Yeouiju
The yeouiju is the wish-granting jewel of Korean lore, the glowing orb that a serpent, imugi, must grasp to climb into full dragonhood, and that grants any wish to its holder. In the tales the imugi, a hornless dragon, waits for the jewel to fall from the sky or to be revealed by a righteous person, and the story of the imugi that lost the jewel at the waterfall is among the most famous Korean dragon tales. The yeouiju is also described as the possession of the dragon kings of the sea and of the mountain spirits, and its power is sometimes linked to the moon, whose light it is said to drink. I