From Ardrana

By use of the color spell, the caster brings color to an object. It can restore faded hues or tinge those already colored with a different hue. Thus, dull or faded fabric can be brightened, pigments restored, or even hair or skin changed to another color. The effect must be renewed every 30 days.

Note: This spell originally appeared in this form in Unearthed Arcana for Advanced Dungeons & Dragons from TSR. Its use here is for the purposes of providing context for the campaign only.