Well, it's obviously a Seamaster. :wink::laugh: Looks a lot like a reference 398.0806 but without the rotating bezel that one had. If it's gold plated it's worth $300-ish, but wait for a member who's more informed on hummers to come along.
I have a few of those Omega f300hz watches but I havent seen many with the case that yours has. It looks similar to a case that Titus uses on some of their tuning fork watches but the one you have is gold plated OR solid gold?... If youre looking for a little info on the watch, I can tell you that its probably powered by a caliber 1250 (date only) The 1260 had the day/date feature. If you're looking for a case reference number, try having a watch repair guy take the back of the case off and you should be able to find that information on there. None of my Omega tuning forks have the *180<omega symbol> on the back so that's something new to me as well. Hopefully one of our other members comes along and answers that for you. As for the value of the watch, my guess is the same as Dennis's (user: ulackfocus). Try doing an eBay advanced search of completed listings on "Omega f300" and you'll probably get a better idea of what they sell for in todays market.