There are a few different methods.
You can wash it in salt water (some crystals don't like to be immersed in water so check who you got them from), you can let clean filtered water run over it, you can leave it in the sunshine and or moonlight (again sunlight can cause some crystals like ameythyst and citrine to fade if left for a long time) to clean them. You can also smudge them with smoke as well. The most important thing I feel is the intent, that from this 'ritual' you are removing any negative energy and clensing it.

I do the following. I hold the peice in my hand, imagine the golden white light coming down from above and surrounding me, I imagine it going into the peice and say I ask that all negative energy and lower energy attached to this piece be removed and sent to the ether where it can hurt nothing and no-one, I ask that it be filled with golden white light, I asked that it be clensed... all the time imagining it filled with white light so that it glows.


I was also thinking cause circumstances are that you are living with them that when you are feeling more protected that you could send them unconditional love, not from you but from source, god, gaia or whatever you believe in. So hopefuly they won't feel the need to suck from you as much