The ring of stone is an enchanted onyx ring. It can change the avatar of the player to look like that of a stone or empty Mining rock. If the player moves while under the effect, the effect will end. If another player mouses over or right-clicks on the player-turned-rock, the normal options will appear (“Walk here (Player name),” “Follow (Player name),” etc.).
The ability to disguise as a rock is sometimes used at Lava Maze runite mine right next to the runite ore rocks to skull trick unaware runite ore miners.