I'd already given that some thought - the foot does look exceptionally good for c. 1820 - 30, and must admit that most of the Georgian pieces that I see carry some damage, and heavy wear to the foot, usually.
However, as Roy has said this is a lovely piece of cut glass whether it is C19 or C20, and a lot of work has gone into the cutting, so very desirable however you look at it.
So that makes three of us who like cut glass