Gemworld (also Elaysia) is a Federation member planet. It is home to the Elaysians. (TNG - Gemworld novels: Book 1, Book 2) Gemworld was once a world, but has since grown into a lattice of crystals, which have since consumed the world. Due to this it has had to be encased in a "Bubble" to contain the atmosphere, and gather energy and matter. There is no gravity inside the bubble, due to the crystal lattice. A destructive coup d'état was brewing on the planet in 2355. Admiral Presley requested that Elias Vaughn investigate. (DS9 novel: Lesser Evil)