I don't allow those in my daycare. I don't allow jewlery of any kind on any kids, period. I don't want to be responsible for it being broken if another child grabs it, lost, and if it breaks I don't want another child grabbing it and putting it in their mouth.

I personally don't like those things, there is no control of how much their body is absorbing and I personaly don't think they work and are a money grab...but that's jmo.