These are noted as CR opals (synthetic or lab created) in the product description so there should be no surprise there. Although others here seem to differ, I've seen "fake" opals and I think these look like very expensive fire opals. Most people can't afford those and settle for the milky opals with only a spot of "fire" and so think that's how opals should look. In any event, I love the opals and the silver setting is very fine and sets of the stone beautifully. I measured the stone as best I could, minus the setting, and they are about 3/8" long and wide (or not quite a half inch). If they were any bigger they probably *would* look fake. The back of the frame setting is marked .925 (sterling silver). My only disappointment is that when I came back to write this review, the price had dropped by almost $6.