Reading of the CRuby (MRI) source code provides unparalleled insight into the Ruby language. During the talk we will add new native Graph data type to CRuby. The new Graph data structure will be simple but on par with other native types such as Array or Hash. This talk will demonstrate that it is easy to experiment with CRuby and extend it in C. We will experience the speed advantage of using C to boost Ruby performance. We will implement a few of the greatest hits of graph algorithms: Breath First Search, Dijkstra, and Minimum Spanning Tree.