Small Copper Coin:
The smallest form of currency in Tilia, a single one of these coins can't buy you much more than a cup of water.
Large Copper Coin:
Equivalent to 5 small copper coins, one of these coins can buy you a loaf of cheap bread.
Silver Coin:
Worth an amount equal to 5 large copper coins, just a single one of these can buy you a night at a local inn, or a full meal at an average restaurant. This is also where you'll start to be able to purchase simple weapons like a dagger for just a coin or two.
Electrum Coin:
Composed of an alloy of 90% silver and 10% gold, it's worth 5 silver coins, and is a very popular coin with merchants. One electrum coin can buy you a full set of leather armor, or a half decent sword.
Gold Coin:
Worth 5 electrum coins, it's the largest denomination of currency you'll see most people carry around. For just 1 gold coin you can hire a D rank adventurer for week, and with 10 of them, buy yourself a light horse for travel.
Platinum Coin:
Worth 100 gold coins, it's only really used in large scale business. Most people will never hold one of these in their lives. With just a singular platinum coin, you can hire A rank adventurers for a week, or alternatively buy yourself a set of high quality steel plate armor, a kite shield, and a longsword with 20 gold coins worth of value to spare.