Crystal cave is the best, because the crystal itself is polished by the crystal in the crystal cave. The green ghost itself has the meaning of making money, while the crystal cave has the meaning of gathering money. The crystal cave has a strong magnetic field and is the best. If the landlord wants the simplest one, wash it with clear water and dry it naturally in the shade. According to my experience, it's not so magical, but it's better to use a crystal hole. Everything else you say is nonsense. Crystals should be less exposed to chemicals. Like soap, washing powder, etc. It's best not to bring it when doing housework. Because it will darken the surface luster of the crystal.