Rings, like engagement/wedding rings, can take quite a beating. You need a hard stone or it won't really last very long.

I have a lab Ruby in my engagement ring and then lab diamonds around it. The lab Ruby is a good alternative because it's a hard stone! Sapphires and alexandrite are also just as hard and could be good stones in a ring you'd wear everyday.

It's more dropping or getting scratched, but I'll admit I've never seen opal break.