The Silmarillion » Elves » Noldor (House of Fingolfin)
Idril “Sparkling Brilliance”
called Celebrindal, Silver-foot, the golden-haired daughter (and only child) of Turgon the King of Gondolin and Elenwë. Maeglin, son of Aredhel, loved her but she did not love him due to his dark character and because they were too closely related (they were cousins, Aredhel was Turgon’s sister). His love, however, turned to darkness in his heart. Idril married the mortal man Tuor (the son of Huor and Rían) and their son was Eärendil Half-elven (Elrond’s father).
Idril made a secret passage leading out of Gondolin because she feared an attack from Morgoth. Indeed, Morgoth attacked Gondolin and Tuor was going to lead Idril out of the city when Maeglin siezed her. Tuor fought and cast Maeglin down into the rocky slopes below. Tuor and Idril helped their people escape through the passage she made. They passed over the mountains to Nan-tathren and went southwards down the river to the sea and dwelt by the mouth of the Sirion, joined by Elwing‘s people. After a while, Tuor built a ship called Eärrámë (Sea-Wing) and sailed with Idril into the West. Tuor, alone of mortal men, went with the Noldor to Valinor.
Idril also owned the original Elessar, the Elfstone necklace that was made by the Elven-smith Enerdhil. It was green as leaves and it was said that all “those who looked through this stone saw things that were withered or burned healed again and the hands of those that held it brought to all that they touched healing from hurt”. Before Idril set sail with Tuor in 560 First Age, she gave this jewel to her son Eärendil to heal all the hurts of Middle-earth. However, once Eärendil sailed into the heavens, the Elessar was lost. A second Elessar was made for Galadriel in the Second Age. For the story of Idril’s son Eärendil, see Elwing.