Vintage Seamaster first purchase need help

[LevelJames]

Thanks for the add been browsing the page and now i found a watch i would like to buy i need your help
Its a Seamaster automatic De Velle and i am trying to work out the year as they wont let take the back off as its at a auction , i am not sure if its 18k solid gold or gold plate and what its actually worth in the condition its in
The auction is actually in a few hours so if i dont hear from anyone i wont go ahead and buy it, i am sure another will come up again

 

[TexOmega]

Early 1960's

And I would pick GF if you cannot verify it.


$3-400 USD if you verify it actually has a good movement