IIRC The home button and the bezel were made by different manufacturers IIRC, and the two plastics aged/coloured at different rates. It took them ages to get

IIRC The home button and the bezel were made by different manufacturers IIRC, and the two plastics aged/coloured at different rates. It took them ages to get it such that the button and bezel will colour match perfectly. Easy to do with black, very difficult with white.