I developed a heraldic system for colours in a campaign once, I'll just throw the quick version in here:

Black/Sable: Moral toughness, physical endurance, ruthlessness.
Blue, dark/Sea: Mysteries, danger, reason
Blue, light/Sky: Air, vision, beauty
Green: Youth/growth, pride, honesty
Orange: A taboo colour, associated with magic-induced calamity
Red: Power, dominance, activity
Violet: Magic, secrets, dreaming
White/Silver: Nobility, purity, death
Yellow/Gold: Royalty, ancientry, wealth