Yes Joyce the ones you show are Venetian jewellery beads, no doubt of that.
But they are not made the same way. Yours are one colour with a layer of another transparent colour and the avventurina added on top of one half, before any swirling was done.

The beads shown at the start of this thread are made with half the pale colour, and half the darker colour, all the way through.
If you broke the bead it would be clear. (or happen to get a string with some already damaged, of course)

Stefany