Crochet 4 Tone Grannies
This concept can be used to make it 2 tone or even just 1/4 tone if you want. The secret is to turn the project back in the direction from which you came at the end of each round to ensure the yarn strands are ready for the next round.
The trickiest part is getting started. However, I promise you, once you get it, it will click and making multiple will come much easier.
Other Multi-Tone Grannies