Use natureal sea salt. You can buy this just about any where, the grocery store, health food stores or even wal-mart.
Use a glass or wooden bowl. Pour the sea salt in the bottom of the bowl so that it is covering the bottom. Place your crystals.gemstones in the bowl, make sure they are not piled on top of each other. Then pour the sea salt over the crystals/gemstones until they are covered. Place the bowl in a dark quiet place for about 3 to 4 hours. When the time is up take your crystals/gemstones out and wipe them with a clean soft cloth to remove the sea salt. Remember to discard the sea salt after, for you do not what to reuse it, for it has the negative energies in it.
For this you do not want to use the crystals/gemstones for example opal, lapis, coral, pearl or any cyrstal or gemstone that are softm delicate or porous.
Use a glass or wodden bowl. Use warm purified or spring water (no tap water unless you have a filter on it). Let the sea salt dissolve in the water. Place the crystals in the bowl, you want to make sure that the salt water is covering the to of the cyrstals/gemstones. Let them soak in the salt water for about 3 to 4 hours. Take them out and rinse them off with cool water and then wipe then off with a soft clean cloth.
You can do this if you have a stream or river in your back yard. Place the crystals in a mesh bag or cheese cloth. Tie it up and place it in the water for about 3 to 4 hours. Take them out and dry them off.
Ths cleanses and re-energized you crystals/gemstones.