Thank you for you insight...here is some complementary informations:

Glass bead, quite large, size is 32mm X 25 mm and another larger one (exact same color) ...

Conical asymmetric "perforation" dia. 0.8cm and 0.4 cm on the other side.

And came together with 20th (19th?) Century warring states beads copies.

With signs of burial (could also be chemical treatment?)

Not so common since I have seen only two specimens in 17 years collecting Chinese beads.

Collected in northern China, manchouria