I just saw your beautiful turquoise necklace. I happen to have a similar bead like one of yours with the carved eyes and a vertical line down the middle and sloping sides. Mine was purchased in Xian China about 10 years ago.

Attached are 2 pics of the bead front and back. Somehow I think this bead is quite old if not ancient. There are authentic looking toolmarks in the perforations as well as around the eyes and the patina looks ok.

Think you are lucky to have quite a few on your strand ! Care to share the source ?

Sallie