The rear "camera glass of the HTC One X + is known to be very sensitive and was with me in spite of most careful treatment of cellphones (always in Silicone Case - could never really be on the camera lens) after 6 months so scratched that in pictures with backlight (or light sources Picture) no useful picture more was possible.
The "glass" (just plastic!) Has to be protected at all costs if you want longer enjoy this really very good mobile phone (even the camera makes a phone part - when new - quite useful pictures)!
The sapphire crystal fits perfectly on top of the original lens, and can be glued with a tranparenten adhesive (eg Pattex repair extremely) (minimal use adhesive - is supposed to only a uniform thin layer between the glasses give and not sideways rausdrücken). If one does from the very beginning, the matter is in 5 min., And has done for years no more trouble! I had to remove the back cover, detach the plastic part, mirror polishing and then glue it back with protective glass top - it cost 3 hours (and a lot of sweat to break anything).!
Although now no optical compensation more is on it (with the scratches buffed), adhesive layer + protective glass have been added, the images can be re-described as very good (I do not see any difference from the new state of the mobile phone) - and scratches I have (so far) no more!