Extraordinary Old Trompe-l'oeil Bottle In Cut Crystal

I hope I can describe in words what I see when looking closely at this extraordinary bottle.
The bottle has an egg-shaped recess inside, so that the liquid it can hold is considerably less than the amount in a bottle of the same size but without this cavity. but, once completed, the "cheating" is invisible.

This is a very cunning ploy and particularly clever from the point of view of technical implementation.

The bottle is extraordinary because of this detail but also because of the exceptional quality of the carving.

I think it is a bohemian object from the first half of the 19th century.

For more detail photos, you can check: https://www.dropbox.com/scl/fo/fuuxu2el14wgip0o8fc0j/ANfm9Kf8nVB96REWNNUFX9o?rlkey=4n1vp1hpesbdlld7grs3b8tde&st=ueroxalb&dl=0