Also, there's the fact that they are worth points in single player and used (a lot) in treasure. They are Jazz 2's answer to "the useless item that is for nothing except getting points" in many ways, though I'm sure they weren't intended to be that way. If you go through the training level, it is stated that a hundered gems equals one life. Of course, they never actually added this to the game, but at least it sheds some light on what they were intended for.

Not to mention there would be no treasure mode without gems. Without treasure mode, there would be no mode where it was impossible to kill opponents, (excluding server types you can get to work, kind of, with XJJ2) so several gametypes would not exist.

They are still pretty useless in single player, though they make levels look more professional when used well.


Trafton: clarification edit.