Enerdhil

From Tolkien Gateway

Enerdhil was a legendary, and quite possibly mythical, smith of Gondolin. According to one account, it was Enerdhil who made the original Elessar, an astonishing green gem through which marred and broken things could be seen as though whole and healed again. This Elessar was given as a gift to Idril Celebrindal, and given by her to her son Eärendil, who bore it on his voyages across the Great Sea.

Other versions of the legendarium

However, other more recent accounts name Celebrimbor as the maker of Eärendil's Elessar, as well as the later version borne by Aragorn. Even if this is true, Enerdhil the smith of Gondolin may still have existed, though it is equally possible that he was merely a passing, insubstantial character that Tolkien meant to discard entirely.

The fact that there are two possible Elessars, makes Enerdhil fit into the mythos, as the first could be made by him, and the second by Celebrimbor. But not even this have been resolved clearly.