Extended Colour CorrespondancesMagenta: Combination of red and violet that oscillates on a high frequency; energizes rituals where immediate action and high levels of power or spiritual healing are required.
Indigo: Color of inertia; stops situations or people; use in rituals that require a deep meditational state; or in rituals that demand Saturn energy.
Royal Blue: Promotes laughter and joviality; color or loyalty; use to attract Jupiter energy, or whenever an influence needs to be increased.
Light Blue: Spiritual color; helpful in devotional or inspirational meditations; brings peace and tranquility to the home; radiates Aquarius energy; employ where a situation must be synthesized.
Emerald Green: Important component in Venusian rituals; attracts love, social delights, and fertility.
Dark Green: Color of ambition, greed, and jealousy; counteracts these influences in a ritual.
Grey: Neutral color useful when pondering complex issues during meditation; in magic, this color often sparks confusion; it also negates or neutralizes a negative influence.
Source:
http://www.ecauldron.com/spells/multi01.php