Perspex or Lucite. Possibly from factory of Alberto Polimeni, an Italian engineer who created unique "windscreen" sweetheart brooches in Eritrea during WW2 (circa 1942-50) for Allied forces, particularly the RAF. These brooches were hand-machined from Perspex, the acrylic material used for aircraft windows and canopies, often incorporating salvaged brass from RAF jacket buttons. And American coins, apparently! Sculptor Adolph A. Weinman designed the "liberty Dime" coin in 1916. He added a winged Phrygian cap to Liberty's head to symbolize "liberty of thought". The public quickly mistook the winged cap for the attributes of Mercury, the Roman messenger god, and the nickname "Mercury dime" stuck permanently. 1.5" tall not including ring at top.