Another, more realistic way is to list products in larger quantities. If prices are constantly changing, it is probably more like wholesale exchange anyways. So instead of barrel of grain costing 2.37 gold coins, list the price as 237 gold coins for 100 barrels. You can also add some extra charge for buying less than listed quantity, for example rounding up to nearest full gold coin.Yes... it would work.
Hisorical notes: platinum was cheaper than gold (actually, they used platinium as fake gold since it weight similar), only around XX century they found larger deposits of gold and the price changed. Another funny fact, in Poland the parliament made an edict that peasants are not allowed to wear gold jewelery Althrough, I think it was a very rare "problem" that applied to Poland of that period only
I too don't see a problem with introducing the whole copper -> silver -> gold paradigm. I wouldn't add in platinum pieces though (like Everquest does), that doesn't make any sense historically as far as I know.
Furthermore, recognize that a gold coin was extremely valuable in the eyes of non nobles. From what I understand, many peasants may have never owned one.
No... I need 1/100 of something, half or quarter would not solve anything since I could just make all prices x4 and avoid it. I need much lower denominations.
Why not do what they did in medieval England and have half pennies and quarter pennies? They used to cut pennies into halves and quarters and use those for small value transactions.
Well, I can't make coins weight for that game, you don't also lose money by being robbed. I simply don't need the second coin type in that game for any reason except for the small wares trade (any probably mood).
Lastly, just because you've got 2 or 3 types of coins to keep track of doesn't mean things have to be complicated. You could automatically consolidate coin types when making transactions or looting money, for example. Under the hood you could just keep track of how many pieces of copper (or half pieces) a player had, and do all transactions from that pool. Just display the calculated amounts of copper, silver and gold on their character sheets and for merchant prices.
Doing something like the way Everquest used to would introduce more realism, but might not appeal to everyone. In old EQ, coins did not consolidate and they had weight associated with them. Carrying around your entire fortune would weigh you down and made travel risky if you got killed and couldn't get back to your body. Thus people would actually go to the bank to have their coins exchanged for more valuable types, or to store them for safe transfer. Selling at merchants would still automatically consolidate coins though.
OK, maybe let's ask about it from another side since many people mentioned it. Assuming there is no need for the second coin type at all (there are no these small wares), would you, as a player, still want it for the immersion purpose (the game is advertised the way it indicates increased level or realism/immersion)?