Retrieve the Cats Eye Emerald from one of the Venture Co. Overseers or Enforcers for Wharfmaster Dizzywig at Ratchet.
Being Wharfmaster of a busy port like Ratchet, I keep my finger on the pulse of information. I know all about the exchange of goods and money between here and Booty Bay.
The latest bit of news I've heard is about the Venture Company's Boulder Lode mine northeast of the Sludge Fen. One of the miners discovered an emerald the size of your fist. I know a few buyers who'd be interested in getting their hands on something like that, and I'd be willing to go half and half on its sale.