Difficult to tell from one photo only, but It looks to me as if the enamel has chipped away from the dial and the plate below exposed (it seems from the photo as if there are large pieces of enamel floating in the case)
I took a similar watch to Cartier and they resurrected it for just under 1000 USD - complete overhaul with new dial, hands, crown, etc
Here's the thread I started about it:
https://omegaforums.net/threads/found-a-little-cartier-tank-but-is-it.97239/Click to expand...