Hi Chief,
Thanks for contacting us and playing Clash of Clans!
I am sorry to hear that some of your gems are missing. Gems are always used to perform an action in the game like buying resources or speeding up construction and training.
However, if you still aren't sure how you spent your gems, please give me some more details and I will be happy to look into it. What day did it happen and how many gems do you think you lost?
Clash on!