In Vedic astrology, the south lunar node, called Ketu, is one of the two shadow planets, the other being Rahu, the north lunar node. Ketu is not a physical body but a mathematical point at which the moon's orbit crosses the ecliptic descending. The gemstone traditionally prescribed for Ketu is cat's eye chrysoberyl, known in Sanskrit as lehsunia or vaidurya.

The gem and its rationale

Cat's eye chrysoberyl is a beryllium aluminium oxide that, when cut as a cabochon and oriented to the parallel rutile or other inclusions within the crystal, displays a sharp band of light called chatoyancy across the dome. The Vedic tradition associates this single eye-like band with Ketu's nature as a mysterious, hidden, partly disembodied force. The recommended stones are natural untreated cat's eye chrysoberyl of distinct chatoyancy, ideally with a milk-and-honey colour pattern in which one half of the cabochon appears milky and the other half a richer body colour when light grazes the surface.

Practical specifications

Traditional jyotish prescriptions specify weight, setting metal, and finger of wear, with cat's eye chrysoberyl typically set in silver and worn on the middle finger of the right hand on a Tuesday at a prescribed lunar phase. Stone weights commonly recommended fall between three and seven carats, with larger weights for stronger remediation. Buyers commissioning jyotish gems should request laboratory documentation confirming species, untreated status, and absence of synthetic or imitation material; cat's eye chrysoberyl is widely imitated by cat's eye quartz, fibreglass, and synthetic alternatives, none of which carry the traditional astrological standing.

Trade context

The jyotish market is significant in India, Sri Lanka, and the South and Southeast Asian diaspora. Major suppliers operate in Jaipur, Sri Lanka, and Mumbai. Reputable laboratories such as the Gem Testing Laboratory in Jaipur and Gübelin issue reports that meet jyotish purchasers' due-diligence requirements. The gem itself is traded entirely on its merits as a natural cat's eye chrysoberyl; the astrological use is layered onto, rather than substituted for, the standard gemmological criteria.