These Elegant 18-Karat Gold Over .925 Sterling Silver Earrings Feature Vibrant Lab-Created Amethyst Gemstones For A Timeless Birthstone Design. Lab Amethyst Gemstones Post Back Closure Material: 18-Karat Gold Over .925 Sterling Silver Imported Earrings Drop Approximately .30In It Is Customary To Treat Most Gemstones To Achieve Enhanced Color And Durability. Some Of These Treatments May Not Be Permanent, And May Require Special Care.