Audemars Piguet

Dear friends; Please look at on top of the rubber bezel,we can see there is circle line on top of it. Its G series. Any body facing same problem? Can any body explain what cause this problem?...  

I would say that as rubber seems to absorb oil/grease from your skin the rubber that frequently comes into contact with your fingers is going slightly darker/shiny. As rubber is more 'fluid' than metal I think there is a very slight depression in the surf... 

Has it come in contact with anything other than water, like an oil or lotion perhaps? I used to own one and had it in the ocean and other water and it never showed that.

under magnifying glass I can see that the darker line more flush/deeper then other part. I never used lotion on my wrist or clean the rubber with liquid except wash it with baby shampoo, i never wear it under the sun (example for golfing) or for swimming.... 

Never seen this before. Thanks for the photo. I think the other responses were right on target.