I have never had anyone take this spell. It seems kind of useless unless you want to leave a marker for others to follow you or something.
It says you can change the color or make it clear but does not mention making it glow. You can freeze it, so I might allow it to act as a prism and filter light but I would rule that it cannot glow on its own. Take light cantrip for that. I would be interested in seeing if others have cool ideas for it to make it worth taking.