In ye olde Dragon Warriors, Coin was Copper, Silver and Gold.. but in Dungeon World we have
A Multitude of Coinage
Each kingdom tend to make their own coinage, and the exchange rate is not common knowledge, for reasons (below). Common folk, within the kingdom are barely going to understand their coinage going up or down outside their own town, let alone country, if it costs a silver florin for a barrel of wine today, it'll cost a silver for a barrel next year, and anyone trying to tell you otherwise is a cheat, and a liar, and will be run out of town.
Since almost any town will have some kind of 'barrel' of 'alcohol' which will invariably costs 1 silver, there will always be some kind of pushback on inflation. Also, because the god of inflation has been imprisoned by several very powerful heroes who want prices to stay the same.
So, Coinage never has to worry about being devalued, prices will, with fluctuations from supply and demand, always hover around the same value. and lifestyles as well.
Copper is for the poor, people who need to trade in copper are considered lower class, and the lower class love it, because they always managed to get the better end of a deal when some middle class pays for things with silver, and no change.
Silver is the trademans and merchants main coin, they will happily deal with all varied forms of coinage, and with the help of a street mage, always ensured that they don't get ripped off.
Gold is the coin of Kings.. and Nobles, and Gentry and people who want to be Nobles and or Gentry, and Heroes.. because Heroes somehow seem to be finding so much of the stuff.
But, Like many things in life, its not so easy to be carrying around all this coinage.
In The old Dragon Warriors, with a 10:1 ratio on things, and 10 coins to enough to carry let alone 100, Buying a peasants house at 10 gold, is only 1000 x the cheapest coin, so 1000 hours labour = a house? right?
Well, Then along came realism.. Dungeon World started looking at the metals in circulation and determined that Pewter, at least medieval, magical world Pewter, was slightly more expensive to make than silver (which bends and can technically be magic'd away) has magic resistant properties, To the point where a coin of pewter is worth 10 silver, and a gold is worth 10 pewter. Interestingly, Pewter contains lead, and is constantly poisoning people, but with an abundance of magical healing, its not noticed like we know of on Earth.
Then too, the common class decided that since wood is a worthy substance by itself, and people of certain class want a kind of recognition, certain woods, stained and sealed in a resin like substance, would count as a kind of thieves world coinage. Not as simple to make as just melting down some copper, but still plentiful enough, its has an almost 15:1 ration to copper.
Well of course, its a little easier to carry half a coin, than 5 other coins, and don't clink so much in the wallet, so snipped coins started to make circulation, til the powers that be decided that we can't have snipped chunks of metal where its unsure if its 45% or 55%. So the Moons started to make an appearance, and you can get gold, pewter, silver and copper moons in many states.
Then later, magical fused coinage, Gelds were discovered in magic councils, considered as worth much more to a mage than anyone else, they are often stamped differently by the magi, but not required. A geld might be accidentally traded by non magi for their metal worth, and the lucky mage will pick one up at the metal price, but its usually considered to be 20x the worth of the coin to a magi, and as such as become a worthy coin for the wealthy.
Note: Copper and Silver Gelds can cope with only 1 magic point, as they tend to melt with more infused, and as such are closer to 10x worth for a mage, but while Gold can normally cope with 3 magic points, Gold has been known when fused with some metals to cope with as much as 7 magic points.
Rarer is the Octiron Coin, rumoured to be created when 8 magic points are infused into a gold coin using a crystal rod, The Octiron coin is somewhere in the range of 1000x gold crowns.
We have not touched on the chunkier and heavier Dwarven varieties, which are typically twice the size and three times the worth, as they resist any tampering, and the artistic elven varieties which are only worth more for their beauty, as a coinage, they lose worth as soon as human hands mar and tarnish their faces, and return to bland versions within a few days of common usage. though, still worth 1.5 times normal worth to a clever eye.
Many 'lesser' races still trade goods, but use human coinage if its available, yet, pewter and silver tend to be pooled together.
In the Demon realms, trapped souls exist in a crystal like structure when touched, but in a softer form when not, are both used as a currency and a consumable, and when brought to the surface are traded in back alleys and black markets.
Pretty much, once anything is common enough, it becomes a kind of currency, as such the apothecary world trades internally with empty vials as they can cost somewhere between a pewter and a gold to manufacture, and are only really used by apothecaries and heroes.
So what of these exchanges? well, the kings of the world, have for the most part discovered one thing to keep their countries in flow. exchanging currency between traders and Adventurers can be, in itself, profitable enough to maintain the border guards, passes, diplomats and trade relations, instead of war. War is costly, the benefit is limited, but currency exchange?
So when players get to the edge of the country, there might be a border guard who can 'change' their money.. its ALWAYS a rip off.. 10 Zonti for 9 Jebas? but on return, 10 Jebas for 9 Zonti? hang on?
but in town, no-one is going to.. legally.. exchange other coins.. except of course, for a fee.
