If you’ve opened your village to find that gems have gone missing, it’s because they’ve somehow been spent. Usually, it’s just because another person has used the gems (like a friend or family member). This is also likely if you’ve loaded your village onto someone else’s device, and didn’t sign off. They could be playing the account without you being aware of it. 

The game cannot use gems on its own, purchases must be requested by the user. Accidental purchases are a possibility, though we’ve added a series of intuitive confirmation steps to prevent this. 

In order to prevent these instances from happening in the future, please remember to lock your screen after playing. As well, if you’ve loaded your village onto someone else’s device, remember to log out when you’re done.