A moon was a crescent-shaped coin minted by the city of Silverymoon.
Circa 1358 DR, the moon was a shining blue crescent-shaped electrum coin, valued at 2 ep (1 gp) in the city of Silverymoon and 1 ep elsewhere.
By 1372 DR, the metal had changed and the moon was a shining gold crescent. It was accepted throughout the Silver Marches at a value of 2 gp.
Then, in the late 1480s and early 1490s DR, electrum was in use again. Still a shining blue crescent-shaped coin, it was valued at 2 unicorns (platinum pieces) in Silverymoon, and 1 platinum piece elsewhere. In addition, there was also the eclipsed moon, which consisted of a moon stamped with a silver wedge to complete its round form. It was worth 5 unicorns in Silverymoon, or 2 unicorns elsewhere.