Notice the locked door outside the manor in Blue Prince? That door leads directly to the Gemstone Cavern. The lock is tied to a puzzle that you must solve to get access to the location, which among other things, is required to use one of the Gas Valves.
In this guide we will go through the entire process of solving the Gemstone Cavern door puzzle in Blue Prince.
The game does give you some hints to unlock the door. There are colored lights in on the panel in the Utility Room aka the VAC system lights.
The solution is to get the lights set in the right order to open the door.
Gemstone Cavern Door Solution
The correct sequence of lights on the Utility Box is:
- Off
- Blue
- Green
- White
- Red
- Purple
Once you match this sequence, the Gemstone Cavern will become accessible to you in Blue Prince. You need to press the large switch that appears after using the correct sequence.
