The North Node of the Moon is called RAHU in Vedic astrology and the South Node is called KETU. They are called dark or shadow planets, because of the Nodes' association with the phenomena of eclipses.

They have no sign ruler ships, although they are said to favor Mercury and Jupiter's signs according to some authorities, while others claim that Rahu favors the sign of Aquarius and Ketu the sign of Scorpio. Rahu, the North Node of the Moon means to conceal, engulf or hide in Sanskrit.

This Graha is associated with the world of material manifestation and worldly desire. Rahu is associated with the spiritual process of involution, or the engrossing of spirit in materialization. Rahu is a karaka, or indicator, of worldly desire, fame, greed, high intelligence, manipulation, obsessive behavior, foreigners, mass disease, dementia and inertia. The nature of this Graha is Vata, or Airy.
The hessonite is the gemstone of the planet Rahu and helps to overcome problems related to this planet.

A good-quality gomed gemstone of Rahu, is one that reflects the color of the urine of a cow, that is, having a nice honey color. It is a silicate of zirconium and is commonly found in igneous rocks but is fairly rare as a gemstone. Zircon has a considerable range of colors and is found in red, blue, green, yellow, orange, and brown shades. Blue and green hessonite or the white colorless variety of hessonite are not associated with Rahu.

A pure and transparent hessonite having a delicate hue, brilliance, luster, and uniform color neutralizes the evil effects of Rahu, and if Rahu is well posited it gives beneficial results during its major period and subperiods, removes fear, creates clarity of mind, and helps spiritual growth.

Some aspects of the Rituals for Wearing a Hessonite
The weight should not be less than 4 rattikas. The hessonite should be set in a ring or a pendant made of ashta dhatu. The mounting should have an open back to allow the gemstone to touch the skin. The best time to wear a hessonite is two hours after sunset.

Some aspects of the Medicinal Utility of Hessonite
Hessonite pishthi or oxide gives luster to the skin, improves the faculty of reasoning and thinking, gives strength to dhatus (body and semen), and gives longevity, among others. It also cures disorders created by Rahu.