There was a bug in which the game wouldn't save your collected Gems upon ending a level. This is now fixed. The game will autosave all progress every time you pause (clicking the cog in the bottom right), so that is a viable work around if you are on the old version.

There still remains a bug in which the screen will tear/jitter. This happens most often when rotating while standing in place. I'm going to try to fix this issue as soon as possible.