Rock Crystal w/ Diamond & Sapphire Earrings 18kRock Crystal w Diamond Sapphire Earrings 18k. These Hollywood Regency Modern Earrings are bold and dramatic. The earrings are constructed in 18 karat yellow gold and feature large carved quartz crystal drops creating a style commonly referred to as a door knocker earrings. The link connecting the two quartz crystal carvings is set with round sapphire and round brilliant diamonds in a pave style. The diamonds are interspersed through out the sapphires