oh gosh - cardinal sin Rose

- you've not told us what the base looks like i.e. modern mould finish, snapped pontil, ground/polished pontil - extent of wear, if any, and whether the foot is perfectly round or slightly irregular. Also, are there any swirl marks - either in the bowl or foot.
I think you'll struggle to get an attribution for this one - wines in uranium must have been made in their thousands up until the late 1930's, and I think the engraving is of a stylized flower, rather than depicting some particular species of flora. However, I think it's attractive, and as you say, shame about not having the other five. Drinking glasses are always interesting, and they consume so little space. Nice piece.
Assuming absence of any wear, then I'd plump for quite modern, eastern Europe possibly.