I'm a bit busy now so I do not much time to play around. I think that at such magnification (x900) on any, even polished surface you will see some kind of defects.
About story of cast heads on TK rings. If there really are such signsin the eyes this can be result of soldering, as head will get most of heat during soldering. I have noticed that often when soldering head is close to melting temp, because I need to place it in correct position, I keep flame on it longer time, sometimes I need to resolder it because it is not straight. And it is very easy to overheat, just matter of seconds. Not often but there are cases when I need to replace head just because it is overheated and semi melted. And there you go, it looks like cast. Arround forehead and other outside surfaces I can go with sandpaper and grind off all defects, inside eyes - I do not care. Results are the same - inside eyes there are signs similar to casting signs
Same with band.
During TR and long after main soldering tool was gasoline/benzin burner. Instead of today's main gas burner it has much sharper flame and burns at higher temp. So at that time it was easier/faster to overheat piece during soldering.
About rest of discussion. You know that germans did not use lost wax method during TR for massproduced items. Reason is simple - lost wax method as we know it today, good for massproduction was developed for dental technicians only after war in 1950ies 1960ies, in jewelry industry it came AFTER. Otto Gahrs production all is die struck or hand made from scratch. I do not know about single piece made by him that would be cast.
Besides that there is manufacturing logic/practicability, that's in long version - we already went thru this ten years ago. If interested and thread is still alive there is much more.
There are less original rings than you think, much less...
