Collection-- valuable vs low value

[ShellSurfer]

I found this helpful as well. One reason I never purchase shells unless they are in a lot, or look unusual is because I never see really clean high grade shells. And never unusual large shells. (Funny I live a 10 minute drive from the Chesapeake Bay)
I have also noted that many higher quality shells that are selling are closer to 3 inches in length. Some smaller, but many are in the 80-120MM Range.