Cleansing your crystals are so important because they absorb energy - negative and positive - from everything and everyone around them. Cleansing should be done after every use. There are various ways to do this.
How To Cleanse Your Crystals
~Water: Just like a shower meditation, sea or salt water can wash away the energy that has been absorbed. [Note: Amber, Calcite, Opal, Kunzite, Kyanite, Lepidolite, Malachite, Moonstone, Selenite, Topaz, and Turquoise should avoid water]
~Sage: Light your sage, cleanse yourself, and then pass your crystal through the smoke to rid it of the energy that has been absorbed.
~Selenite: This crystal has the ability to cleanse and charge your crystals. Place in bowl or wave a selenite wand over your crystals.
~Clear quartz cluster: Place crystals on top of a clear quartz cluster and keep it there overnight.
~Full Moon: The full moon will cleanse your crystal and charge it. Put your crystals outside somewhere safe and leave them out for a few hours or all night.
~Sunlight: The sun will burn off the energy, purify, and recharge your crystal. (Note: Amethyst, Ametrine, Apatite, Aquamarine, Aventurine, Calcite, Celestite, Chrysoprase, Citrine, Fluorite, Kunzite, Rose Quartz, Sapphire, and Smoky Quartz should avoid sunlight as it will make them fade)
~Visualization: Visualize your crystal surrounded by light with the light taking away the energy that it has absorbed.