Gem — Perfect quality specimen that’s in the naked eye only.
F+++/Gem — Minimal imperfection sometimes unnoticeable mark and can be gem to mostly.
F++/F+++ — Has blemish, but doesn’t detract the beauty of the shell.
F+/F++ — Has obvious flaw, but still very collectable.
Fine — Less likely to be offered unless for a very special reason.
Dead – Dead or fresh dead collected.
N/R – Niger or Rostrated or both.