Kundalini Yoga Mudra's: Gyan-mudra
To form gyan mudra put the tip of the thumb together with the tip of the index finger (1). This stimulates your knowledge and ability. The energy of the index finger is often symbolized by Jupiter, the planet representing expansion. This mudra is the one most commonly used. It gives you receptivity and calmness. In the practice of powerful pranayams or exercises the "active"form of the mudra is often used (2). In this case you bend the index finger under the thumb so the fingernail is on the second joint of the thumb.