[Nilpaurion Felagund]

Let me say: I think they couldn't have.

Gwaith-i-Mirdain was the only one (I think) whom Sauron instructed in the forging of the Great Rings. Then he ransacked the place. Even if written records of the process was kept, I don't think it would have survived the Sack of Eregion.

And then there's the thought that the Gwaith might be all dead. So the only two ways of that information surviving (archaelogical records and word-of-mouth) might have been gone.