i need a detailed description of how to get the third fragment of the jewel. I know where it is hidden and i about the rock but i don't know how to get out of the cave after i have opened the box.
plz help me

I am willing to help you, but I don't know what level you are talking about or what diffuculty you are on, but if you are talking about the last cave in monsoon jungle after you open the vortex, here is where it is.
Normal diffuculty: enter the door. You should see the box to your left. Open it and get the gem. Next, crack the rock and crawl-jump through the passage. Exit the cave.
Hard diffuculty: Enter the door. Climb the ledges until you are on the other side. Turn to the left wall and do a bash-jump (b+a). Go in the room and get the baseball. Throw the baseball at the rock and then crawl through the passage. Carry the ball up the ledges you first came from and
power-throw it at the block above the ladder. Climb up the ladder and go into the room. The gem piece is there.