There are six collectible gems on each floor in Luigi’s Mansion 3. In this guide, I’ll show you where to find all six gems on the B2 floor and tell you how to get your hands on them. You’ll need to unlock certain abilities before you’ll be able to collect some of these gems, so you may have to come back later on in the game.
Please note that some of the gems will appear clear rather than coloured in the screenshots seen below, this is because I had already collected them during my playthrough before creating this guide.
Gem #1 – Elevator Hall
Use your vacuum on the cloth which is inbetween the two pipes to reveal a third pipe in the middle. Use Gooigi to slip through this pipe to get to the raised platform on the right hand side of the room. Once on the platform, keep running to the left and you’ll get all the way up to collect the Yellow Gem.
Gem #2 – Storage Room
Head into the Storage Room and perform a Suction Shot on the bucket to reveal a second pipe to the left of the first one. Use Gooigi to slip through this pipe and you’ll come out on the left hand side of the room next door. Now, take control of Luigi and use your vacuum to shut off the valve back in the first room, turning off the water in the second room. Then, take control of Gooigi again and slip through the pipe on the right hand side of the second room, which you can get to now that you’ve turned the water off. Going through this pipe will send you to a basement room below, but you’ll need to take control of Luigi and blow air at the valve again to shut off the water in the basement room so that you can grab the Red Gem.
Gem #3 – Observation
In the Observation room, use your vacuum on the office chair to move it out of the way, revealing a green light behind it. Now, move to the bottom end of the room (towards the camera) and use your Dark Light on the table below the pipe to make a pot appear. Now, head back to the top of the room and use your Strobulb on the green light to overflow the coffee machine, which will spill on the machinery, causing it to short out and throw out the Blue Gem.
Gem #4 – Sewer C
Once you’ve lowered the water level, run back through Sewer C. Just over half way back down Sewer C you’ll see what looks like a pipe coming out of a crack in the ground. Use a Suction Shot on this pipe to rip the cover off, then use Gooigi to slip through the pipe into a submarine below. Now use your vacuum to pick up the flaming torch and carry it over to the right side of the submarine to light the wood underneath the cooking pot. After a few seconds the Purple Gem should jump out of the pot.
Gem #5 – Sewer B
Now run back down Sewer B. When you get to the bottom of the corridor, summon Gooigi and stand him on the metal lift to your right. Now take control of Luigi and use your vacuum to pull the chain on the wall next to it to raise the lift. Keep hold of the chain and switch back to Gooigi, and use his vacuum on the Green Gem, which is stuck in a chain just above him on his near side. After a few seconds of using the vacuum the gem will break loose and drop down to Luigi.
Gem #6 – Old Reservoir
Later on in the game you’ll be forced to backtrack to B2 for reasons which I won’t say here to avoid giving anyone any spoilers. When you do this backtracking you’ll have to venture into a new part of the floor which will take you to the Old Reservoir. Once you’re in there, get down to the ground floor and head to the upper left corner of the room where you’ll see a bunch of paint cans next to a wall which is set back. Use your vacuum to suck up a paint can and fire it at the wall – do this a few times until a ghost appears. Defeat this ghost and you’ll be rewarded with the Clear Gem.
And that’s it! Congratulations, you collected all six gems.