In J.R.R. Tolkien’s mythology, what are the Silmarils?

In J.R.R. Tolkien’s mythology, the Silmarils are three jewels created by Fëanor.

Fëanor, the greatest craftsman among the Noldor Elves, made the jewels during the First Age. They contained the mingled light of the Two Trees of Valinor, Laurelin and Telperion, before those trees were destroyed. Their beauty and sacred light made them the most prized objects in the legendarium.

The jewels became the focus of a devastating oath and a long series of conflicts. Morgoth stole them and set them in his crown, leading Fëanor and his sons to pursue them. Their history is central to The Silmarillion and helps explain the exile of the Noldor, the wars of Beleriand, and many later tragedies. The Silmarils are distinct from the One Ring, which belongs primarily to the later history of the Second and Third Ages.