[bplein]

In my experience (limited with vintage subs), the bezel itself should appear to be a solid thick disk that has had grooves relieved into it, like a drill that went around and drilled out cylindrical sections. That is like your top A example.

The lower example looks like a thinner disc that has ridges applied to it: Notice how the grooves are not cylindrical, but rather are just pointy valleys between the ridges.

My modern GMTII-C has the "thicker disk with cylindrical recesses" type construction

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edited later

Looks like a trick of the light in your second photo... the bottom photo shows it to be the same construction as the other, but with cylinders closer together that allow the ridges to be more pointy, less flat topped.