Thank you for the feedback, that's helpful.
Yes, I'm aware of this, and it is kind of "handled", but definitely not the smartest solution from users view... Currently, if you are in such a state, you have to click on them (what costs 10 coins each time, because it's the start of a new turn) until you don't have enough to start a new turn, and game ends. So you kind of "in the end" are "punished" because you see your coins decreasing (and because of the incrementing turns also the score) if not played well enough before :-D
And additionally on the other side, if you have revealed all 8 gems, you get points for each one of them, as well as an extra (huge) bonus, for solving it completely.
But you are right, if i try to identify such states internally as "fail-states", could do the same logic automatically and directly show the game-over screen, what should be less confusing for players. Thank you :-)