Google Amber teething necklaces and you will find heaps. Just make sure that they are Baltic Amber.
My Dd's is designed to break under strain, so she shouldn't get it stuck. They are also individually knotted.

I too am thinking of getting one for myself. i am still wearing a harmony bell that I got when pregnant, and will leave that one till I finish breastfeeding, as she loves to hold it while I feed.