One of Selenite's properties is that it amplifies and purifies the energy of other crystals. Selenite does not need to be cleansed, it naturally transmutes negative energy. This is the reason why it is so beneficial for cleansing and charging your enerygy and your crystals energy.
 
We recommend keeping the crystals you use daily in your Selenite bowl for continuous cleansing
Leave them there to charge for a minimum of 6 hours.