Anyone here bought the mystic rose?

The effect goes like this: You show a cardboard who is flat and there's nothing hidden in it to the spectators. Next, you fold the cardboard into a cone and the top is also covered by the cardboard. Next you ask the spectator to choose an envelope which actually determines whether the rose is white,green,red or yellow. Almost instantly, a rose of the colour the spectator picks rises up within the closed up cardboard.

I have tried this trick, but its so difficult to master. Anyone here could do it smoothly?