Hi, I'm trying to work out exactly what omega watch I have, however I did not buy it as it has been passed on from my great grandad to me. This means I don't even know if it is legitimate, however the storey behind him getting mostly backs up it being legitimate. What sort of things do I need to post so I can get some help identifying it? I know that it is and Omega Constellation, Calendar and it says automatic chronometer on the face, I believe the straps (unsure of the correct term for the part that goes around your wrist) are custom because I cannot seem to find them on the internet any where. The hallmark is DS&S and there is what looks like a little crown next to an 18 stamped into the metal which is golden. Please help me!