Harbor moon

A harbor moon was a Waterdhavian coin worth fifty gold pieces inside the city, but only thirty gold pieces elsewhere. It was typically used in bulk purchases within Waterdeep.

Description
The coin was shaped like a crescent moon and made of platinum with an electrum inlay. It had a central hole to allow it to be strung on a string. It was about 3 in (7.6 cm) long and the central hole was large enough to fit a nib inside.

History
In the mid‒14 century DR, a harbor moon was worth only 2 gp outside of Waterdeep.

In the late 15 century DR, harbor moons could be exchanged for other currency in the Palace of Waterdeep with no exchange fee, but the line was so long that appointments frequently needed to be made a day in advance. The Guild of Trusted Pewterers and Casters and the Jewelers' Guild were also capable of quickly and reliably performing the exchange.