I've heard about these just recently and I've heard wonderful things about them. I have been "blessed" with cluster teethers -- each of my kids got teeth in spurts of 4-8 at a time (I'm not kidding -- Badger is right now getting 8 teeth at the same time). So instead of 20 weeks of crankiness, I get maybe 4 weeks of 5x the crankiness. Good times, great oldies. At any rate, with teeth numbers 9 through 16 popping through, I hope my kids' teething days are numbered.
So anyway. Amber. It's apparently analgesic when worn against the skin and they release healing oils. Not teething beads like you see but meant to be worn close to baby's skin so that they're not gobbled up. The necklaces are supposed to be quite safely made, so that if the cord does break, the beads don't come off.
Something to perhaps look into if anyone's teefers are giving them grief!!!