Simulated Opal Stud Earrings These Stud earrings are handmade with 8mm Simulated Opal Cabochons set in a 925 Sterling Silver Gallery "Crown" Bezel. Oxidized to a Vintage Silver finish. The posts are heavy duty and slightly longer than standard (.036/19 ga. x 7/16"L). Two types of 925 Sterling backs are included for preference or just to have a backup pair (Rubber core bullet style and traditional friction catch). Shipped in gift box. Opal is the birthstone for October.