The rear cover has two plastic decorative parts located on the top and at the bottom. The surface treatment process for such decorative parts is different from that of the metal part of the rear cover (spray paint for the decorative parts and anodizing for the metal rear cover surface). There are minor differences in the color of the decorative parts and the metal part of the rear cover (for all phone colors, including black, white, and gold). This is normal and does not affect any of the phone functions.