Scratched crystal on Omega Deville 166.033

Hi all... hope everyone is having a great weekend. I found a piece I really liked and am close to purchasing... until I saw closeup images of the watch. That scratch on the crystal! Im not even sure if it's a crack through and through. Guys, with your experience, can something like this be polished off? Been searching on ebay for a replacement crystal. Also, those bluish hues on the case, on either sides of the crown... can they be removed? I asked for images of the movement (likely calibre 565) and probably post 1968 model ( I read somewhere that prior to this period Omega printed Seamaster Deville... After '68, it was just Deville). The dealer couldnt supply movement images as he was unable to open the front. He's quoting US330. I don't know any other way (if there is!) besides the recommended tool 106 as written on the caseback. I've read about burgeon knives. Any good ? The image of the case on the opposite side of the crown, has some gap there though.

Crystals are easily replaced. Watchmakers should be able to source it easily.

If I'm not wrong, it's a monocoque case so you have to open it by removing the crown. It's really tricky, you should bring it to a proper watchmaker. You can see that someone has been trying to pry it open.

....hence that gap there.