Solid OakSolid Oak Steampunk Large Vial Glass Pendant (1 Pack)

How large is the hole in the neck of the bottle? In millimeters, please.

What is the diameter of the opening of the vial? I have some pearls, the largest of which is 6 mm in diameter, that I want to display in the vial.

Is the bail big enough to fit a chain through?

Are the metal end caps screw on or do I glue it? What glue works best?