my dating was based upon an accumulation of small details although i could be misinterpreting them....first is the issue of form which is clearly straight out of the american brilliant cut glass era which ended around ww1. certainly forms can continue to the present as one can find at waterford but the major glass makers tend to focus on contemporary pieces and then ones not so complicated to make. the piece is unsigned which if it were vsl modern i would expect to be signed. i have not been able to find a comparable piece of recent manufacture - the ones i have seen like this have been dated pre 1930s.....
if you have an example of recent vsl which fits this design i would be interested. of course it may not be vsl....