Beautiful opal stones. They have more shimmering iridescence in the light than in the Amazon photo. I'm happy to add these studs to my jewelry collection because they're affordable and go with everything. The only thing I don't like is that the setting is higher profile than necessary. The stones are flat, so there is empty space underneath them. I will post a picture. It is a sturdy, 4-prong basket setting stamped with "925."