When were the Rings of Power forged and by whom?

Answer 1

The Three Rings of Power were made by Celebrimbor, elf lord of the Gwaith-i-Mirdain (Guild of Smiths) in Ost-in-Edhil during the Second Age. Celebrimbor was the son of Curufin and the grandson of Feanor, greatest of all elven and any other smiths. Sauron never touched them or helped in their making, which is why they endured free, even after Sauron reclaimed the 7 given to dwarves and the 9 given to men.

Answer 2

The Rings of Power were forged around the 16th century of the Second Age of Middle-earth. Sauron went to the Elves of Eregion in the fair guise of Annatar and taught them how to make the rings. The Seven and the Nine were made by the Elves with Sauron's assistance. The Three (Vilya, Nenya, Narya) were made only by the elf Celebrimbor, and Sauron had no part in or knowledge of their making. The One Ring was forged by Sauron alone in Mount Doom in Mordor.

Answer 3

There were twenty rings in all. Nineteen were given, and One for the Dark Lord.

Three Rings for the Elven-kings under the sky,

Seven for the Dwarf-lords in their halls of stone,

Nine for Mortal Men doomed to die,

One for the Dark Lord on his dark throne

In the Land of Mordor where the Shadows lie.