Good one! At first I was trying to go back and get all the gems back but it turned out to be pretty difficult, so I had to suffer watching my precious gems get lost forever :(
Jokes aside, I liked the concept of not being able to go back or even stop to prepare a jump. Also I must confess that I had to give up after some time, the hitboxes are not very forgiving and I was always dying at the same spot, and the jump is a bit hard to control.
Solid game overall, good job on the pixel art and the lightning as well.