You are correct that the answer is "it depends", what I can tell you though is what it depends on.
The first thing to consider is your atmosphere. What light frequencies (colours) does it reflect? Which ones get through to the surface? Our atmosphere lets visible light through, which is one reason our eyes are tuned to those frequencies, but the scattering of blue light is why the sky appears blue. Note though that over time your vision would adjust to any ambient shading of the light though and adjust for it until it seemed normal.
The second thing to consider is the materials making up the ring and how they are arranged. If the ring is mostly iron oxide then it might be red, sulfurous compounds yellow. Ice might be white, or blue, or any other colour. But those are wide generalizations, just find out what colour the material reflects and you have it.
The final thing is the colour of the star. A red giant will naturally colour everything red, while a brighter blue star will shift things the other way.
So now combine those two effects, and you have the colour of your rings:
- In space you will see the reflected colour of the material as modified by the light the sun is putting out.
- From the planet additionally you will have the absorption and scattering effect of the atmosphere.
At night the rings would act a little like the moon, in that you would see the rings glowing to both the east and the west (although once in the shadow of the planet the glow would stop). During sunrise and sunset the illuminated part of the rings would be on the opposite side of the sky from the sun. Looking towards the sun it would potentially only be visible as a darker band if it moves in front of the sun.
The rings would be very useful for navigation, telling position and direction would be much simpler than on earth.
