Horseshoe appears to be made of brass. It is unknown if it is gilded with gold or is gold filled. On back the pin is soldered directly on the horseshoe. P.S.C.O. is stamped onto the pin. It stands for Plainville Stock Company, of Plainville, MA; manufacturing jewelry since late 19th century. The decorations on the front of the horseshoe represent furrows where the nails were hammered into the horseshoe. Pin is 2 1/2 " long by 9/16" wide.