quite a coincidence that I should find something similar yesterday in one of my regular charity shop type haunts - and probably one of the oldest pieces I've had from this source.
Whilst not a preserve pot, thought it of interest to show in view of the colour which more than anything else convinces me it's period - a greyness typical of glass from the Georgian/Regency era. Lead glass and showing substantial wear on the foot, with a great ring despite being very heavy. Fortunately, damage is confined, as you'd expect, to the extremities of the diamonds, mostly on the body - the lid seems to have esacped for whatever reason. One or two small stones as usual.
This is almost certainly a lidded sweetmeat (no cut-out on the lid) decorated with mostly plain diamonds - three bands of prismatic cutting and serrations around the rim of body and lid and with what looks like a capstan stem. Although not cut too well in the centre, the 24 point star would suggest c. 1830 - 40. Overall height is about 7.25" (185mm).
All the features we've discussed for these things, plus the colour, convince me of late Regency:)