The ring was a gold band set with Alcamîrër (Q."Glorious Jewels") and was forged in the Second Age by the Elven smiths of Ost-in-Edhil. A powerful talisman made in the later days of the settlement, its maker suspected that there was a hand of Evil at work among the Jewelsmiths and sought to protect all good things against him.
The ring dispelled, repelled, and detected evil. It also alerted the wearer if there was danger nearby and could perceive power.