It's unsigned, but the shape - in smaller sizes and different finishes - is illustrated in the Venini catalogues as a mid/late 1930s Scarpa design. The quality is definitely there for early Venini.
It's 490mm / 19" in diameter, and is a very thin delicate sky-blue cased in clear glass (the blue is fairly even across most of the bowl - it's my rushed lighting causing the patchiness). The pontil mark (the 'white' blob in the centre of the bowl) has been carved out in several strokes.
Confirmation / alternative suggestions most welcome.