Gem Stone Valley is the fifth and final hub in Crash Team Racing. Although it is the second hub world unlocked, it doesn't have a role in the game until all four Boss Keys are obtained. It is the main hub world of the game. 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. The entrance to the race with Oxide is here as well. Gem Stone Valley is connected to N. Sanity Beach and The Lost Ruins.
- Despite taking place in Citadel City, the player receives the Boss Key from the race with Pinstripe here. The cutscene of Pinstripe talking also takes place in Gem Stone Valley.
- 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.