Andvaranaut

In Norse mythology, Andvaranaut (12th c. Old Norse: ), meaning Andvari's Gem ("Andvari's precious possession"), is a magic ring, initially owned by Andvari, that could help with finding sources of gold.

The mischievous god Loki stole Andvari's treasure and the ring. In revenge, Andvari cursed the ring to bring misfortune and destruction to whoever possessed it. Loki quickly gave the cursed Andvaranaut to Hreidmar, King of the Dwarves, as reparation for having inadvertently killed Hreidmar's son, Ótr. Ótr's brother, Fafnir, then murdered Hreidmar and took the ring, turning into a dragon to guard it. Sigurd (Siegfried) later killed Fafnir and gave Andvaranaut to Brynhildr (Brünnehilde). Queen Grimhild of the Nibelungs then manipulated Sigurd and Brynhildr into marrying her children, bringing Andvaranaut's curse into her family.

Literary references
Richard Wagner used Andvaranaut as inspiration for the title of his musical drama Der Ring des Nibelungen. J.R.R. Tolkien may have been inspired by Andvaranaut when designing the One Ring, both by making the One Ring cursed and by making one of its aspects to allow the wearer to find the other Rings of Power, knowing the location of the wearer of each of the Rings of Power, so that the wearer of the One Ring could control these Ringbearers.