Gemworld is 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. AdmiralPresley requested that Elias Vaughn investigate. (DS9novel: Lesser Evil)
Gemworld has 6 species living on the planet they include the Yilltern, Lipul, Frills, Elaysian, Gendlii and the Alpusta.