Rigdzin Jigme Lingpa (1729–1798) was one of the most important tertöns of Tibet. He was the promulgator of the Longchen Nyingthik, the Heart Essence teachings of Longchenpa, from whom, according to tradition, he received a vision in which the teachings were revealed. The Longchen Nyingthik eventually became the most famous and widely practiced cycle of Dzogchen teachings. Namkha'i and Shane (1999: p. 135) affirm that Jigme Lingpa wrote a treatise on the spiritual and medicinal usage of crystals and gems of principal importance.