Rings of Power talk!

[jallanite]

Of the rings Sauron created, Tolkien writes in Letter 131 to Milton Waldman (emphasis mine):

And finally they [the Rings of Power created in part by Sauron] had other powers, more directly derived from Sauron (‘the Necromancer’: so he is called as he casts a fleeting shadow and presage on the pages of The Hobbit): such as rendering invisible the material body, and to make things of the invisible world visible.

The Elves of Eregion made Three supremely beautiful and powerful rings, almost solely of their own imagination, and directed to the preservation of beauty: they did not confer invisibility.

So the rings worn by Cirdan and Gandalf, by Elrond, and by Galadrial “did not confer invisibility.” Presumably all of the other Rings of Power did or could confer invisibility.

But in The Lord of the Rings, Appendix A, III DURIN’S FOLK, Tolkien writes of the dwarves:

But they were made of a kind to resist most steadfastly any domination. Though they could be slain or broken, they could not be reduced to shadows or enslaved to another will; and for the same reason their lives were not affected by the Ring, to live either longer or shorter because of it.

This implies that dwarves could not be rendered invisible merely by the wearing of one of the Seven Rings. (If they had been rendered invisible, one would have suspected that the dwarves would have known of this power and would have suspected when they learned of Bilbo’s ring that it might be one of the lost dwarf rings.) Possibly a dwarf wearing a Ring could become invisible by so willing.