While Celebrimbor alone forges the three sets of the Eregion, these are forged from Darklord Saurons hand, bound together into a single Ring. While Celebrimbor created the Set of Three himself, The Dark Lord Sauron left for Mordor and forged The One Ring, a Master Ring that would rule over all others, in the flames of Mount Doom. While Sauron helped in creating the Seven Rings given to the Dwarves, and Nine given to Men, Sauron also forged Rings, alone, on Mount Doom.

Who forged the Rings in Lord of the Rings?

Although the other Rings of Power were made by the Elven Smiths of the Eregion Sphere, Sauron forged the One Ring. The Ring, which was made for an Elvish King, was completed around 90 years later, while Sauron forged the One Ring 10 years later, about the year 1600 A.D. Much of Saurons strength and will was transferred to the One; for the Elven rings were very powerful, and what was to rule over them had to be something with more than enough strength; and Sauron forged it on the mountain of fire, in the land of the shadows. Now, the Elves made many rings; but secretly Sauron made one, and the Elves power was bound up with it, to obey him entirely, and last only as long as it too should endure.

Celebrimbor made the Nine by himself, making sure that Sauron had no part in their making, and Sauron made the One, the strongest ring, in secret. Although he had no hand in crafting, Celebrimbor–a master of crafts–made the titular Ring of Power using techniques shared by Sauron. Sauron helped the Elves smith the sixteen Rings, and Celebrimbor made three, which were then given to Galadriel, Gil-galad, and Cirdan. Disguising Sauron to prevent the Elves from recognising him as what he really was, Sauron convinced the Elvensmiths, led by Celebrimbor, to forge the rings under his direction.

Adopting a fake name, Annatar, or Lord of Gifts, Sauron taught the Elven-smiths of Eregion how to infuse their titular Power Rings with strength, and assisted them in creating the first 16 rings, called the Great 16

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