Jim M - There IS only one reason for the seam behind the skull, and that is for sizing. This is true whether the ring is made as a circle or made flat. If it started as a circle, the circle was simply cut, both ends were filed to make them shorter, then pressed together, and soldered. If starting out as a flat bar, the band was most likely fed through a machine which bends it circular, and then it was soldered. Regardless how it started, the final EXACT sizing was hand filed, and placed over a sizing mandrel before soldering.
