Among precious stones, jade tastes sweet and belongs to Yang, while gold tastes pungent and belongs to Yang. For example, Hetian jade with tremolite as the main mineral has an aphrodisiac effect; Bai Shiying, the main mineral of crystal, has a remarkable effect on male impotence, nourishing yin and strengthening yang. Black agate and black time also have a good effect on treating kidney and nourishing kidney yang.
Emerald: Since it was discovered by human beings, it has been regarded as a magical power to ward off evil spirits. People regard emeralds as amulets, evil spirits or religious ornaments, and believe that wearing emeralds can resist the invasion of poisonous snakes and beasts.