There's a silver standard. Most day-to-day payments are in copper if very small, in silver if larger. Gold coins exist but most people have never seen one. The general word for 'money' is vensin, literally 'silver pieces'. It's usual to bury a silver (or even gold) coin under the doorstep when a new house is built "so there's always money in the house". The coin doesn't have to be valid, it can be obsolete or foreign, as long as it is of precious metal. Digging it up is said to bring bad luck and poverty.
I use the English equivalents 'penny' and 'shilling' for the common copper and silver pieces, the literal translations 'rider' and 'crown' for the larger denominations (bornan and valsen). Large sums are usually calculated in (silver) riders.
The smallest coin is the (copper) halfpenny, sometimes literally a penny cut in half, more often a thin thumbnail-sized copper coin. A halfpenny will buy you a small bread roll or half a pint of weak ale. A penny is slightly larger, about half an inch in diameter.
Fourpence is enough to have a letter read to you by a luchan so galan. A fourpenny piece, half a shilling (tavensen ile) is usually silver, though it can be copper.
The shilling (tavensen, 'little silver piece'), worth eight pence, is the most widely used coin for slightly larger payments. A skilled housemaid earns about eight shillings a week and her board. A clerk will write a letter, or a bath-attendant wash your body and hair, for one or two shillings. A night in an inn with a simple breakfast can be got for two or three shillings.
Each town mints its own shillings. They typically have the town crest or device on one side and something arbitrary changing every few years on the other, usually including the words 'one shilling' and the name of the town. Some towns have two-, five- and/or ten-shilling pieces.
A rider is worth 20 shillings. Riders are struck by the mint-masters in Valdis and Ildis. The 'heads' side has the king's or queen's head and the words "[name], Valdyis valan" ("[name], king/queen of Valdyas") on it, the 'tails' side a horseman (hence the name 'rider'). They're quite large, about an inch and a half in diameter, and almost thin enough to roll up.
Most large payments are in riders. A well-schooled scribe can earn 1 to 3 riders a week.
Crowns (valsin, also used meaning 'big money') are gold coins about half an inch in diameter, worth 20 riders, with a crown on the reverse side and still the king's or queen's head on the 'heads' side; they're very rare. Even more rare are 'eagles' (orla) and 'double eagles' (iyorla) with one or two eagles on the tails side, worth 6 and 12 crowns respectively.