Gold filled 1mm hoop earrings inner diameter is 40mm new with box. Gold Filled jewelry is made by wrapping layers of solid gold (14K, 12K, or 18K) sheets around a base metal (usually brass). Unlike gold plated jewelry, gold filled jewelry actually has a measurable amount of gold in it. This process of adhering solid gold sheets makes for jewelry that does not tarnish, peel, chip or discolor.