Once you have entered the mansion, make your way into the Mudroom. If you want, you can peek through the window and see a Polterpup did up the gem and throw it onto a tree branch. Go outside to the Mudroom Exterior and the gem out of the tree.
As soon as you have the ability to flash bright lights, head back to the Front Yard of the mansion. In front of the porch on the left are four purple flowers. Use a flash of light to allow them to bloom. The flower second closest to the door contains the second gem.
Make your way to the Studio on the second floor. Inside, find the grandfather clock and flash a bright light at the device on top. This should cause it to open, revealing the third gem.
Once you clear the Studio of any enemies, peer into the picture camera near the left wall. You’ll see the mirror on the right wall, but you will also see a reflection of the fourth gem stuck behind the curtain by some webs. Leave the camera and suck the gem down.
In the Entrance, interact with the guard statue on the right. Once the helmet pops off, suck it up with your vacuum and start moving to the upper left corner of the room. Point up and blow the helmet at the portrait of a helmet. The portrait will move, revealing the hidden fifth gem.
How often do you check the ceiling? In the Dining Room, head towards the right wall and look up. There should be a vault built into the ceiling. Open it with a flash of bright light to claim the sixth gem.
The Kitchen is home to many things, including the seventh gem. Open up the fridge to find a frozen gem. Suck it up with the vacuum and move it over the fire on the stove. Let it melt and pick up the seventh gem!
Now the Dark-Light Device comes into play. Out on the patio, head down the steps and reveal a hidden door against the left wall. Enter Under the Stairs and enter the next door. You’ll be back in the Foyer, but now behind the fish tank, allowing you to grab the eighth gem.
Head right back tot he Patio. If you look at the little pool of water, you’ll notice two Cheep Cheep statues. Use the Dark-Light Device to reveal a third statue that will spit the ninth gem out!
Enter the Library and make sure the room is clear of ghosts. Use the Dark-Light Device to reveal a hidden globe near the left wall. Suck the globe up and place it in the fire, revealing the tenth gem.
Let the bed throw you back into the Study, as the eleventh gem is hidden in this room. remove the curtains from the portrait near the window, and use the Dark-Light Device to pop the gem out.
Clearing the Master Hall of webs will gain you access to the Rafters. Up there, follow the wooden walkways until you reach the portrait of cheese or a flame. Move to the right and you should see a wardrobe with the twelfth gem on top.
Back in the Bedroom, the web ball attached to a string can be set on fire by the stove. Then the fan can be spun, letting the web ball hit the giant web blocking the gem. Walk behind the curtain changers and the thirteenth gem will be yours!