Would a 3mm hole be a feature of something made to accommodate a Pandora-style bracelet rivet?

The apparent lack of any sort of buffy grit in the holes makes me skeptical about these being old Chinese glass beads.

The only way to remove mandrel release of any sort - soot, clay, whatev - is by drill polishing the hole, yes? Unless, like the Venetians, one uses copper tubing and then dissolves the copper with industrial strength acid?