Of all the powers conferred by the One Ring, perhaps the most idiosyncratic and random is its ability to turn the wearer invisible. Why does it do this in the first place? Well, the real answer is because Tolkien wrote it as a ring of invisibility well before he knew what it was or what significance it held to his story and his world.
But since the Ring is, among other things, a ring of invisibility, it’s reasonable to ask questions about its properties and limitations.
In The Hobbit, it seems that the spiders can see Sting even while Bilbo himself is invisible.
The spiders saw the sword, though I don’t suppose they knew what it was, and at once the whole lot of them came hurrying after the hobbit along the ground and the branches.J.R.R. Tolkien, The Hobbit, “Flies and Spiders”
This circumstance does suggest some further questions. For instance, what about a bow and arrows? If the bow were stored in a harness on the person’s back, would it still be visible? Would the arrows sticking out of the quiver be visible, or only when drawn from the quiver? Tragically, these questions are not, to my knowledge, ever addressed.
In The Return of the Shadow, which documents the various drafts and revisions made to the Fellowship of the Ring manuscript during its writing, Tolkien has Frodo playing a joke on Farmer Maggot using the Ring:
‘Well then, one more drink!’ said the farmer, and his wife poured out some beer. ‘Here’s your health and good luck!’ he said, reaching for his mug. But at that moment the mug left the table, rose, tilted in the air, and then returned empty to its place.J.R.R. Tolkien and Christopher Tolkien, The Return of the Shadow, “A Shortcut to Mushrooms”
I feel like the two quotes above make it abundantly clear that Tolkien intended the effect of the Ring to not include items held by the wearer, although it clearly does include items worn by the wearer. An even earlier revision had Frodo instead stealing and wearing a hat (which remained visible) while he walked out the door. Apparently Christopher asked “if Bilbo’s clothes were invisible, why did the hat remain visible?” and Tolkien, having no answer, changed the story into one about drinking to avoid that conundrum.
Buuuut…there’s one more interesting quote that adds another wrinkle to the puzzle:
Isildur turned west, and drawing up the Ring that hung in a wallet from a fine chain about his neck, he set it upon his finger with a cry of pain, and was never seen again by any eye upon Middle-earth. But the Elendilmir of the West could not be quenched, and suddenly it blazed forth red and wrathful as a burning star.J.R.R. Tolkien, Unfinished Tales, “Disaster of the Gladden Fields”
The Elindilmir was the jewel on Isildur’s crown, which was apparently visible even when Isildur himself was invisible. So the invisibility conferred by the Ring has some very odd properties:
- It turns the wearer invisible, including anything he or she is wearing.
- The wearer still casts a shadow, which can be seen even if the wearer cannot.
- (Some?) light emitted by worn objects can be seen.
- Objects carried in the hand can be seen, even if they were formerly worn.
I…think it best that we not ponder this matter any further. Some parts of the Legendarium are somewhat fragile and can be broken if prodded too hard….