A Silmaril is one of the star-like Elvish jewels made by Fëanor in J.R.R. Tolkien's The Silmarillion.
Fëanor creates three Silmarils during the First Age. They contain the light of the Two Trees of Valinor, Telperion and Laurelin, whose radiance existed before the Sun and Moon. Because of their beauty and sacred light, the jewels become the focus of immense desire.
Morgoth steals the Silmarils after destroying the Two Trees and sets them in his crown. Fëanor and his sons swear a terrible oath to recover them, beginning a long chain of wars, betrayals, and tragedies known as the War of the Jewels.
The name can refer to one jewel or to the group collectively as the Silmarils. They are not the Elfstone associated with Aragorn and Arwen, nor are they Palantíri, which are seeing-stones. Their story gives The Silmarillion much of its central historical and moral structure.