In J.R.R. Tolkien's mythology, what are the jewels created by Fëanor called?

In J.R.R. Tolkien's mythology, the jewels created by Fëanor are called the Silmarils.

The Silmarils are three extraordinary jewels made by Fëanor, the greatest craftsman among the Ñoldorin Elves. They contain the light of the Two Trees of Valinor, Telperion and Laurelin, which existed before the Sun and Moon. Because of that light, the jewels are central to the history of the First Age.

Morgoth steals the Silmarils after destroying the Two Trees, and Fëanor swears an oath to recover them. The oath drives Fëanor and his sons into rebellion and leads to long wars, betrayal, and tragedy. Much of The Silmarillion follows the consequences of the jewels' theft and the attempts to reclaim them.

The Silmarils are distinct from the Palantíri, which are seeing-stones, and from the Rings of Power, which are forged objects of a later age. The Arkenstone is a precious jewel associated with Erebor in The Hobbit, but it is not one of the Silmarils.