Flexible layered materials
In Photon you can combine several layers of materials and blend it together. There are Layers such as Diffuse", "Reflective", "Transparenet", Translucent" and many more, two dozent blend modes and up to 20 layers per material.
Using this system billions if natural or phanatsy materials can be created. And even though you have so many possibilities it is just as easy like Photoshop(R) layers.
The only limit is your creativity.
More about Photon's Material system...