Every level, except for boss levels, consists of 3 different goals:
1. Complete the level under the time limit.
2. Complete the level in 1 bank.
3. Complete the level with no lives lost.
Each world is made up of 3 levels plus a final boss level. There are a total of 9 gems per world.
This achievement sounds complex, but it is not. You will most likely get this achievement after completing the boss level of the first world regardless of the character you use in the game. If you have trouble, try taking more time to collect the coins as you will most likely have extra time left anyways.
Here is a video showing different levels being completed with 3 gems: