Basically, Enter the game while it is connected to the internet. Get to the screen where yous daily gems are, but don't collect them. Then exit and turn the internet off. When you re-enter the game, those gems should still be there, and the gift box in the top left corner should be there. Then just keep tapping on it and collect free gems. (I have already unlocked everything within the first day of getting this game)

P.S. I did this on an iPad2, so the likelyhood of it working on newer devices is smaller. Please let me know if it works for Android or newer iOS devices.