The glass is kind of tinted. It has a whiteish tint when switched on (clear) and very white when switched off (opaque). When switched on, it is not completely clear, so adding tint will make it even less clear. Also, the combined tint color should factor in the original white hue. Some people like brown tints, so that would appear more tan. A black tint will appear more gray.
As a note, if the shade is open and the glass is off (opaque), a lot of heat and light come into the cabin because the sun is pretty strong. I have to close the shade whenever I'm driving mid-day because my head gets hot. The seats and AC keep the rest of me cool, but the shade is the only way to get away from the radiant heat from the sun.