On your turn, you may (1) collect chips (gems), or (2) buy and build a card, or (3) reserve one card. If you collect chips, you take either three different kinds of chips or two chips of the same kind. If you buy a card, you pay its price in chips and add it to your playing area. To reserve a card—in order to make sure you get it, or, why not, your opponents don't get it—you place it in front of you face down for later building; this costs you a round, but you also get gold in the form of a joker chip, which you can use as any gem.
All of the cards you buy increase your wealth as they give you a permanent gem bonus for later buys; some of the cards also give you prestige points. In order to win the game, you must reach 15 prestige points before your opponents do.