Ann Curry from the Today Show wears a very delicate necklace. Any clue what it is?

I have seen multiple stars wear these necklaces. It is a tiny thin necklace that is not very long at all. It has a pendant that is very tiny circle that hangs just in the knotch where her sternum starts and her clavicles (collar bones) meet. It is so delicate and beautiful. I love it, [...] http://bit.ly/bA6NKt