For the pink gem, you require to have the mirror found in the game's starting area in your inventory, as well as to have Piettertje Muis in your helper inventory slot. Piettertje is the mouse character.

With these two items in your inventory, go to Anderrijk, and from its main area go upwards toward the mirage. When at the mirage, click on Pardoes to grab the mirror, and use it to click on the mirage's entry way. This will make Pardoes enter the mirage.

When there, click on the straw basket most in front to move it aside. This will reveal a cheese. Grab Piettertje out of your inventory and move him to the cheese. When done successfully, you will receive a doorknob in your inventory. Grab the door knob out of your inventory, and place it on the door without a door knob that is on the left side of the screen. The door opens and there is the pink gem.