The largest I've passed was about 4mm. It's the most painful thing I've ever felt, and it took weeks to work its way through, even with the Flomax. Crying, moaning, writhing on the bed in pain, pissing blood. Malicious looking little thing. Looked like the ball on the end of a morning star. I passed two of those at once one time.

One tiny stone had me calling an ambulance. I thought my appendix had burst or something. I passed it later that day, and I almost missed it it was so small. Evil little bastards.

I had a 6mm one for just over two weeks. There were times when it just got stuck and that wasn't too painful. Then it would start moving again and it was agony with no warning.

My first child was born during those two weeks and, thankfully, the stone stayed put during the birth.

Aww yeah, kidney stones suck. I'm glad I could mitigate them by becoming vegetarian and consuming less salt. Doesn't work for everyone though. Which kind of stones did you have?