A permanent part of the Heads Up Display at the bottom-center of the screen, the 'Light Gem', or 'Visibility Gem' indicates to the player how visible Garrett is, by brightening or darkening according to the light-levels of Garrett's position, and tells the player how well guards or other NPCs in the vicinity may be able to see Garrett, if they are facing him or looking in his direction.
In Thief: Deadly Shadows, the Light Gem is integrated with the Compass, while in the other games the compass is a separate inventory item. Also, the darkest shade is represented by a deep blue, while in the other games, Thief: The Dark Project and Thief II: The Metal Age, the darkest shade is nearly black with a tinge of green and there's a tiny secondary indicator on the right end of the gem, which changes from black for safe, to yellow for caution, and red for dangerous.
|Games||Thief: The Dark Project · Thief Gold · Thief II: The Metal Age · Thief: Deadly Shadows · Thief (reboot)|
|Game Design||Storyline · Lighting · Sound · Weapons · Abilities · Light Gem · Compass · Loot · Approach · Architecture · Cut scenes|