Once you collect the required number of diamonds, the screen will flash white, and the Diamonds indicator will be replaced by a Bonus indicator, tell you how many points each subsequent diamond is worth. Alas, all is not so simple. There are objects in the caves that can help or hinder you. The blinking exit takes you to the next level. It appears when you have gathered enough diamonds.
Rocks fall when there's no ground underneath.
If a falling rock lands on you, it kills you. You can push rocks, and rocks can be destroyed in an explosion. You can dig through the ground by walking through it. Solid walls are indestructible. Walls can be destroyed by an explosion.