Gold Filled Kidney Shaped Earwire. Avoid worrying about your earrings slipping out of your ears with these gorgeous gold-filled kidney earwires. Their simple clasp makes them perfect for kids and anyone else who is afraid of losing their favorite earrings! All you need to do is add your favorite charm or bead to these versatile earwires for an element of your unique personality. Gold filled wire has a raw material base metal that contains a layer of gold (usually 12 or 14 carat) that is equal to 1/20th the weight of the base metal. This layer is electronically bonded to the surface of the base metal and is much thicker than plating.