This is a question I get asked a lot so I thought I would write this blog post for all to see. The following is based on my own opinion and experience but there are many different views on the subject but I feel in time you will find your own best way of caring for your crystals.
Crystals are natural, so I believe in cleaning them in the most natural way as possible. If you are lucky enough to live near a natural spring, then all you need to do is give them a gentle rub with your fingers while holding them in the flowing water of the spring, taking care of course not to drop them in and losing them. If like myself you are not that fortunate to live near a natural spring, then a compromise is to use bottled spring water, please read the label as some of these so called natural spring waters are not that natural. Under no circumstances use flavoured bottled water! If bottled water is not for you then you could use tap water, but remember, tap water is treated to make it safe for us to drink, so it is not that pure.
From time to time you will need to re-energise, to as some people call it charge your crystals especially if used on people in a crystal layout for healing and chakra balancing. Some people say you should never mix or place different crystals together, but this is just not true. In fact placing your different crystals next to a largish piece of natural rough clear Quartz is the most effective way of re-energising the crystals. Doing this in a place of direct sunlight is even better as there is a lot of energy from the sun the crystals can soak up. The same principle can be used for the Moonstones using the energy of the full moon instead of the sun.
Another way is to dig a small hole in the ground and place the crystals in there and cover them with soil and leave them there for a few days to soak up the energy from the earth. Personally I don't think this is a good or practical way, as once you have charged them you will have to clean them before using them in a healing crystal layout, which in turn will let them lose some of the energy they have just gained.
Keep it natural as possible while cleaning and energising your crystals.there are no crystals that can't be charged by a piece of natural rough clear Quartz. Don't worry about placing two different crystals together when re-energising, the only time this could have an adverse effect is during a healing layout as some crystals work in different ways. Finally, love your crystals and they will love you back.