I think sculpture is the right word.

How neat is the inside bit of the hole, John?
I have a bit of a thing about holes in glass items - they're difficult things to achieve in hand made glass, bits of the hot metal have to be cut, shaped and then joined up with each other.
If the join is neat, that can be an indication of quality.
Unless it was made using newer moulds in an automative process.

What exactly, does the base look like? All completely flat and shiney or slightly dull? Any marks there at all?