Gemstone

Gemstones are very well hidden items in Luigi's Mansion 2. There are five different types for each mansion;

File:250px-GemstoneLMDM.PNG

Luigi collecting Gloomy Manor's third Gemstone in the Parlor

Amethysts are in the Gloomy Manor. Emeralds appear in the Haunted Towers. Rubies are in the Old Clockworks. Sapphires are in the Secret Mine, and diamonds are in the Treacherous Mansion. Each is hidden very well, and the player must have a keen eye to spot clues to where they are. For each mansion there are 13 different gemstones, each with a different shape. Collecting all the gems will unlock a special statue of Luigi for the player to admire. It is decorated with the gems that were collected.

The locations for each are recorded below:

Gloomy Manor

Shape	Image	Missions Available	Room	Obtaining
Circle	File:Lmdmgems1.png	All	Mudroom Exterior	Use the Poltergust 5000 to take it down from the tree.
Triangle	File:Lmdmgems2.png	All	Front Yard	Use the Strobulb to make the flower in the middle of the patch to the left of the staircase bloom. It will give the gem.
Rectangle	File:Lmdmgems3.png	All but A-1	Parlor	Use the Strobulb on the clock.
Football	File:Lmdmgems4.png	All but A-1	Studio	Looking through the camera will let the player see the gem through the mirror. Aim out the window and suck it up.
Tear	File:Lmdmgems5.png	A-3 and Bonus	Entrance	Check the suit of armor on the right to make it's head fall off. Suck up the helmet and shoot it at the painting of a knight head. It will open up and make a gem appear.
Stone	File:Lmdmgems6.png	A-3, A-4, A-5, and Bonus	Dining Room	Find the safe at the right side of the room on the ceiling and use the Strobulb on it.
Rhombus	File:Lmdmgems7.png	A-3, A-4, A-5 and Bonus	Kitchen	Open the fridge to reveal the gem encased in ice. Then check the furnace to start a fire. Suck up the ice block and move it over to the fire, freeing the gem.
Star	File:Lmdmgems8.png	A-3, A-4, A-5 and Bonus	Foyer	In the Patio, go left and use the Dark-Light Device on the wall, revealing a door to Under the Stairs. Go though the next door to end up on the other side of the fish tank, allowing access to collect the gem.
Octogon	File:Lmdmgems9.png	A-3, A-4, A-5 and Bonus	Patio	Use the Dark-Light to reveal the third fountain that's next to the other two.
Oval	File:Lmdmgems10.png	A-3, A-4, A-5 and Bonus	Library	Reveal the globe at the left side of the room. Suck it up and shoot it our for the gem.
Spindle	File:Lmdmgems11.png	A-2, A-3, A-4, A-5 and Bonus	Study	Suck up the curtains on the back wall to uncover a painting of the gem. Use the Dark-Light to make it a reality.
Coffin	File:Lmdmgems12.png	A-5, and Bonus	Rafters	Go to the lower-right corner of the room, with the dresser. The gem is in plain sight, resting atop the dresser.
Mushroom	File:Lmdmgems13.png	A-5, and Bonus	Bedroom	Burn the webs with the spider web. Go behind the covers to obtain the final gem.

Haunted Towers

Shape	Image	Missions Available	Room	Obtaining
Circle	File:Lmdmgemsht1.png	All	Tower Lobby	Walk behind the stairs to find and obtain the gem.
Triangle	File:Lmdmgemsht2.png	B-1 and Bonus	Laboratories	Use the Balloon Berries to fly down into the glass chamber from the floor above.
Rectangle	File:Lmdmgemsht3.png	B-2, B-3, B-4, B-5, and Bonus	Garden	Fill up a bucket with water, and water the flower on the right side of the Garden. It will reveal a gem.
Football	File:Lmdmgemsht4.png	B-2, B-3, B-4, B-5, and Bonus	Botany Lab	Fill up the bucket in the room with water, and water the plant in the back of the room. It will reveal a gem
Tear	File:Lmdmgemsht5.png	B-2, B-3, B-4, B-5, and Bonus	Seedling Laboratory	After clearing the room, use the potato shooter to shoot the mouse carrying the gem, then collect your reward.
Stone	File:Lmdmgemsht6.png	B-3, B-4, B-5, and Bonus	West Garden	Reveal some pipes using the Dark-Light on the stairwell of the Tower Lobby, and then reveal a door on the left side of F1 in the Tower Lobby. Use the hitchhiker plant to kill the Carnivorous Plant. Open the chest.
Rhombus	File:Lmdmgemsht7.png	B-3, and Bonus	Hollow Tree	Use the cobwebs to burn your way through the left tunnel. Take the bucket from the left and fill it with water. Then go right to water the plant. Use the Strobulb for your reward.
Star	File:Lmdmgemsht8.png	B-3, B-4, B-5, and Bonus	Old Cemetery	Take it down from the tree branch it sits upon, just before the main part of the graveyard.
Octogon	File:Lmdmgemsht9.png	B-4, and Bonus	Skybridge	Defeat the Orange Flowers to get the gem.
Oval	File:Lmdmgemsht10.png	B-4, and Bonus	Rumpus Room	Walk around the doll counter-clockwise to pop its head off and find the gem.
Spindle	File:Lmdmgemsht11.png	B-4, B-5, and Bonus	Solarium	The the Dark-Light to reveal a chest on the table. It contains the gem.
Coffin	File:Lmdmgemsht12.png	B-4	Conservatory (Luigi's Mansion 2)	Using a Balloon Berry to fly to a balcony to the right, use the Dark-Light to uncover a door. Go in the door and beat the challenge to earn a gem.
Mushroom	File:Lmdmgemsht13.png	B-4, B-5, and Bonus	West Bathroom	Defeat all the ghosts and pull on the toilet paper to the left.

Old Clockworks

Shape	Image	Missions Available	Room	Obtaining
Circle	File:Lmdmgemsoc1.png	All	Clockworks Court	Go far right and use the Dark-Light on the tool box containing a gem.
Triangle	File:Lmdmgemsoc2.png	All	Warehouse	Use the Dark-Light to reveal a green barrel on the boxes. Use the machine in the room to reveal the gem.
Rectangle	File:Lmdmgemsoc3.png	All and Boss	Clock Tower Gate	In the top-left corner of the room, use the Dark-Light on a tool box containing a gem.
Football	File:Lmdmgemsoc4.png	All but A-1	Storm Cellar	Suck up the sheet in the bottom-left, and use the Dark-Light on the painting.
Tear	File:Lmdmgemsoc5.png	All but A-1	Canyon Stairs	There is a ruby stuck in a web that you'll see as you go up.
Stone	File:Lmdmgemsoc6.png	All but A-1	Quarry	Pull the mine cart so that Luigi can go into the tunnel behind it. This will lead to several Golden Bat (Luigi's Mansion 2), and the gem.
Rhombus	File:Lmdmgemsoc7.png	C-3, C-4, C-5 and Bonus	Clockmaker's Chambers	Suck up the rug to find a gear. Use the gear to turn the clock to 9:00, which will wake up the ghost holding a ruby. Defeat it to get the gem.
Star	File:Lmdmgemsoc8.png	C-3, C-4, C-5 and Bonus	(Upper) Roundhouse	Walk along the rightmost beam, on the balcony of the Roundhouse. walk around the corner to find a chest with a gem.
Octogon	File:Lmdmgemsoc9.png	C-3, C-4, C-5 and Bonus	(Lower) Roundhouse	From the stairs leading to the (Upper) Roundhouse continue going left into a secret area with a gem.
Oval	File:Lmdmgemsoc10.png	C-5	Gear Chamber	Go across the boxes on the right side of the bottom part of the room, revealing a bridge along the way. Go into the hidden door and complete the challenge to get a gem.
Spindle	File:Lmdmgemsoc11.png	C-5 and Bonus	Maintenance Hub	Use the hipline to fall into the bottom of the room. Reveal a chest in front of the giant gear. The gem is inside.
Coffin	File:Lmdmgemsoc12.png	C-5	Service Elevator	After getting Toad, launch him towards the screen. He'll collect some Secret Mines
Mushroom	File:Lmdmgemsoc13.png	Boss and Bonus	Movements	Walk to the window on the left and vacuum for a gem.

Secret Mine

Shape	Image	Missions Available	Room	Obtaining
Circle	File:Lmdmgemssm1.png	All	Smokehouse	Use the Dark-Light to reveal a scarf on the wall, then pull both of them off.
Triangle	File:Lmdmgemssm2.png	All	Fishing Hut	It's hidden in the bottom-left. The player can see it from the hole outside the hut. Use the Poltergust 5000 there to get it.
Rectangle	File:Lmdmgemssm3.png	D-1	Under the Ice	Shoot Toad into the wooden shaft after riding the first air geyser.
Football	File:Lmdmgemssm4.png	All	High Wires	Use the zip lines to cross the first chasm, and take the gem down from the bird's nest.
Tear	File:Lmdmgemssm5.png	All	Airway	Look through the binoculars at the entrance to the Terminal. Look for the dark cave and you'll see a bat go from the cave and drop the gem into a barrel. Go collect it afterwards
Stone	File:Lmdmgemssm6.png	All but D-1	Chalet Approach	Outside to the left of the entrance is a stove, with a chicken on top. Light the stove and use the flaming chicken to melt the ice around a painting outside. Use the Dark-Light on the painting, and collect the gem.
Rhombus	File:Lmdmgemssm7.png	All but D-1	Prospector's Crossing	On the lower left wall is an axe that is hidden with Spirit Balls. Uncover it with the Dark-Light (there is a hidden arrow pointing to it in the ice). Use the Poltergust 5000 on it to find two logs. Put both on the ice to break it, and collect the gem that was inside.
Star	File:Lmdmgemssm8.png	All but D-1	Skip Slope	While sliding down be prepared to go to the left. There will be a big spinning wheel blocking a path to a gem. The player must slide through one of the holes in the wheel to get it. This may take a couple of tries.
Octogon	File:Lmdmgemssm9.png	All but D-1	Shaft	Pull the chain at the bottom of the Shaft, then climb back up to a hatch that was previously closed. The gem is inside.
Oval	File:Lmdmgemssm10.png	All but D-1	Deep Hall	Light a piece of coal, and look up. There should be a gem encased in ice above. Shoot the coal at the ice to melt it and ma,e the gem fall to the ground.
Spindle	File:Lmdmgemssm11.png	D-3 and Bonus	Crossroads	Go to the left side and find the missing mine cart with the Dark-Light. Quickly go over to the right side to capture the Spirit Balls. Return to the left side to find the gem hidden in the snow.
Coffin	File:Lmdmgemssm12.png	D-3, and Bonus	Chalet	Go to the very bottom of the mine, in the Crystal Quarry. In that room there should be a portal that can be activated with the Strobulb. Go though and you'll end up in the Chalet. Luigi will land on a chair, knocking the gem from it's hiding spot.
Mushroom	File:Lmdmgemssm13.png	D-3	High Wires	Use the coal shooter to melt the ice on the tree. Go cross the tree to an outhouse. Go inside and hit the three Hiders with snowballs to win a gem.

Treacherous Mansion

Shape	Image	Missions Available	Room	Obtaining
Circle	File:Lmdmgemstm1.png	E-1 and Bonus	Underground Lab	After turning the wheel to maximum poser to zap the armor, use it's helmet to knock down the beakers. One of them has a gem.
Triangle	File:Lmdmgemstm2.png	E-1 and Bonus	Haunted Catacombs	After the Underground Lab, follow the direction the suits of armor point shen checking them. At the last tunnel with no suits of armor, go to the farthest back point and go right. Use the Dark-Light on the painting of a spider web and light it with the fire nearby. Burn the webs you saw along the way for a gem.
Rectangle	File:Lmdmgemstm3.png	E-1 and Bonus	Cliffside	From the Underground Lab door go right, down, right, and up twice. This will lead you to a door that goes to the Cliffside. Take the gem down from the vine.
Football	File:Lmdmgemstm4.png	E-2, E-3, E-5, and Bonus	Front Entrance	Reveal the missing chain attached to the gargoyle statue. Pull it and open the safe under the stairs for a gem.
Tear	File:Lmdmgemstm5.png	Restrooms	Pull the chain on the toilet in the western side of the room.
Stone	File:Lmdmgemstm6.png	E-2 and Bonus	Gargoyle Roof	Pull on the mammoth trunk in the Ice Age Exhibit to access the Gargoyle Roof. Find three stars around the "room" and shoot them into the giant star made of smaller stars. A gem will fall from the sky upon completion.
Rhombus	File:Lmdmgemstm7.png	E-2, E-3, E-5, and Bonus	Ancient Exhibit	Water the spout close to the door, and use the Strobulb on the plant that appears. A gem will pop out. You can find the bucket in the Dark Age Exhibit and the water in the Jungle Exhibit. Use portals to traverse.
Star	File:Lmdmgemstm8.png	E-3, E-5, and Bonus	Aviation Exhibit	Pull all of the sandbags off the hot air balloon.
Octogon	File:Lmdmgemstm9.png	E-3, E-5, and Bonus	Nautical Exhibit	Place something like a log or a bucket of water of the life savior on the ship to make the wheel go down. Go out to the end of the ship and open the chest with a gem in it.
Oval	File:Lmdmgemstm10.png	E-3, E-5, and Bonus	Dark Age Exhibit	Using a Balloon Berry, fly up and right to find a gargoyle with a blue book. Use the Strobulb on it to make it drop the book and fly back down. Put that book into the bookshelf in the Dark Age Exhibit.
Spindle	File:Lmdmgemstm11.png	E-3	Jungle Exhibit	Either use a Balloon Berry or enter from the East Balcony to get to the top part of the Jungle Exhibit. Find the Golden Balloon Berry and collect all the coins for ca chest with a gem in it.
Coffin	File:Lmdmgemstm12.png	E-3	Ice Age Exhibit	Use a Balloon Berry to fly to the tiop left portion of the Ice Age Exhibit. Collect all the coins from the Golden Balloon Berry for a chest with a gem in it.
Mushroom	File:Lmdmgemstm13.png	E-3, E-5, and Bonus	Train Exhibit	Use the Dark-Light on the missing track in front of the door. Afterwards ride the train once for a gem.