What is the inscription on J.R.R. Tolkien's One Ring written in?

The inscription on J.R.R. Tolkien’s One Ring is written in the Black Speech of Mordor.

The fiery inscription contains two lines from the Ring-verse: “One Ring to rule them all, One Ring to find them.” The complete verse also describes the other Rings and concludes with the phrase about binding them in darkness. The writing appears when the Ring is heated.

Tolkien created the Black Speech for Sauron and the servants of Mordor. It is distinct from Quenya and Sindarin, the Elvish languages most familiar from his legendarium. The inscription’s harsh sound and threatening meaning reflect Sauron’s attempt to dominate the other Rings of Power.

The inscription is not a translation into Elvish. In the story, the Elves originally made the Three Rings independently of Sauron’s direct involvement, but the One Ring was designed to control the other Rings. The language therefore reinforces its connection with Sauron and Mordor rather than with the Elves.