The most commonly used currency (used in most parts of Telandron; Irigarn, Laydane and some parts of Kul), is called the Keshnik Conventional, named after the Earl who introduced it, a couple of hundred years ago.
The first piece is called the Gold Piece. It is roughly circular and is about half a centimetre thick,although these dimentions vary greatly depending on where and when it was minted. In the Kaylonic Empire Gold Pieces are minted with an Eagle on one side, the symbol of the Empire, and the head of the current ArchYandrite on the other. Alternatives are popular, such as having the head and twelve pillars.
In Kul a similar system is used, but the head is of the current monarch, and the other side is the symbol of Nagharos, the Scythe. In Laydane, a fish is used instead of the Eagle, in the Northlands it becomes an axe and the King, and in Thal Kol a fist and the monarch.
Generally when writing it is shortened to gp, as in "15 gp." In speaking it is either "Gold Pieces" or simply "Gold," as in "Fifteen Gold".
As as example, 5 gp would be enough to buy a dagger, a simple helmet or about 10 provisions or good meals. It would ensure lodging at an average inn for about a week.
The second coin is named the Silver Piece. It is roughly 3-4 millimetres thick and slightly wider in diameter than the Gold Piece. Again many differences are used in between the different nations, but the Kaylonic Silver is minted with the head of the ArchYandrite and the sigil of the Earl in whose kingdom it was minted.
Normally 10 silver pieces, or sp, or simply silver, as in "8 silver", make up 1 gold piece.
The final coin is the Copper Piece. Smaller again than the Silver Piece, it is obviously made of copper as the Silver Piece is made of silver. Ten copper pieces, or cp, or coppers make up 1 silver piece.
Generally you will find that gold is accepted anywhere, no matter whose face is stamped upon it. Gold is gold, after all. Unfortunately you will also find that many will pass off doctored coins which are mixed in with base metals, or with milled edges. The best thing is to try and get a feel of the proper weight and colour of the various coins, and you will not be deceived very often.