Actually, my introduction to heraldry (believe it or not) was one of the supplements for Harn (back in the '80s) - the Harndex (Harn Index) was a periodical that touched on different aspects of the Harn setting. One issue was mostly on heraldry, which I studied in depth, and turned out was based on real-world heraldry and covered the subject well. I had this product while in the US Army stationed in Alaska. Almost at the same time, I was a member of the SCA (Society for Creative Anachronism) - you know the guys who dress up in armor at the state fairs and swing at each other with rattan bats... Anyway, every SCA member can apply for a heraldic device to be assigned to his character (which conforms to the rules of most national heraldic associations, also the design needs to be original and not comparable to a real heraldic device.) It turned out that the rules knowledge from the Harn product was more in depth than the SCA's own heraldic rules. Many colors were not included in the SCA rules that were in the Harn rules.

Also of course my more recent studies on feudal Japan revealed the specific rules for Japanese kammon, or house crests which while having the same purpose as European heraldry, is also a completely different animal.