Spiritual Cleansing
Spiritualists claim that sea salt water can be used to cleanse crystals of stagnant energy and the daily accumulation of all the negative energy in the world. But they also caution against using sea salt water on soft crystals and stones like opal, jade, and malachite, as undissolved salt could scratch the stones.
Oxalic and Muriatic Acid
Rock hunters may be familiar with oxalic acid and muriatic acid. Both are safe for hard crystals like quartz and amethyst, but should be tested on small samples for softer stones like malachite, lapis and opal to ensure the acid won't dissolve the stone.
Cleaning Jewelry
Many stones and crystals are encased in sterling silver settings, so the silver must be cleaned without damaging the stone. Soaking in household ammonia is safe for hard crystals and diamonds. Softer gems, like emeralds, can be dipped in alcohol and then gently scrubbed with household ammonia.