Currency

When bartering for goods and services no longer meets the needs of commerce, the sentient beings of the Realms turn to using items with a more universal value, namely precious metals, gems, and some minerals. Metals are rarely found in their pure form in nature and require significant energy and effort to refine and purify them. In general, the rarity and the amount of effort it takes to produce a given metal determines its worth. Sometimes this formula is modified by a particular property of the metal, or by a widespread use (and therefore greater demand). Gems are even rarer than metals and require great skill in mining, cutting, and polishing. Gems have great value because people desire them for their beauty and often wear them in jewelry. The arcane Arts also require certain gems as spell components which increases their rarity even more as they are consumed in the casting of powerful spells.

1st Edition Currency
In the 1st Edition Forgotten Realms Campaign Set