There is a protective coats like "clear coat" and "clara guard" in the market. It won't help you to avoid a damage, when you drop your phone, like a bumper, but will help you to avoid scratches and not to spoil a look. Such coat will add some thickness to a back cover and avoid the scratches on a camera plate. Clear Coat for Lumia 820 (you obviously should look for a specifically Lumia 820 full body protection, not just screen protection) also have a stickers for a camera plate. And yes, it will turn your phone into glossy look, if you have a matte color (like a black one). NOKIA CC-3040 (protection cover) and NOKIA CC-3041 (wireless charging cover) will also keep your camera intact because of the extra thickness. Both CC-3041 and СС-3040 are matte, even if the default cover (CC-3058) of this color is glossy (for example NOKIA CC-3058 Cyan is glossy and the CC-3041 Cyan is matte). You can use any screen coat to turn the phone screen down without worrying about scratching the screen.