Using the appropriate colours in candle magic and spellworking makes a difference, as it strengthens your focus at both conscious and unconscious levels and enhances your chances of success. The colour correspondences listed below are suggestions only - based on tradition and experience.
White
White candles can be used for any work of meditation or magic. They can be used in place of every other colour except black. White symbolises positive energy, innocence and good will, and is used for purification, peace, lunar energy and spirituality, protection, service, truth, wisdom and sincerity. White can be used for Lunar workings.
Black
Black is the colour associated with the planet Saturn. This is a good colour to use for grounding, exorcism, banishing, endings, protection, healing severe diseases, and absorbing and destroying negativity. Also good for some forms of meditation.
Brown
This is the colour of earth, and is good for earth energy working, grounding and earth connection, healing animals, stability, home and physical objects.
Red
Red is associated with the element of Fire and of the planet Mars; the planet associated with energy and war, so this is a good colour for physical energy, strength, vitality and for courage. Use this colour for issues of passion (both sexual, and the 'burning desire' type). This colour is also good for increasing personal power.
Orange
Orange is the colour of Mercury, and is especially potent when working with things associated with Mercury, or the Egyptian Neter Thoth. Use this colour for issues dealing with business, magic, communication, and medicine (drugs, surgery, etc. as opposed to "healing"). Also for friendship, learning, stimulation, strength, energy, enthusiasm, luck, adaptability and attraction. Orange can be used for legal matters and justice.
Yellow
Being the colour of the element of Air and of the Sun, use yellow for intellectual pursuits such as study, concentration and learning. Also, for attraction, persuasion, inspiration, joy, love, communication, confidence. Because of its connection with the Sun, this also a good candle to use for issues of beauty, harmony and balance.
Green
As green is the colour associated with the element of Earth and with the planet Venus, green represents growth, abundance, fertility and healing. Green is also associated with money so is a good colour to use for attracting money, prosperity, success and employment, and for financial matters. Green is used for good luck, will, determination and any goal requiring balance and renewal.
Blue
Blue is the colour of the element of Water and of the Planet Jupiter. It's used for serenity, peace, tranquility, understanding, and patience. This colour is also often used for healing, intuition, wisdom, meditation and harmony. Under the auspices of Jupiter, this colour can also be used for justice and legal matters.
Indigo
Use indigo for meditation, wisdom and self-awareness, flexibility, causing change, protection, and building psychic abilities, healing, and the unconscious mind. Sometimes called the psychic colour.
Purple
Sometimes called the cosmic colour, purple is associated with the Moon. You can use purple for power, meditation, ambition, spiritual development, psychological healing and healing severe diseases, psychic abilities, personal growth, and to connect with cosmic consciousness. You can also use this colour to find things that are being hidden from you.
Rose
Use this colour for love, friendship, work, creativity, honour, morality, relaxation, happiness, affection, perception and clarity. Also good for releasing depression.
Gold
Gold is another Sun colour. Use for action, force, growth, love and healing. Also for attracting money, prosperity and wealth, and for protection.
Silver
Silver can be used for anything to do with the Moon, including receptivity, intuition, development and meditation. Also useful for self-healing and protection.