Curmudgeon? Settle down... I'm only poking.
I've bought a few high end meerschaum pipes from well known carvers, but I don't trust the grading on those. I've seen them marked or rated as all kinds of things, depending whom you buy from.
Diamond, genuine block, mined in Turkey (not Africa - Gasp!), "F", "A", 1, 2, 3 and on and on. The only half way reliable system I have is the carver/brand you buy from and the price you pay. And that's not reliable either, if you want to be truly objective.
I have a $400 meerschaum carved by a "master" with a small, but obvious imperfection if you know where to look. Hard to find, but not my idea of the highest grade of meerschaum if #1 Diamond Grade A+ FL is supposed to mean anything.
They just make it up, like so many other things in this weird world of pipes.
If there is an official grading system that has some kind of broad oversight, I'd like to see it. But I don't think there is, which is why you find so many interesting descriptions for what people are claiming to be genuine block meerschaum, which really, seems to be the only high end thing about meerschaum. After that, all of the letter, number, gemstone, and whatever other combination of grading looks like nonsense.
There is the difference between pressed meerschaum and block, but I'd doubt that most people could even tell the difference. They'll swear up and down that they can though. I've had a pressed meerschaum (that was advertised as pressed) absorb the water test just as quick as a block. It annoyed me at the time, but I've gotten over it by now.
If it smokes well, you have a nice meerschaum. My guess is that most of it is block anyway, unless you're spending $30.
You really pay for the carver or brand.