Thanks so much folks for your quick responses. :hiclp:
Kev - the sulphide is indeed very close to one side. So much so, that if I hold it with the sulphide turned at 90 degrees, then I can't even see the sulphide, it "disappears" from view and I can only see the leaf swag. Its a really strange p.w. When I first spotted it in a display case, I was convinced that it had a flat side looking at it straight on and was surprised to find it was a dome shape when held. I will have another look underneath tomorrow in good light to see if I missed any other markings, or can make out what I think might be numbers. Its 2" high with almost a 2½" diameter base and weighs 380g.