According to the text of sacred texts, Vaidoorya or Cat’s eye is the gemstone of Ketu. This gem, with its band of reflected light across the middle looks like the eyes of a cat. This unusual phenomena is called as Chatoyancy.
Ketu is unbiased, hybrid, inactive, disfigured and troublemaking. He creates disturbances in the physical bodies of its natives, causing them to lose interest in life. Ketu is shown with a headless torso with a fish body, called the dragon’s tail. He holds a flag of self glory in his hand. Ketu is less destructive than Rahu and leads its natives toward salvation from the bondage of life and death making them passive.
Ketu is a headless half-planet, shadowy as Rahu and malefic, though not as malefic as Rahu – and therefore he is known as the redeemer of souls and therefore a moksha-karaka. It bestows spirituality, somberness and detachment from worldly desires and ambitions. Ketu also bestows wisdom, powers of discrimination and gyana – spiritual knowledge and knowledge of self. It gives psychic abilities to its natives and makes them masters of the healing arts, natural healing, healing herbs, spices, foods, tantric healing, healing of persons possessed by evil spirits, ghosts and astral forces. Ketu natives also have the ability to merge among commoners.