional can easily identify the fraud. Trying to mix silver with other metals of similar weight noticeably discolors it too. If one kingdom tries to mint a diluted or shaved "Gold Piece" or some random bronze coin that says, "Good for 1/50 a lb of gold, trust me," it simply doesn't work. Everyone knows to treat them as lesser value than "real" gold pieces (or to refuse to accept them at all if it's fiat coin). Also, diluting Gold with Silver is how you get Electrum Pieces in the first place.
For simplicity sake, everyone just assumes a coin in one kingdom is the roughly the same value as the coin from another, regardless of the time they were minted in, so even gold coins found on the floor of a 1000 year old dungeon can be used to by a stay at the local inn.
The reality is exactly the opposite - the they have the same rough value because they have the same weight and the same substance, because it's
really weird to see people in a medieval setting dealing in fiat currency when it comes to portable treasure like Adventurers and merchants deal in. (Peasants can trade in beads or sea-shells locally for all the wider world cares - they weren't allowed to hold
real money or leave the manor anyway.)
Marty Lund