Pearls are less durable than most gems. The Pearl is a 3 on the Moh's Scale of Hardness. Pearls may be used in rings, pendants and earrings. They are sensitive to acids, dryness, and humidity. If you wear cosmetics and/or perfume, put these on before putting on your pearl jewelery. When taking off your pearls, wipe them with a dry, lint-free cloth. If needed, clean your pearls with warm soapy water being very careful to avoid wetting the drill hole, as the pearl may become thus discoloured. Dry your pearls flat on an absorbent, soft (preferably lint-free) towel. Always store your pearl necklaces flat as the silk will stretch if the strand is hung. Store pearls separately from other jewelery, as they are easily scratched. Store pearls in a dry environment. Avoid using plastic bags as condensation build up will and cause damage to your pearls.