Place crystals somewhere that they will be fully exposed to the energizing rays of the sun and moon. Even if the day is cloudy or you cannot see the moon, their rays will energize the stones as long as they are directly exposed to these elements of nature. 

They will normally be cleansed within 24 hours of exposure. However, stones such as black tourmaline which are being used to deflect negative energies or help release negative energies in your physical and energetic bodies, may require up to 48 hours to become fully cleansed and regenerated. 

Stones such as amethyst will fade in the sun so you will have to use another method for cleansing and regenerating these gemstones. 

Place your crystals, directly into the Earth or you can place crystals into a cloth covering, preferably a natural fabric such as cotton. Leave the crystal buried for at least 24 hours to ensure that they become fully re-energized.  

If possible, find a spot where the soil is not being spread with chemicals through fertilizers or pesticides. This cleanses all negative energies and re-energizes the stones.

My favourite!! Use white sage and begin to burn it until a good strong smoke is coming from your sage. 

Hold the crystal in this smoke for at least one minute and preferably 3 or 4 minutes. This clears all negative energies that have become attached to this stone but does not energize the gem or crystal.  

To re-energize the stone, place it in a window so it can be exposed to the rays of the sun and moon.

You can place the crystals, on another crystal, preferably a large quartz cluster. This will clear negative energies and will also re-energize your crystals. 

Make sure you also cleanse and re-energize the large quartz crystal cluster regularly to ensure it retains its cleansing and re-energizing powers.

If you are lucky enough to live where you have access to beautiful clear running water from a creek or river that you know is not polluted, place your crystals in a small container, and let the water run over them, preferably for at least 2 hours. 

This will cleanse and re-energize your crystals. Please do not use tap water, since it is full of chemicals.  Be careful though because certain stones will actually dissolve in water, e.g. Red Selenite.