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 4F 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
As soon as you exit the elevator you’ll see a tuba in the corner. Blow air into the mouthpiece end and you’ll see the Purple Gem appear out of the top. Keep blowing air and take control of Gooigi, then use his vacuum to get a hold of the gem.
Gem #2 Elevator Hall
Now head left and run right to the end of the hall where you’ll find a popcorn machine with a green light on. Use your Strobulb on the light three times to fill the machine until it bursts and spits out the Yellow Gem.
Gem #3 – Concession Stand
Head into the Restroom (the door on the right in the open area just next to the popcorn machine). Take control of Gooigi to head through the small fence on the right hand side of the room and use your vacuum to pull the chain, causing the Ghost on the wall to open its mouth. Take control of Luigi and press X on the Ghost and you’ll soon find yourself in the Concession Stand. Here, use your vacuum on the bottles at the top of the room, moving slowly from left to right to play a tune. Doing so will open up the safe in the top left corner of the room, granting you the Blue Gem.
Gem #4 – Restroom
Head into the other Restroom opposite and use your Dark Light on the first sink as you walk in. Use the newly-appeared tap and a Ghost will appear – defeat this Ghost and you’ll be rewarded with the Clear Gem.
Gem #5 – Auditorium
Head into the Auditorium and get on to the stage. You’ll see a distinct square on the floor just in front of the painting – stand on it and perform a Burst and a plug socket will come up from underneath the stage. Plug your Poltergust into the socket (you’ll need the super socket upgrade to be able to do this one) and vacuum up all of the wall at the back of the stage, then suck up the ghost orchestra which you’ll find behind it. Use your Strobulb on the TV at the back, then press X on it to transport to the balcony. Use your vacuum on the box of popcorn and you’ll also suck up the Green Gem.
Gem #6 – Dressing Room
Head to the left of the stage and go behind the curtain and you’ll get an X prompt. Press X and you’ll go through a door into the Dressing Room. Use your Dark Light on the piano in the corner and then play it, causing it to spit out a whole load of money and the Red Gem.
And that’s it! Congratulations, you collected all six gems.