You've got a "Sheaffer Balance" there. The color is known as "Marine Green" and 1930-35 would be a fair estimate of approximate dates for that color. Your clip is a "humped" clip with a radius or hemisphere end. I think you've got a mid 1930s era pen there- as near as I can tell (looking at the color and the clip). I think you're closer to 1935 than to 1930 with that combo for sure.
It looks like the nib is a Feather Touch, but I can't read it exactly in the picture. Looks like that though. The nib appears damaged in that picture- but often they can be fixed by a proper repairman.
Beware of discoloration with Marine Green- it can turn to a brownish color if you have a regular rubber sac in there that releases gasses. You may want to put a silicone sac in that one, if you get the chance- the color you have there is well-preserved.
For some more information pay a visit to Richard Binder's website:
http://www.richardspens.com/ref_info/balance_profile.htmhttp://www.richardspens.com/?page=ref_info/balclips.htmThese pages have some helpful info in dating your pen, as well as assessing the size. I'm poor with pictures, but it appears you either have an "Oversized" Balance or a "Standard" one. I can't tell just by pictures though- so take a look at the reference information on that page.
In any event, you've got a very nice pen there and a real "keeper". Just make sure you get a fresh silicone sac put in, and a nib repair.