Chew Beads. These are supposed to be the very thing that babies like to play with and chew when they're teething. They're rather pretty and having seen babies pull and tug at normal jewellery I think these would be less stressful to wear. They come in a range of colours and even in bracelet form. Obviously you wouldn't leave your baby alone with any string of beads and you'd have to be very careful if the string broke but they do seem to be very strong and sturdy so I imagine they'd be quite a safe way of occupying your baby when your out for coffee or lunch and have your little one on your knee.
can be ordered from the US.