It is a lamp globe, probably 1920s. We inherited this one from grandparents. T he original globe was broken and it took years to find this as replacement (pre-internet). Then we broke the base!
The opening on the base is about 2 3/4 inches. Sorry, but for some reason the pictures will not post. Ours is a table lamp with a small figure beside the globe. If you are interested I can try to send pics email.
Fantastic lamp you have there Dogo. What threw me off is the open pontil inside this amber globe vs your globe not having one. The mouth of this globe in 3⅛inches inner diameter and 3⅞ outer diameter. I should add that I am no where near open pontil aged trash but here this is?