Is the One Ring’s appearance described in the books?

Question

Is its appearance, shape, etc. actually described within the canon (besides that it is a gem-less ring)? I think everyone has the One Ring from the films in mind, where it is depicted as a golden ring, with a rather flat profile and a width of approximately 5mm.

I think it's not said anywhere in canon what material the ring was forged from, but is there a mention of its color? I don't think there is any within The Hobbit or The Lord of the Rings, but I'm not sure, and I have not read the Silmarillion and the other books, yet.

Answer 1

The One Ring is a plain, gold-coloured and unadorned ring. Here's the description from Shadow of the Past:

Gandalf held it up. It looked to be made of pure and solid gold. 'Can you see any markings on it?' he asked.
'No,' said Frodo. 'There are none. It is quite plain, and it never shows a scratch or sign of wear.'

And here it's described again, this time in Saruman's words, from the Council of Elrond:

"The Nine, the Seven, and the Three," he said, "had each their proper gem. Not so the One. It was round and unadorned, as it were one of the lesser rings; but its maker set marks upon it that the skilled, maybe, could still see and read."

And here's Isildur's description of it, again from the Council of Elrond:

Yet even as I write it is cooled, and it seemeth to shrink, though it loseth neither its beauty nor its shape. Already the writing upon it, which at first was as clear as red flame, fadeth and is now only barely to be read. It is fashioned in an elven-script of Eregion, for they have no letters in Mordor for such subtle work; but the language is unknown to me. I deem it to be a tongue of the Black Land, since it is foul and uncouth.

This writing, of course, was the Ring Inscription.

Answer 2

From The Fellowship of the Ring (book), this passage at least mentions the color.

As for Bilbo Baggins, even while he was making his speech, he had been fingering the golden ring in his pocket: his magic ring that he had kept secret for so many years.

As does this from the prologue, describing Gollum:

He possessed a secret treasure that had come to him long ages ago, when he still lived in the light: a ring of gold that made its wearer invisible.

Also from Wikipedia:

The words of the ring-inscription are in Black Speech, a language devised by Sauron and used in the land of Mordor. The inscription reflects the One Ring's power to control the other Rings of Power. The writing uses Elvish letters (tengwar), in a mode adapted to the Black Speech.

The Ring had the ability to change size. As well as adapting to fingers of varying size, from Sauron's to Frodo's, it sometimes suddenly expanded in order to give its wearer the slip

The size and shape is not as concrete as its color.

Normally the One Ring appeared perfectly plain and featureless, but when heated its inscription appeared in fiery letters. A drawing of the inscription and a translation provided by Gandalf appears in Book I, Chapter 2 of The Fellowship of the Ring, "The Shadow of the Past".

Gandalf speaks the words in Black Speech in Book II, Chapter 2, "The Council of Elrond":

"Ash nazg durbatulûk, ash nazg gimbatul,

Ash nazg thrakatulûk agh burzum-ishi krimpatul."

Translated, the words mean:

One ring to rule them all, one ring to find them,

One ring to bring them all and in the darkness bind them.

Answer 3

The Ring was a perfect circle of pure gold. The other rings of power had gems embedded in them, but the One Ring was just a plain band - except when heated, the fine lines of fire revealed the Tengwar script of Black Speech.

The size of the ring is a little dubious, it appears to be able to expand and contract to fit the wearer - be they the size of Isildur or that of Smeagol.

The Silmarillion mostly focuses upon events in the First Age, but there is a brief section at the very end concerning the Third Age and the Rings of Power. This describes how Sauron tricked the Elves of Eregion into forging the 19 Rings of Power, while he forged the One Ring himself.