Alan

They made plenty. Example:

Red

Banded opaque.

Crud from the cullet pile. Fire brick should be white.

x2

x3

New Vacor

That is my view.

I looked again. I don't see any sign of cane construction.

Respectfully, you're doing ID based on the outside of the marble (and it's obvious defects) instead of looking at the interior.

Machine made with a manufacturing defect. Look at the marble and not the surface defect.

Ach du lieber !

Another invented name.

The grooves are vertical, imparting a (roughly) horizontal motion.

I too do not see where this leads, given how crude and variable the manufacturing process was. From an Akro perspective, the process was also crude and variable, and for the same reasons. From the corkscrew focus - corkscrews would be quite variable because the spin was imparted by the grooves in the spinner cup. The blank spinner cups were provided to Akro as smooth graphite. The machine operators had to carve the grooves and this appears to have been done fairly crudely with a pen knife. The depth, width and style of those grooves were very variable, owing to each operator's personal approach and possibly how hurried they were. My two spinner cups are different. Also, spinner cups were wear components. A spinner cup with freshly-cut grooves will impart more spin than an older, well-worn cups with smooth or damaged grooves. The vintage marble making process was a crude variable process. Odd, random results should be expected. They don't usually trace back to some unusual process.

Not cullet. You can see the glass ingot shear point. Speculation: At that size - the ingot was too large for the rollers, spun off the too-small rollers half-cooled and finished cooling on the floor.

Possibly spun off the rollers and hit the floor.

Reverse image search will not lead to accurate marble identification.

No-one is trying to "change your mind".

I don't see any oxblood or handgathered marbles in those pics.

Not Akro glass. Not ringing my MK bell, unless they have something new.

As noted:

Bravo to you for using a grey card for exposure/WB!

Sunlight is often better. Make sure you are manually selecting focus on the marble itself - which also determines exposure. Artificial lights have their own varying color temperatures. Those temperatures add artificial color to the photo, or fail to bring out true colors.

Not a Raven for me.