I saw this in the charity shop some weeks back - it was still there today, so for a couple of quid I invested heavily. But the point about this one is the shape - how often do we see square cut glass bowls - at least I don't - sadly there isn't a backstamp. The cutting is quite sharp, though I'm sure the piece isn't remotely old - at least it lacks wear but suppose it might have been in Granny's cabinet for half a century - the colour is very bright and white. Not only is the shape unusual, but the upper half of the bowl curves inward, so how this was made is unclear - likely it was a moulded blank then subjected to a lot of work. There is a substantially deep single mitre that runs around the middle of the bowl.
I don't expect an attribution/maker so really this is just for show and to share something that I think is unusual in the world of cut glass. Size is c. 20 cms. square and something like 8 cms. high.