Charging a crystal or stone is to help it get its energy back to its fullest.
First, clear any unwanted or negative energy from the crystal or other stone. Then proceed with the method of charging your crystal that feels best to you. Here are several methods you can use.
With all methods of charging, first set your intention and state silently or aloud that you are doing this to charge your crystal for the best and highest good of all concerned. After your stone is charged, thank the Divine by whatever name you know it for assisting in charging your stone.
Sunlight or Moonlight Method: The sun’s and moon’s rays are very energizing, as well as energetically clearing. You can use this method to both clear and charge your crystals at the same time. Find a safe place and leave your crystal for 24 hours or more (up to a week) in sunlight and/or moonlight. Some crystals colors will fade in Sunlight, so those should be charged only in moonlight. Some stones that will fade in the sun are amethyst, celestite, kunzite, opal and turquoise. If you have any doubts at all, only use moonlight charging. This can also clear the stones of unwanted energies at the same time if you set your intent to do that as well.
Charging Stones: Some stones can be very energizing to other stones. In most cases they can also clear their energy. That makes using charging stones a handy method of charging a crystal. Simply place your crystal needing charging on a cluster or larger piece of a stone that can charge others such as selenite, amethyst cluster, quartz cluster, or carnelian. Leave your crystal there for 24 hours or until it feels like it is at full energy.
Charging Grid: This is a variation on using charging stones. Take a group of quartz crystals (4 to 8 or more) and point them inward in a circle. Place the crystal or stone you want charged in the center of the circle and leave it there to charge for 24 hours or more.
Plant Method: Place your crystal among the leaves of a growing, healthy plant for 24 hours or more to charge it. This is said to bring growth energies to the charged crystal.
Burial: This method is good for grounding stones in particular, such as most any black stone, smoky quartz, red jasper and others. Bury the stone in the ground for a week or more to charge it. This can also clear unwanted energies at the same time. Be sure when you bury your stone that you mark the area so you know where to find it when the week is up.
Whichever method you choose, the exact length of time needed for charging varies according to the state of the crystal or stone to begin with. Trust your intuition and higher self to lead you to the best methods and lengths of time for you and the stone.