I love this game so much, but they make it nearly impossible to play with out buying gems. In order to get 3 stars on a level you have to upgrade cooking items with gems, but in order to get gems you have to gain either experience points, complete all levels with 3 stars, or buy them. So you'll end up playing the same levels over and over again, doing everything perfectly and you'll be just a little bit away from 3 stars but never reach it until you upgrade things. It's nonsense.