2/ Get the gem, the key and the torch.

3/ Blow up the dynamite on the left-hand side to get the gem and the torch.

4/ Blow up the dynamite above and get the gem.

5/ Go quickly over the trap to get the torch and then blow up the dynamite to the right.

6/ Go down to get the gem, then get the torch (don't pass next to the dynamite on the left).

7/ Get the gem and blow up the nearest dynamite to get the other gem.

8/ Get the two gems at the top on the way to the door.

(It's impossible to get the other gem.)