Check if back glass is replacement or original

If you had the back glass on your phone replaced by Apple (or an Apple Authorized Service Provider,) then they used original Apple parts. If not, then it's pretty much a guarantee that they use non-Apple parts.

If, instead, you are purchasing the iPhone used from some third-party, have them provide you with the Apple repair information to prove it was performed by Apple. Otherwise, suspect it was done by a third-party, and it would no longer be covered by any Apple warranties.

Hello ~ Why? Is there an issue ? Where did you buy your iPhone? If you have doubts make an appointment and have Apple check it…

Genius Bar Reservation and Apple Support Options - Apple

~Katana-San~