Some object classes (such as armor and weapons) are split into
"subclasses" when sortloot applies an ordering (for armor, all helms,
then all gloves, then all boots, and so on). Give gem class subsets.
Simple (1) valueable gem, (2) worthless glass, (3) gray stone, (4) rock
would give away information; instead, factor in discovery state and use
(1) unseen gems and glass ("gem")
(2) seen but undiscovered gems and glass ("blue gem"),
(3) discovered gems ("sapphire"),
(4) discovered glass ("worthless pieced of blue glass"),
(5) unseen gray stones and rocks ("stone"),
(6) seen but undiscovered gray stones ("gray stone"),
(7) discovered gray stones ("touchstone"),
(8) seen rocks ("rock").
If everything happens to be identified, the simpler ordering happens
(via 3, 4, 7, and 8) because the other subsets will be empty.