There are two race tracks in Gem Stone Valley: Slide Coliseum and Turbo Track, which the players cannot access until they get ten relics and all five gems, respectively. There is also a room where the Gem Cups can be accessed, but two Boss Keys are needed to enter and at least three are needed before the first Cup can be unlocked. Gem Stone Valley is connected to N. Sanity Beach and The Lost Ruins.
The name of this hub world presumably came from the Gem Cups being located in this area. However in the Nitro-Fueled version, the hub is filled with sparkling gems and crystals to closely reflect its name. Oxide's hologram face can also be seen in this version, menacingly watching the player.
- Slide Coliseum
- Turbo Track
- Red Gem Cup
- Green Gem Cup
- Blue Gem Cup
- Yellow Gem Cup
- Purple Gem Cup
- Nitros Oxide's Challenge (Oxide Station)
- Despite the race with Pinstripe taking place in Citadel City, the player receives the Boss Key in Gem Stone Valley. The cutscene of Pinstripe talking also takes place in Gem Stone Valley. This was fixed in the Nitro Fueled version of the cutscenes, with Pinstripe's intro cutscene taking place outside his boss gate in Citadel City and his loss cutscene taking place in Hot Air Skyway.
- Oxide's spaceship is shown to have landed here, but in the opening cutscene of the game, he came down to Earth in his hover-ship.