Cool game! Guiding the diamond with the mouse, whilst still trying not to get too close is a cool idea. Unfortunately, it doesn't seem to work entirely as it's supposed to, as when I kept my mouse completely still the diamond just started shaking on top of the mouse. The game was somewhat hard, but I think it's just hard enough that it doesn't feel frustrating to play, and still feels satisfying when you manage to complete a level.
As for possible improvements, it could of course do with some more levels and mechanics (although I obviously understand that you didn't have time to make more). It also feels like it could use some better visuals, as well as some more audio, for example music and more sound effects.
But overall, nice game!