I think the most powerful is to use the moon, preferably when it?s full. I would suggest doing this for several nights so start one night before the full moon and let the crystal absorb the energy through one night after the full moon. You simply place your stone outside under the moonlight and let the moon do its work.? If it feels appropriate to you, you might say a few words to the moon and the Goddess, asking them to bless the stone and charge it with their energies.? Do what feels right to you and what feels most natural. After the third night your stone is ready for you to use in your daily practice as you see fit. On a day when the sun and moon are in earth signs, charge your pentagram by anointing it with essential oil of mint, pine, patchouli, amber, or basil. Place it in a waterproof container, and bury it beneath a tree for a week. At the end of the week, dig it up and tell it how you want it to work with you. Either wear your pentagram or wrap it in green silk and store it in a safe place until you're ready to use it.