The beads on the bottom row are the ones I'm questioning (should have put them on top) and they do not have a core. The feature that seems unusual is the relatively crude appearance of the twisted cane decoration. But one opinion I received said it looks like the red glass has degraded from age and / or burial, leaving the decoration sticking out. I've never seen this before.
Since we've seen so many examples of artificially aged beads I was not sure these are Venetian. Would be interested on any similar examples you've seen yourself.