Vintage Blue Plastic and 14 buy Karat Gold Department Store Earrings

This seems like such an odd combination these days but it was no big deal to use real gold on costume jewelry up until the 1970s or so. This is a pair of department store post earrings for pierced ears, still on their original card. They're a pair of blue plastic ovals measuring ~ 3/4" long by 5/8" wide and have a raised edge channel going through each that contains an S shaped strip of gold. The gold "S" measures ~ 16 mm long, 5-6 mm wide and 0.5 mm thick. I don't have a way to test these but trust they are on their original card (see photo #9).