Placing crystals in the light of the sun can cleanse them. Check that they won't fade first and take care to ensure the suns rays are not focused in a way that could start a fire
Placing crystals in the moonlight for a few hours can cleanse them. Full moon's are the best times to cleanse crystals and have the added impact of charging your crystals too.
Crystals can be held under running water or immersed in sea or salt water to wash negativity away. Be careful that the crystals do not dissolve in water before using this method as it is not suitable for all types of crystal.
Lighting a Sage Smudge stick and running crystals through the smoke will purify them and cleanse them. Be sure to set your intent whilst cleansing them in this way.
You can pass your crystals through the light from a candle to repurify them and surround them with light.
Cleansing sprays are now readily available that can be used to cleanse your crystal . Alternatively an atomiser of water and essential oils can be used
Certain crystals can cleanse others. Carnelian can cleanse crystals when placed in a bag overnight. Or selenite is great at keeping crystals it is with energetically charged and cleansed.
Return crystals to the ground or place next to plants. Being close to their original source helps to cleanse them and renew their energies.
Use incense to run crystals through the smoke
Imagine the crystal surrounded by intense light which purifies and energises them. This can be an effective method when all others are not available.
Certain sound vibrations run through the crystals cleansing any negative energy. Singing bowls are the most common way to get a great sound energy.
Place your crystals in sea salt overnight. Ensure that you brush off all the salt once you take the crystals back out from the salt as in some cases the salt can damage the crystal structure over a longer course of time.