Craig,
I think you were right about it being Mazzega, probably from the 50's/60's. I haven't seen this exact chandelier before, but I have seen Mazzega with that amber tinge combined with clear glass and similar metal fittings. It's really hard to get information on chandeliers, particularly from Murano. It might be worth contacting I.V. Mazzega, as the company is still operating in Murano, as far as I know. They are almost definitely authentic. I've not seen anybody trying to reproduce modernist chandeliers from Murano. They would still cost a fair bit to make. If you look at some of the high end re-sellers of similar chandeliers, you'll notice the prices for a piece like this are very high.
I think it's great and you're lucky to have it. I know mine will go with me wherever I go, or the kids will fight over who gets it.
David