Silmarils

The three great jewels made by Fëanor in Valinor, in which he locked the Llight of the Two Trees, Laurelin and Telperion, before their destruction. Melkor stole the jewels from Fëanor's stronghold at Formenos, slaying his father Finwë, and fled with them back to his fortress of Angband in the north of Middle-earth.

Fëanor swore an oath to recover the Silmarils, and many of the Noldor followed him into exile in pursuit of the jewels. So began their hopeless war against the forces of Morgoth, of which the Quenta Silmarillion (the 'History of the Silmarils') tells the story. Despite their efforts, one Silmaril alone was recovered from Morgoth's Iron Crown, not by the Noldor, but by Beren and Lúthien. This Jewel was borne by Eärendil when he sailed into the West to seek the aid of the Valar.

By virtue of the Silmaril, it is said, Eärendil reached Aman and was heard by the Valar, who sent a mighty force into Middle-earth. Morgoth was utterly defeated, and the Silmarils recovered. Maedhros and Maglor, the only two of Fëanor's seven sons to survive until that War of Wrath, stole the jewels from the camp of the Valar. Their evil deeds in pursuance of the jewels, however, drove them to madness; Maedhros cast himself into a fiery chasm with one of the Silmarils, and Maglor threw the other into the depths of the sea. So only one Silmaril remains visible in the world, bound to Eärendil's brow as he sails the heavens: the Morning and Evening Star.