Moved here from the game thread.
I’m sure What Exit? will have a more definitive answer, but we’ve been using blue for Sting and Curu’s blade since they glow blue on occasion. Most other magic items seem to be in green if anything. At least the part that breaks character. For example, +1 silver bullets. Spells seem to be in blue most of the time. Damage taken is in red. Other than that, it seems up to the individual.