RAINBOW ISLANDS TOWERING ADVENTURE

You can collect all diamonds in any level, but if you just want the achievement, I would recomend playing on the first one. They are really useful if you keep getting them on each level, though.

In order to get a diamond, you have to either kill enemies with the stars that fall everytime you break a rainbow (by jumping through the bottom of it or by pressing down) or with a star item. Once you get a star item, some stars will be shot, and all enemies that get hit by it will turn into diamonds.

Depending on the enemy position after dying, you will get a different colour. If the enemy is killed on the left, you will get the red. If you kill him a little more on the right, it will be orange... And if you kill him on the right side of the screen, it will be purple.

Easiest way to get many diamonds is using the stars, but that way is harder to control which diamond you will get. Once you have just a few left, try making many rainbows above the enemies and then pressing down.

Diamonds are really useful, because if you reach the boss with them, they´ll do around 1/2 of damage to him, so it´s a lot easier to beat them.