Gravesworld was a planet with a ring system.
In 2293, Gravesworld was located in or near Klingon space. (Star Trek VI: The Undiscovered Country)
In the mid-24th century, Dr. Ira Graves lived and worked here, along with his assistant Kareen Brianon, until his death in 2365. The nearest starbase to the planet was Starbase 6. (TNG: "The Schizoid Man")
Gravesworld appeared in the starchart Data and Picard were studying in Stellar Cartography in 2371. (Star Trek Generations)