Need help Identifying marks on ring

There are approximately 40-45 diamonds, approx.02-.03c each and 1 - 2 mm each (look clean under 10x and white) and the ring weighs 21.4 grams 18k and is a size 9+. It is marked 750 and there are some other makers marks inside (looks like "AL 1772" that I can't quite get a clear picture of.

My mother bought this in Venice Italy about 40 or so years ago. I am trying to figure out the maker or any other information about it. It is really big, 32 mm long and 25 mm wide. Sits 9 - 10 mm high off your hand. The design reaches around the sides and the back is thick 3mm wide.