For the light blue gem, grab the mirror found in the game's starting area, then go to the Anderrijk area.

From the Anderrijk main area, take the middle path to the mirage. At the mirage, grab the mirror and use it to enter the mirrage.

At the mirage, click the opening of the window in the top right corner. This will drop a key onto the ground. Grab the key and go to the Marerijk area.

In the Marerijk main area, take the path on the right to Villa Volta, represented by the goat horns. There use the key just gotten on the doors of the villa to open them. Enter the villa, and the villa's puzzle will automatically start. During this puzzle you can NOT walk out of the villa. The only way to get out is by using Belletje Bel.

The goal of the puzzle is to slide the five blocks in the image on the couch until a face forms. Once completed, the mansion will return to normal. Grab the bucket that has the water in it. Then grab the bucket out of your inventory and pour it onto the fire. You can then grab the gem as fast as you'd like without fearing the game crashing.