Commerce in the Dodekapolis rides a powerful current, one that is not easily routed, and one that has a tendency to carry all along with it. Whether it flows quickly or slowly, it has a momentum to it that even Gods and Arches are subject to. Such is the sheer volume of goods, services, and coin that weave their way through the multiverse. There’s really no mystery to it, despite what some may try to tell you. The fact is, with the quadrillions of planar denizens, large or small, there’s just too much inertia behind the planar economy for even the wealthiest to meaningfully influence. This volume pulls down peaks and fills in valleys. At least, this was true until the Paroxysm a few years ago… like many formerly stable systems, the market has seen a fair bit of uncertainty recently.
Currency among the planes is anything but standardized, but the Dodekapolis is a different story. There are three major currencies among these hubs of trade: coins, diamonds, and notes.
Coins of the Dodekapolis are dodecagonal, an inch across, one twelfth of an inch thick with a ridged edge, and weigh a quarter of an ounce. Mostly copper by a slim margin, they are an alloy of several metals and alchemically colored appropriately. Depending on the time of minting and the city they were minted in, they may display any number of designs on their faces. The four cities that mint coins are The City of Brass, Dis, Gewirgrau, and Voilauringocyfnos, though Vos Inaril has been fighting a political battle for thousands of years for the privilege. A few hundred years ago they were granted a concession allowing the minting of iron coins, but this is mostly seen as an insult.
A copper coin is common pocket change and one can buy you a pint of cheap brew, street food, or public transit around a city. Common tipping money.
A silver coin is worth ten copper and is the biggest coin an average person might be expected to carry. Most working class people in the dodekapolis make about three silver a day, and living expenses generally leave them with one of those left. It’s the typical price for private transportation within a city.
A gold coin is worth a hundred copper and is the pocket money of the upper class or of those who like to show off. Mercenaries typically make one gold a day while guild wizards, barristers, and high-ranking bureaucrats make about three gold a day.
A platinum coin is worth a thousand copper and is often a novelty piece as it is so rarely used to conduct transactions in open marketplaces. The only people to carry these are ultra-wealthy nobility and celebrities. A platinum coin can pay well over most people’s monthly rent/mortgage.
Iron coins are rarely used in the Dodekapolis, mostly relegated to “backwater” (not in the Dodekapolis) settlements where things are cheaper. They are worth one twelfth a copper, and many businesses in “proper cities” do not accept them.
It can be helpful to have a comparison to real-life amounts of money to get an intuitive grasp of what these coins are worth and how you can come up with prices on the fly. A copper piece is worth about three USD, making a silver thirty, a gold piece three hundred, a platinum piece three thousand dollars, and an iron piece twenty-five cents.
Diamonds are frequently used as an anonymous option over coinage, which can be tracked via various mint marks or other yet unknown methods, and are popular among not just criminals but anyone concerned about privacy. This is due to the fact that diamonds can simply be held to a certain unifying standard. This could of course also be done with precious metals, but no one wants to carry gold bars in their pockets.
Diamonds used this way must be flawless, round, perfectly cut, and exactly one grain in weight (just shy of one third of a carat). Deviations from this weight and quality standard are not haggled around or prorated. It is usually easy enough to find a gemcutter who can provide diamonds to this exacting standard specifically for use as currency, but who can/should be trusted is a matter of much hot discussion. Getting such a gem’s validity confirmed usually costs ten copper.
Used as currency, such diamonds are generally accepted to be worth three gold, three silver, and three copper. Gems in general not used as standardized currency in this way vary greatly in cost.
Scrolls are a currency that are most often in the form of a cloth contract rolled onto a spool with ink writing, ribbons, wax seals, and at least one blood thumbprint. They act as a one-time key to a lockbox or bank vault (using one to open its target destroys it so a new one must be made) and can have any conceivable value though it is unheard of for one to start with a value of less than several thousand copper. They are always heavily warded with magical protection and self-identification of at least Power 12, though the exact nature depends on the issuing authority.
Scrolls can usually be freely traded as their value is generally not tied to a specific person, but whoever possesses it. Common best practice is to check with the issuing authority (usually a noble, bank, or guild) before accepting a scroll as payment.