I have what I believe is a 1957 omega seamaster 300 all original. My grandfather recently gave me this watch and I was trying to find out more about it. He told me he got it in 1947 for $60. Though, through my research I think he got the dates mixed up and it looks like a 1957 to me. I took it to a couple of watchmakers and they were unable to tell me much about it. Help.