Help please if authentic or fake. Was not sure what to look for. It was my first time to buy a vintage Omega.
It's fine. Omega Signed Crown, and not a replacement crown. It's uncommon but can be seen from time to time. Nice first Omega Watch, If you intend to wear it often you should let the Watch be serviced. Don't let it be serviced by Omega, but take an independent Watchmaker instead. Omega will often change parts like the dial and be more expensive.
Great first purchase! Those Omega symbol at the top variants appear from time to time and are legitimate.