Hi and welcome
I don't know anything about this kind of glass but that looks like a bowl 'Ondines' in Cappa's Le Genie Verrier de l'Europe page 381 which is id'd as Marius Sabino and I think it says signed Verart moulded signature?
Does yours measure 34.5cm wide? Is it marked Verart?
In the book the bowl looks an opalescent purply blue colour, more purple than yours and it says it is opalescent. I don't know if these were copied or not by someone else?