Black is the absence of color. It represents the unconscious and mystery. Its visualization can help promote deep meditation. Black also stands for evil (eg black magic). In the aura it signifies some kind of blockage or something being hidden.
Pink represents unconditional love, love requiring nothing in return. It is also the color of friendship and conviviality. In the aura it signifies balance between the spiritual and the material.
Blue is the color of spirituality, intuition, inspiration and inner peace. It is also associated with sadness and depression (the "blues"). In healing blue is used for cooling and calming, both physically and mentally. In the aura blue indicates serenity, contentment and spiritual development.
Red symbolizes energy, passion, strength, courage, physical activity, creativity, warmth, and security. It is also associated with aggression. In healing, use red to bring warmth and burn out disease. Red is a powerful color and should be used in moderation. In the aura red signifies materialism, materialistic ambition, a focus on sensual pleasures and a quick temper.
silver/titanium are gray this is a cold colour with no warmth or healing or spiritual powers. this is an invisible colour.