How do I earn gems in Clash of Clans?

I play clash of clans and I'm at lvl 5 town hall. I need gems for some of the things I want to do. Other than spending real money, what things earn me gems?

Solution 1:

You can earn gems for free in the following ways:

1. Clearing up the trees, bushes, rocks, etc. that spawn around your village. Rocks do not re-spawn once you remove them.
2. Earning achievements in the game rewards you with gems. Check your achievement progress in-game to see how many you can earn and from what.
3. Once you've unlocked your Builder Base and reconstructed the Gem Mine, it will start producing gems for you.
4. Each league season, the top three clans are awarded gems, split equally among the top 10 players in each clan.

Solution 2:

You can also get gems by removing gem boxes which give 25 gems.

Solution 3:

The only (legit) way to get gems without paying real money is to destroy these rocks, stones and bushes all around your village. They will respawn after some time and have a chance to drop some gems (its not guaranteed that they always drop gems). Also you can get them for completing achievements.