Nice game!
A few things though, the meta of the game seems to be just picking one gem and trying to remove other types of gems and add more gems of that type. So all blue gems, or green gems with wildcard (fire) gems. So it's pretty simple, I think it could be done better by focusing on those mods the gems have (they barely seem to have any purpose). Also some progression would help, and maybe the goal instead of the crown could be to beat level a 100 monster.
Also there's a bug where the "buy people" price goes to high numbers, then goes back to $0 for a few purchases and then up again...
Hope the feedback helps, it was a fun little game.