When I was looking for a monte to buy I had always thought that Jewel Violet was the rarest but from talking to people and reading the posts on PF it seems that Ash black is the rarest by miles. (BTW In 8 months of looking for a monte to buy I only saw 2 for sale & one of them was a poor - overpriced example )
So settled for my large turbo lux..... One day I now fancy an Ash black monte, if I ever see one for sale at the right price?

Good list though Paul! - wish I had that much time on my hands in work.