Fun and addicting! Very entertaining! You should consider making the DO NOT TOUCH gem appear faster.
Good enough a time waster especially if it's going to be on a tablet or phone. Two major flaws though;
Tapping on a spot will tap all of the gems on that point. This can lead to the player unintentionally hitting one of the forbidden gems. If this is meant to be played with fingers, that's gonna be a huge problem due to how inaccurate you could be.
The forbidden gems also become active during the "rolling" period, instead of as soon as the gem is displayed.
Overall it's okay. As for suggestions, try adding in more types of gems the higher your score goes!
It has got Eric Skiff. But for this game all you have to do is to click on all of the gems when ! appears. Otherwise, avoid that specific gems.
the gameplay isn't bad, could use some more graphics, different levels, powerups, highscores, charachters etc.
What a time we loose to wait the gem that we have to don't touch!