Old sterling silver enamel yachting or nautical club burgee flag brooch pin.   Marked sterling on the back, N encased in a circle, and Chicago.   Measures roughly 1 1/16" x 2 3/16".    I don't clean items I leave the original Patina on it. I have other collectibles in my eBay store and feel free to take a look.  Once again thanks for taking a look.