Brass pendant sculpture in the shape of "Vajra" or "Dorje" symbol of lightning and diamond (small)

Vajra is a Sanskrit term which means both lightning and diamond as well as a symbolic object that represents it in Tibetan Hinduism and Buddhism, especially in tantric rituals.
The Tibetan equivalent is called dorje, which is also a popular name in Tibet, Bhutan and Mongolia (in the form of Дорж Dorj).
In Hindu mythology the vajra, which represents the natural phenomenon of lightning, is challenged as a weapon by Indra, King of the gods, in a similar way to Zeus, the Father of the gods in Greek mythology. Vajra represents indestructibility, and as the most powerful weapon, it has the quality of not being able to be used inappropriately and has the property of always returning to those who wield it.
In Buddhism, vajra as a symbol of the nature of reality, the transformation and use in Buddhism becomes clear with the identification of that nature with the concept of emptiness (Sanskrit: sunyata). The void, the very nature of lighting, is like lightning and indestructible like diamond. This concept takes on a character so central in Buddhist speculation that it gives its name to the third great transformation of Buddhism with the Vajrayana, that is, the Diamond Vehicle after the Hinayana and the Mahayana.