Different colors can have different effects, learn the differences here.The color of an item can have drastic effects on any spell you cast, and generally on your day to day life.
Many times spells will require a certain color candle or colored pen or something else of color. The color is not chosen randomly, instead, each color has certain properties which can help to enhance the effects of a spell.
Sometimes just wearing a certain color can also effect your life. Here is a summary of the more powerful colors in magic.