14k Gold or Sterling Silver Blue Simulated Opal Ball Stud Earrings - 3, 4, 5, 6, 7, 8, 9, 10mm Unsure what size earrings to buy? 5mm is the perfect size that will look great on most people. These earrings are made of solid rhodium plated sterling silver and fine quality simulated opal. Our radiant simulated opal reflects back all the colors of the rainbow, easily convincing others it's the real thing. Made in-house at Beauniq Fine Jewelry in NYC.