Hey

It seems you remove gems before the drawing.
I had 2 different use cases yesterday:

* I had 200 gems, I opened a premium crate, the gems have been removed, the game was frozen and nothing happened.
* I just a finish a alliance round, the game was loading reward crate, the game was frozen and nothing happened.

Both I was in my car and my internet connexion was bad.

You should remove gems/gold/etc in the same time you add an item to the player in your API side.
In this ways, we will have the item even if there is a timeout or whatever in the game side.