Yup. Chinese freshwaters..sometimes called screw pearls because the rings look like screw threading. They were the only big pearls available a few years ago but now would not be worth much at all, although some still like them for their eccentric variety and non-symmetry.
As a point of interest, these pearls, though inexpensive, are nacre all the way through. The mussels were implanted with a bit of mantle tissue only (rather than a round bead).
This makes them very durable, highly suited for daily wear.