I got 51 in a couple attempts just now. I'm pretty sure I got a low 70 at some point when I first made this.
I remember I didn't want to start the timer till the first bounce but I probbly should have just vertically laid out the first gems so it wouldn't be random before the timer started. There could also be some tech in jump canceling to bounce faster at the expense of combos, but I think combos are the way to go for max points.