This compressed globe shape seems to have been more common prior to about 1910 - and Patricia's book shows similar shapes by Richardson, Webb and Stuart, all of which appear to have been made prior to c. 1900.
Maximum diameter is 12 cms. (4.75") - height is about 9.5 cms (3.75") - and think I'm counting 13 ribs. from the optic moulding.
Rim is ground/polished and bevelled both edges, and as can be seen wear is quite extensive - so could have some reasonable age. When flicked it sustains the ring for quite some little while, so good bit of glass methinks.
The colour looks to be a good match for Stuart's blue from that period, but I'm not too sure about the size matching, and it may well have nothing to do with that factory, of course - I'm guessing really.
Thanks for looking and if Patricia has the time, perhaps the lady might possibly help.

Ref. 'THE
Curious HISTORY OF THE BULB VASE' - Patricia Coccoris - 2012.