The Purple Jewelis one of the five missing jewels that you will find in Nabooti Island. which is you main mission in this island. Once you complete all the missing five jewels, return to the Nabooti Museum and receive your reward.
How to get the Purple Jewel
On the Blue Nine Falls, jump above the hills and you will find a woman that needs help in moving her Fox, Chicken and Feed on the other side. Help the woman and she will tell you about a hidden cave behind a bush on the right side of the waterfall. Jump down and to the right. If you set it up correctly, you’ll land right in front of the cave. Click on it to go inside. There are several narrow platforms you need to jump across inside the cave. If you fall down, just jump back up on the left side and try again. Watch out for the stalactites that fall from the ceiling. When you get to the end, you’ll find the purple jewel of Nabooti.