Fëanor created three Silmarils in J.R.R. Tolkien’s mythology.
The Silmarils were three jewels made by Fëanor, an immensely gifted Elf of the Noldor. They contained the light of the Two Trees of Valinor, Laurelin and Telperion, whose radiance existed before the Sun and Moon in Tolkien’s mythology.
Their theft by the dark lord Morgoth drives much of the history told in The Silmarillion. Fëanor and his sons swore an oath to recover the jewels, and that oath led to rebellion, wars, and tragedy among the Elves. The Silmarils were not ordinary precious stones: they were sacred objects tied to the lost light of Valinor.
The number is sometimes confused with other important Tolkien numbers, such as the seven Rings made for the Dwarf-lords or the nine Rings given to Men. Those belong to a different part of the legendarium.