Nice dial. I've seen lots of examples (including mine) where the blue colour washes out and somehow recedes into the dial and back from the edges over time. I think this model came in three colours, the blue being the more uncommon of the three. Your are right to be questioning the colour as there are many coloured redial aberrations coming out of South East Asia... I LOVE the bracelet on these. It's very classy, sits beautifully and is very well made. For some reason I find it particularly tactile and often absent mindedly rub my thumb over the links when deep in thought.
King Crouchy is right, despite wearing big and bold it isn't very collectable. The 1020 movement is among the earlier 1xxx series that seems to be quite prone to malfunction..I wear mine carefully and sparingly but it's still had 2 visits to the watchmaker in 5 years. .I think Omega were nearing the end of their in-house movement production at this point (around 1973) as the Quartz revolution was in full swing.
I'm quite surprised they are even reaching 600 USD, that said, this one in such great nick I could see maybe +100 USD more, but 1200 is waaay into another Omega price bracket. You could get something a lot more special, say, a realIy nice constellation for that sort of cash.