I don't know about seconds, honestly. I suspect that, when grown for pipes (they use a sort of block or mold to form them) the results are relatively uniform and nearly all end up useable. Pioneer had a script "P" stamp used on some stems, but I've never personally seen a stamped Pioneer calabash, and I believe they just weren't. When new, some Pioneers came with a hang tag identifying them, reading "Genuine block meerschaum by Pioneer."
I've seen more variance in size (but not shape) in the Austrian calabashes by Strambach, which were sometimes flared like trumpets, sometimes narrower, and ranged from medium to huge. Now, antique ones, I've seen everything from the deep U-shapes to horn/oliphant shapes (I have one of those).
I've seen more variance in size (but not shape) in the Austrian calabashes by Strambach, which were sometimes flared like trumpets, sometimes narrower, and ranged from medium to huge. Now, antique ones, I've seen everything from the deep U-shapes to horn/oliphant shapes (I have one of those).