I don't know, but IMHO rather not

I have never seen this type of sommerso in a - confirmed - Flavio Poli piece. (And I have looked at
many when I researched my Poli vase)
Not the delicate and sparse use of colours I would expect...
That ebay seller doesn't seem to be the most reliable resource either, he cannot make his mind up: in the title he says Flavio Poli for C.O.V.E.M. (whatever that is), in the description AVEM.
Nice vase, though, but I would think more recent than 1950s...
Michael