In the Underground Lab, spin the valve to give the knight a jolt of electricity causing its helmet to pop off. Suck up the helmet and aim it at the glass jar on the right side of the room. Blast the helmet at the jar, releasing the first gem.
In the Haunted Catacombs, take the following route to find an area with a portrait of a spiderweb ball painted on it:
Use the Dark-Light Device to bring forth the spiderweb ball and have it lit with the torch nearby. From here, go:
Then you should find a web covered on the wall. Burn it to reveal the second gem.
Again in the Haunted Catacombs, go:
Now you should see a door on the left. Enter it and you should see the third gem hanging from a vine.
Once inside the Front Entrance, use the Dark-Light Device to reveal a missing gargoyle on the right. Pull on the rope to reveal a hidden safe under the stairs. Before you can grab the fourth gem you’ll need to fight off a Strong Slammer.
In the Grand East, reveal a hidden door next to the Restrooms door. Inside is the west section of the Restrooms, and you can find the fifth the gem by pulling on the rope.
Pull on the trunk of the mammoth in the Ice Age Exhibit to have it throw you right through the ceiling. Now on the Gargoyle Roof, find three missing stars and shoot them at the star constellation in the sky, One should be on the floor, another is in the mouth of the gargoyle on the left, and the last star should fly across the screen occasionally. Completing the constellation will grant you the sixth gem.
Once you have the bucket from the Dark Age Exhibit, use the portal devices to get water from the waterfall in the Jungle Exhibit, then head to the Ancient Exhibit where a sprout needs water on the upper floor. A purple flower will grow with the seventh gem inside.
In the Aviation Exhibit, pull off the sandbags from the hot air balloon to allow it to rise and open the hatch below. This will release the eighth gem.
Using either the bucket from the Dark Ages Exhibit or the Yellow Book from the Study, head into the Nautical Exhibit and place the object on top of the switch on the ship. This will allow you to use the door on the right where the ninth gem waits in a treasure chest.
Using the portal devices and a purple balloon from the Study, head to the Front Entrance and float up to the two gargoyles on the right side of the room. Release the blue book from the gargoyle’s mouth and take it over to the Dark Ages Exhibit. Place it on the bookshelf to reveal the tenth gem.
Using the portal devices and a purple balloon from the Study, enter the Jungle Exhibit and flout to the upper level of the room. Here you will find a golden balloon that will activate a timer and rings of spinning coins. Capture all the coins by collecting the coins in the opposite direction that they are moving.Taking out the crows beforehand will avoid any problems during the timed sequence. If you collect all the coins before the timer runs out, a chest will appear with the eleventh gem inside.
Using the portal devices and a purple balloon from the Study, float to the upper level of the Ice Age Exhibit where a single golden balloon waits. Grab it to start off a timer and a row of moving coins. Collect them all by using the air currents of the vents to help move you along. If you collect all the coins before the timer ends, a chest will appear with the twelfth gem inside.
In the Train Exhibit, use the Dark-Light Device on the train tracks to reveal a missing piece. Hop on the train to have it take you through the back room. Upon returning, the thirteenth and final gem will be in your hands!