The one I have is from the same year as yours, approx 1970 and is in the 29,6xx,xxx serial range and it looks pretty much exactly as yours does except the bracelet. If your hands have some paint chipped it could have been from being removed for a cleaning some time in the past.
It looks like the first photo shows the crystal having the Omega logo in the center, that should indicate it is an original manufacture part by Omega
I also wouldn't think about replacing anything except the oil.
I'm only judging by mine which I'm the 2nd owner of and know it's "0" maintenance history before I had it.
Perhaps someone will verify that the ring and dust cover are made of (non stainless) steel or iron and function as protection against magnetizing the movement. This is why they might show a little more oxidation.
- arif (registered) on May 5th, 2008-20:07 
