Copper

Copper was a precious metal used in Faerûn as the baseline of most currency. When used as currency, it was usually cast into copper pieces (cp) of a standard weight.

Worth
Most coins in Faerûn worked off of the silver and gold standard, with copper pieces (cp) being worth 1/100th of a gold piece (gp) and Silver pieces (sp) being worth 1/10 of a GP. Electrum coins were worth 50 cp (1/2 gp), and platinum coins were worth 500cp (5gp) in 1st and 2nd edition and 1,000cp (10gp) in 3rd and 4th edition.

Each coin was approximately 30.6 mm in diameter and weighed approximately 9 grams each (or 50 to one pound).

Conversion
Simplified: 1000cp = 100sp = 20ep = 10gp = 1pp