There are plenty of ways to earn gems in Clash of Clans. You can earn gems by clearing natural obstacles objects like trees, rocks, trunks,… And you will get more gems after a completed mission.
And there is always a problem with us while playing free-to-play game, the premium boost system. When you upgrade something in game, you need to wait for a long time. And it will be more and more longer if you do more progress. Keep calm, do patient, not be hasty, don’t spend your gems on these things, you need gems to the most important things. Please save gems as many as you can, even you shouldn’t use gems in the tutorial session. If the time have knock you down, don’t worry, come and play other games or watch movies to cycle through them.
It’s hard to think about how to use these gems in reasonable ways. But I think the most reasonable way to use our gems is buying new builders.
Read more about spends gem at: How to spends gem in Clash of Clans.