Have they ever worked together?
I'd say it's a cast, but I'm not seeing Vallein in it. The face is a bit more Blowzone-style (originally african art, modified by Picasso and now a generally popular style), to my eyes, but I am not remotely up on artists who cast. Blowzone was run by Iestyn Davies, but he doesn't make glass any more.
The colours are a bit "in your face" for the artists I do know of.
But it looks like a good quality cast.
You might find more searching using the word "cast" rather than paperweight or sculpture.