Color Magic refers to the combined magical and psychological effects of color(s) while working spells. Psychologists have only recently begun studying the effects that color has on people, but magicians and alchemists have known of the power of color for centuries.
Using specific colors when performing rituals is not necessary. Using colors that correspond to the purpose of the spell or ritual can, however, vastly enhance its power. The easiest way to bring color magic into your ritual is to use candles. If you frequently perform rituals for a specific purpose, you may want to invest in candle holders, altar cloth, or other ritual supplies in the appropriate color(s). Many traditions favor ritual tools in black and white to avoid confused messages during rituals (among other reasons - see List of Color Magic Correspondences below).
When discussing how to use a particular magical tool, you will often hear about its correspondences. A correspondence is simply what something is used for. You would say, for example "White corresponds with purity" or "Black corresponds with grounding". Most magical tools (colors, herbs, crystals, symbols, etc) have more that one correspondence, so it is still important to use your will and visualizations no matter how many extra tools you have.
Also, correspondences (color magic correspondences in particular) are seldom absolute. When you choose your tools, make sure that the color matches the purpose in your mind. Green, for example, can symbolize both sickness and health. For healing, you would choose a healthy green. For repulsion spells (like a "Get this negative person out of my life" spell), you would want a sickly green.
White corresponds to spirituality, cleansing, purity, perfection, innocence, integrity, healing, freedom, opportunity, forgiveness, and acceptance. It is also a color of simple power. White carries the powers of all the colors. It can be directed towards almost any use, and can enhance the power of other color magic in spell work. It helps eliminate negative energy and creates inner peace. It is used by many cultures in purification rituals. It also corresponds to the Maiden form of the Triple Goddess.
Black corresponds to death, the Underworld, grounding, stability, mystery, and witchcraft. Black absorbs negative energy. Many people shy away from using black in magic, even going as far as to say "never use black". I do not hold to this. With its powerful associations to mystery and the underworld, black makes a powerful addition to any spell of divination or protection. Black is the color of the Crone aspect of the Triple Goddess.
Red corresponds to the Element fire, the Root Chakra, the God Ares, Mars, love, passion, sex, self-confidence, success, strength, creativity, persistence, energy, and vitality. It is often used in love and healing spells. It is also associated with grounding (the Root Chakra), and with any powerful emotion. Red is the color of the Mother Aspect of the Triple Goddess.
Pink corresponds to love, nurturing, tenderness, sensitivity, harmony, femininity and innocence. While red is associated with fiery love and passion, pink corresponds to the gentler aspects of these emotions.
Orange corresponds to The Sacral (Navel) Chakra, harvest time, happiness, excitement, assertiveness, motivation, persistence, and prosperity. Orange is useful in eliminating procrastination, anxiety, and stress. It is also helpful when trying to divine solutions or new ways of accomplishing your goals.
Yellow corresponds to the Solar Plexus Chakra, the Sun and Sun God(s), joy, cheerfulness, intellect, hope, direction, personal power, clear thinking, concentration, fruitfulness, and communication. It can also correspond to fear and treachery (this can be useful for banishing them). This is a case where the shade of color can make a big difference: Bright yellows tend to carry the positive aspects, while pale or muddy yellows tend to carry the negative.
Green corresponds to the Heart Chakra, the Earth Goddess, the Element Earth, the Green Man (or Horned God), nature, wealth, abundance, longevity, and healing. Dirty or muddy green corresponds to envy, hate, and sickness (a "sickly green", so to speak). When representing with the Earth Goddess, green will almost always appear along with blue. Green is especially useful in color magic spells for healing and for wealth drawing.
Blue corresponds to the Throat Chakra, the Element Water, communication, creativity, integrity, calm, truth, loyalty, justice, leadership and clear thinking. It is used to represent the Earth Goddess when paired with green (the green land and blue seas).
Indigo corresponds to the Brow (or Pineal, or Third Eye) Chakra, idealism, justice, wisdom, inspiration, intuition, spirituality, psychic powers, and the understanding of things. It can also be used in color magic to help reduce phobias and stress.
Violet (or Purple) corresponds to The Crown Chakra, inspiration, spirituality, the sacred, selflessness, tolerantence, intuition, imagination, royalty, wealth, inner peace, security, protection, creativity, freedom, and personal responsibility. It is most often used in spells for protection and psycic ability.
Brown corresponds to grounding, good health, hard work, stability, reward from effort, and earth. Like white, it has the power to enhance other colors in color magic.
Gold corresponds to the Sun, masculine energy, success, money, abundance, power, positivity, confidence, self-motivation, self-discipline, generosity, enlightenment and manifestation. The color is very useful is spells for success, wealth, and self-confidence. Note that Fool's Gold, or Iron Pyrite, has this power (despite of the negativity of the name) and is frequently used for drawing wealth.
Silver corresponds to the Moon, feminine energy, balance, harmony, change, learning, introspection, confidence, wealth, secrets, hidden desires and intuition. It is very useful in divination and meditation. It is also useful for tapping into and increasing your psychic power and/or intuition. On occasion, silver is used for money drawing spells.
Grey corresponds to morning, sorrow, humility, doubt and uncertainty. It would generally not be used in ritual except during funerary rites.The Urban Pagan › Using Magic › Color Magic