|This article is about an older version of DF.|
The game's currency is measured in "☼", called "dwarfbucks" or "db's" by some players. Each item has a specific trade value in ☼.
In order to activate the dwarven economy and sustain it, coins must be minted. The economy begins with the arrival of the Bookkeeper, who will arrive only after you have minted 2500 coins (5 stacks), and the Manager.
Coins are minted at a metalsmith's forge or a magma forge and can be minted from any metal other than pig iron. Coins made from copper, silver, gold, and platinum (and electrum, once the Dungeon master arrives) have special monetary value to the economy, while coins made from other metals are considered "commemorative coins" and serve only as trade goods whose value is 1/50th the material multiplier of the metal. Since you get 500 coins per bar of metal, this is equivalent to an item value of 10.
When the dungeon master arrives, all existing coins made of electrum and platinum will become legal tender - since it is possible to mint platinum coins before this happens, any dwarf who was fortunate enough to purchase them will become significantly more wealthy, to the tune of 15,000☼ per stack of coins.
Using coins as a trade good is not advisable as they have no quality levels. Allowing coinage in general circulation is not recommended as it aids nothing and dwarves tend to spend considerable time moving them around pointlessly.
Coins have little value in fortress mode and do not benefit the economy in any way, nor do they make anyone happier, but they do lead to massive slowdowns both in FPS terms and in terms of what your dwarves can accomplish. However, since certain nobles will not arrive until you mint a large quantity of coins, they are somewhat of a necessary evil. It is possible, however, to gain the various coin-requiring nobles by minting commemorative coins.