Gold-Silver-Bronze as 2-4 is pretty common any time you get a rank above like Platinum or Radiant, so just dropping Copper, though a little disappointing, would work well.

The UQP model of Sublime -> Triple Rad -> Double Rad -> Radiant is also an option, and though while funny is probably best saved for if we ever get category extensions.

Why are the rank medals: Radiant->Glass->Armor->Blue Paint? Wouldn't it make much more sense and look better for them to be Radiant->Gold->Silver->Bronze->Copper like in game?