Necklaces??

I'm sure it's been mentioned on the show or somewhere on this board but I've never heard it. What I've always assumed is that there's a tiny microphone in that big bead. Their voices seem to come out loud and clear and there's obviously nowhere on their bodies where they can hide a microphone! The first time I watched this show a couple years ago, I thought it was just one of the women who had that necklace and I was surprised she was allowed to keep it but then I saw that the guy had one just like it so I figured it was the mike.