The Archipelago operates on a common system of currency throughout Aradia, Eyr, and formally Mystara. While trading and bartering is highly preferred, passing coin is a secondary practice. Most people on the western coast of Eyr prefer exchanging goods, for they can be utilized to suit immediate needs.
Coins of the archipelago are copper, bronze, silver, gold, and the exceptionally rare platinum coin. In the past, coin was minted by the reigning monarch in their own likeness and regulated under that leader accordingly. Today, coins are created by a mint of unknown location and ownership. There are no details as to who mints the coins nor by the way it is done. It is however widely accepted that the flow of coin is regulated in such a fashion that the value is universal among the remaining islands of Eyr and Aradia.
The downward and upward conversion of coins, turning ten farthings into a griffon for example, can be done by most businesses or whoever happens to have coin on hand. Farthings are sometimes converted down by splitting them, using a chisel and a mallet to make a half-farthing. This is a common practice relegated by the poorest of traders.
When figuring out your character's net worth, (the total amount of liquid currency assets upon their person or stashed away,) consider what type of coins may be on hand. Note that pulling out a bag of gold would be showy, if not a distasteful boast of wealth. Exercise caution when throwing around money, for it may place a target upon one's head!
The average person would likely carry the cash equivalent of $/€1 - $/€ 100 in coinage. The majority of coins one would have on hand would be a mix of copper, bronze, and occasionally silver. Gold is typically exchanged between businesses. Platinum is an extremely rare coin to see and is most often found within the vaults of nations and covetous dragons.
Real life dollar/euro amounts have been appropriated for coins to help players understand their value. Copper coin, called farthings, are worth about a $/€1 and will buy a weak drink at a tavern. Bronze coin, called griffons, has a value of about $/€10 and will buy a small load of groceries from the general store. Silver coin, also known as schillings, are worth about $/€100 and can buy a bulk of goods like weapons, fine clothing, and furs. Gold coin, called florins, are worth $/€1000 and can buy luxurious goods and top quality gear or pay rent on a large estate for a month. Platinum coin, known as platts, have the value of $/€10,000 and is generally in the hands of nations to buy equipment for their armies, build naval fleets, and erect strongholds.