Old enamel silver S F Iduna (Norse goddess of youth) social club brooch pin.   Inscribed on the back F.V.O. of Iduna - Mrs. P.V. Nelson.    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.