Would Gandalf be invisible if he wore the One Ring?

Question

If Gandalf wears the One Ring, will he be invisible? Or will he master it and be visible?

Maybe I should ask: is there a chance that the "invisibility" effect of the Ring is a side effect of weakness?

Answer 1

Here's an argument for no

I am going to say no because of this passage in the Lord of the Rings

‘A mortal, Frodo, who keeps one of the Great Rings, does not die, but he does not grow or obtain more life, he merely continues, until at last every minute is a weariness. And if he often uses the Ring to make himself invisible, he fades[.]

^{The Lord of the Rings | The Shadow of the Past}

Now Gandalf here is referring to the Great Rings (which we can take to include the 9 and the 7) what this tells me that any of the great rings would make a mortal invisible, not just the One Ring.

As he is saying this Gandalf is wearing one of the Three Rings and is visible. The other bearers of the great rings are elves and also are not invisible.

On the question of the great rings

The evidence is that all the great rings make you invisible (they are all dangerous to mortals).

• The nine make men disappear, so much so that they fade and become wraiths under the dominion of The One. Although it is said in the Silmarillion that

  They could walk, if they would, unseen by all eyes in this world beneath the sun, and they could see things in worlds invisible to mortal men;

  ^{The Silmarillion | Of the Rings of Power and the Third Age}

  The keyword being could, can we take that to mean once they had gained mastery of the ring they could be visible while wearing it?

• The seven did not make the dwarves invisible, nor did it give the wielder of The One dominion over them, this is because of the way Aüle created them.

  The Dwarves indeed proved tough and hard to tame; they ill endure the domination of others, and the thoughts of their hearts are hard to fathom, nor can they be turned to shadows. They used their rings only for the getting of wealth; but wrath and an overmastering greed of gold were kindled in their hearts, of which evil enough after came to the profit of Sauron.

  ^{The Silmarillion | Of the Rings of Power and the Third Age}

• When Frodo wears the one, he sees Glorfindel's true form as it is "on the other side".

  I think that's the key, the immortal spirit doesn't because by their very nature they are already part of the spirit world and cannot be unnaturally drawn to it like a mortal.

Answer 2

Bearing in mind that there is no canon answer, what follows is purely my speculation.

He would probably turn invisible

The invisibility effect of the One Ring is not a matter of mastery, but of the nature of the wearer¹. Sauron doesn't become invisible because, as a Maia (angelic spirit), he principally exists in the Unseen World.

Now, Gandalf is also a Maia, sort of; his soul is that of an angelic spirit, but his body is completely real, and physically no different from any other incarnate creature.

This is where we distinguish between Gandalf and Sauron: although Sauron also has physical form, his body is a manifestation created by him; in Ainulindale, we learn something of this power:

[T]heir shape comes of their knowledge of the visible World, rather than of the World itself; and they need it not, save only as we use raiment, and yet we may be naked and suffer no loss of our being.

^{_{The Silmarillion I Ainulindale}}

Although this passage is technically about the Valar, it applies in equal measure to the Maiar.

Gandalf's form, in contrast, is not created by him; he is well and truly "embodied", and tethered to his physical form in a way that's never fully explained; per Unfinished tales:

For with the consent of Eru [the Valar] sent members of their own high order, but clad in bodies as of Men, real and not feigned, but subject to the fears and pains and weariness of earth, able to hunger and thirst and be slain; though because of their noble spirits they did not die, and aged only by the cares and labours of many long years.

^{_{Unfinished Tales Part IV Chapter 2: "The Istari"}}

This would seem to imply that Gandalf would be affected by the Ring in much the same way as any other incarnate being: by turning invisible.

---

¹ As with every other sweeping generalization about Middle-earth, this statement is complicated by the existence of Tom Bombadil. Bombadil's nature is a hotly-debated mess, and I'm not going to try and resolve it here. Let's just note that this is a slight oversimplification, and quietly move on with our lives

Answer 3

Actually, based on @JasonBaker's answer, I'd say

Gandalf would not disappear, but have some kind of Maia-projection appearance.

So, yeah, the real body would disappear, but Gandalf is still a Maia, and he should still project something into the real world. It's perhaps a bit sacrilegious of me to reference the films, but I'm reminded of that moment Galadriel imagined herself wearing the one ring. Her image was no longer just her body - something else was being projected. So take your photoshop, cut her body out of there, and you've still got something visible.