You can see when a crystal needs cleansing–it loses its sparkle, brightness and even color, and may feel sticky in your hand. Dust is drawn to crystals because of their electric properties, adhering to them through an electrostatic charge. This alters their natural healing abilities, reducing the number of photons of light reaching the crystal. Regular cleansing prevents a buildup of dust.
The other reason crystals have to be cleansed is that they pick up energy when we are working with them, either from ourselves or from others. They will even pick up energy from people in a shop and, in fact, may have been handled by any customers before you. There is nothing wrong with these energies–they’re not “good” or “bad”–it’s just that they’re not yours, and it’s your energy the crystal will be working on or with to achieve its healing effects.
Witches Of The Craft® 