The Enchanted Ring is an Ancient Nordic artifact found in Saarthal during Arniel Gane's expedition.
Acquisition
During the quest Under Saarthal three of these rings are collected in total by the Dragonborn. Optionally, the rings can be returned to Arniel afterwards for a small gold reward.
The rings can be disenchanted at an Arcane Enchanter for the Fortify Health enchantment. Otherwise, they can be kept, sold, or can be worn.