Currency
There are five ranks of currency: Copper, Silver, Gold, Obsidian and Platinium. These materials are rare and thus used for coins due to their value. One of each is usually simply referred to by the material name, which means one copper coin is referred to as a copper, one silver coin is referred to as a silver and so on. Multiple is referred to as [amount] Coppers, Silvers, Golds and so on. The exception to that are Platinium coins, they are called one Plat and [amount] Plats.
There are also pieces worth more than one coin. A square with rounded edges is worth ten, a rectangle with rounded edges is worth fifty, a triangle with rounded edges is worth a hundred, a large coin with four square holes in the middle are worth fife hundred and in the case of Platinium there are also small pyramids which are worth one thousand plats, which is enough to buy a city.
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The conversion is simple, one thousand of one equals one of the next highest material.
1.000 Coppers = 1 Silver
1.000 Silvers = 1 Gold
1.000 Golds = 1 Obsidian
1.000 Obsidians = 1 Plat
There used to be a type of coin above platinium made of aldirium, a material discovered by Aldir Velcome. A decade after its discovery it was also discovered that it can destroy external and internal mana and became the basis for what is now called anti-magic since it is loaded with anti-mana particles. That's why coins still made from aldirium are some of the rarest collectables since most of them were confiscated by the church, exchanged for other coins and the molten down to make anti-magic gear. Only a few collectors can say that they have even a single aldirium coin.