I just want to mention there is no reward for Practice game sometimes.
I note every win- before I reach 300 gems I can't get more crystals in some cases. When I change difficulty level to another (from expert) or start the same level one more time I can get more crystals again (not everytime).
Try to fix it, Bethesda
There is still NO REWARD for winning Practise Game sometimes.
There is no point play this mode if I have to win 27 games, instead of 20, to get 300 crystals.