There's a daily drawing in Dragon City, where you choose one of the cards and get a reward. Between drawing the cards are shown to you, and there are various rewards including crystals. But as for now, I've got only the lowest value rewards.
Is that drawing really honest? By honest I understand, the cards are really mixed and you have the same probability to get each of rewards. I can't exclude I've had misluck, but maybe it's not a real drawing, and it doesn't matter what card you click, an algorithm decides what you get.
Answering that questions would require, of course, a large series of tries and summing up the information from the other players.