Multiple materials in particle system

I am trying to apply multiple materials to a mesh renderer in my particle system but I cannot figure out how to do so.

I have provided a link to 4 images, the first 2 are an example of the particle system in action and the final two are what I am trying to accomplish. I am rendering the same mesh object but am only given the option for 1 material.

https://imgur.com/a/ZNBuHIQ

 

A texture for the poker chip seems more suitable, especially when you want to have many instances. No need to do this with colored polygons, you can then just use a basic disc.
Vertex colors (and a shader using them) would be an alternative if this is necessary for some reason.