welcome to the board, Martyn is probably right, 'made in Italy'
Im no expert on Murano (or anything really
but having a quick look in Leslie Pina's book, circa fifties glass,
it has similarities to Venini, Murano, pieces, and the 'm' in made, reminds me of script from
'Venini' that i have seen.
The book says pieces were acid-stamped 'Venini Murano made in Italy'
Just a start, hopefully someone will give you more ideas, maybe a good idea to ask a moderator
to move your post to the 'Murano board'
ps sometimes Venini is stamped on the inside rim of vases, worth checking