Really nice entry! The art was very cohesive, the music catchy, and the concept fun.
However I had some issues jumping as well, they do not jump like in the video, not nearly as high... Also of note the yellow one seems to be able to double jump if you tap jump quick enough and aren't right up against a wall. It's the only way I was able to progress. Really not sure why...
Otherwise my only suggestion: I think some type of throw strength indicator would help. It's currently hard to predict how far the gem is going to go.