^That sounds pretty much like how it'd be done.
Lemme touch up with a few of my thoughts:
- Your word, "grader"... that's pretty much been synonymous with Thorn for several months now :P
- There is one "order" requirement: you cannot get a high-level emerald of a color before the lower one. Therefore, the way I see it, you'd assign a 0 or 1 to each challenge for each player depending on it they finish it, and the awards displayed would be based on two things. If a zero appears in a color, it'd have to display the emerald lesser than it, even if you completed a later challenge in that color. And if the sum of the values is greater than or equal to 8, 16, or 24, the extra pics need to show.
- The Awards have to be connected to the forum somehow. Otherwise,t he Awards page just becomes another Storage Topic: you earn it, but nobody looks at it.