These opal stud earrings – 5mm, are set in sterling silver and make for a perfect sized stud. These opals were mined in Spencer, Idaho, and come in a array of colors. No 2 pairs will be alike. These classic stud earrings are eye catching and made right here in Philipsburg, Montana. These are versatile enough to wear with any outfit. Know someone with a birthday or anniversary coming up? Spencer, Idaho opals make a fantastic gift! They are the birthstone for October.