Is this a genuine early Venetian Paperweight?

This labelled Murano Venetian Paperweight is 70cm in diameter.
It's flawless.
It's also unusual, hence I'm struggling to find one similar so I know what I've recently inherited.
If there's any kind soul out there who could help me understand the provenance and estimated value it would be greatly appreciated.
Sincerely, Paul Whitehead
(LONDON)
pfjw23@gmail.com
07582469001