That looks great, Numidan! The only thing that sprung to mind was how strike weakness could be factored into the equation? Superb idea though, which for the main part could work! At the end of the day a grade's a grade! Bag marks, edge knocks, etc, only affect appeal, and consequently value! Would be a very good start to get the grade right! I'm still trying to work out what the diagrams are of I'm assuming of something that someone could use in grading terms. -5 being good and -50 poor etc. I thought Derek Riley brought out a book for such requirements? Grading is always going to be subjective, no matter how we all think, we've seen it so MANNNNNNY times on this forum where we as experienced collectors do not agree, so we should basically pass that subject by and work on the rest.