Thought Id throw in my 10 pence worth. Im a diver for my living and even we don't use 7mm gloves when it gets really really cold in the UK.
Only time I have used them was when I was in Norway, 100 miles inside the Arctic circle.
50 degrees is quite warm, so a good set of 3mm gloves would keep you warm. I find with wetsuit gloves that quality is best over thickness. I had a set of 1mm scuba pro gloves and they kept my hands warm in Scotland down to depths of 30m in November, pricey gloves but very well made.
Something like this would be ideal -
http://www.ebay.co.uk/itm/XCEL-3MM-DRYL ... 235wt_1140
I have a Xcel suit and it is amazing so I expect the gloves are the same.