>GEM=precise data (locality and habitat) and very reliable (personally
>collected or from source which can be trusted)
>F+=as GEM, but may lack some details on habitat, very reliable
>F=as F+, but source, despite deserves trust, has not been checked
>Good=Usually only locality given, source reliabilty not checked
>Poor=data may be limited to country of origin, if more information is
>provided source is not supposed to be reliable
>
>GEM does not mean I know water salinity and temperature, but that standard
>habitat data are available such as depth, bottom, associations with any
>other sea life if present.

Personally, I think a scale of 1-5 or 1-10 would be better, but as
with dealers' specimen grading, it's only as good as the assessor's
competence or honesty. I also think shell quality should be graded by
number, as the accepted terms are nonsense.
--
Andrew Grebneff
165 Evans St, Dunedin 9001, New Zealand
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Seashell, Macintosh, VW/Toyota van nut