Did a bit of research and found nothing really useful. So the problem - I noticed little dirt and tried to pull it off from the edge with my nail, but it made it only worse, I have now the dirt on the whole edge (see picture). I tried fingers, microfibre (dump and dry), foil to clean it - no luck. The dirt almost unnoticeable, but once you know it there it drives me crazy, considering my phone only one month old. Anyway I'm not obsessed with stuff, and after couple of month it wouldn't bother me, but perhaps this topic would be useful at the end. I heard some people are using iklean - would it help? Also some propose to use toothpick or needle, but I'm scary I might damage glass or plastic. What do you think?