What are the Yoshinkai aikido belt colours?

Yoshinkai/Yoshinkan Aikido Belt colors can vary from Dojo to Dojo. In Japan, you are a white belt until you are a black belt. The color system is American/European, not Japanese. So there really is not a specific answer to your question. Each belt color represents a "Kyu" or "Dan" rank. A "Kyu" rank is any rank which is below a black belt. The first level of the black belt rank is Shodan, which is obviously a "Dan" rank. The color of the belt is no more than a way to identify your rank at your own Dojo, what is more important is your "Kyu" or "Dan" rank. For example, if you had a Green belt and you wore it to another Dojo, they may ask, "what rank are you?" because the Green belt does not tell them what rank you actually are.