As for the color, that’s the side effect, usually favorable as it is far more noticeable, of laser-etching, especially on plastic – laser etches the desired image by burning the surface up to a certain depth (depends on how much power you give it), and every material will give you different color when burned – for example aluminum would have dark-grey color, and copper will have a greenish hue because of the oxidation, and obviously the black polycarbonate has a light gray with a brownish tint color, depending of the intensity of course.

If you want to have the original color, you can remove the top layer with some reactive chemicals after it’s burned by the etching, or you could use a CNC to mill the etching instead of burning it with a laser. Either way, I wouldn’t dare to do this on my N9 without first trying and calibrating it on a dummy piece of polycarbonate.