Board Thread:Suggestions Forum/@comment-24.229.47.101-20150131212241/@comment-25672535-20150216184152

Shydes528 wrote: The Eregion elven smiths had the knowledge to forge Rings of Power, taught to them by Sauron. But only Durin's Folk and the other Dwarven Kingdoms, as well as the Elves they chose to share that knowledge with knew how to make Mithril into a workable metal.

The Erigeron smiths taught sauron and they shared their knowledge together to each become better, however Gandalf says in the fellowship of the ring book that elves could smith it to.