Pretty 21/32" Blue swirl

[marblemanvintagemarbles]

This one really looks awesome. For some reason I keep seeing a similar marble in my mind from an old post on here about alley agate marbles. 

[akroorka]

A bunch of companies made slag’s—this one is not Akro, MFC, CAC or Peltier imho—but just maybe a slag.
Slags are simply white with a colored transparent base glass that have no rhyme or reason in the construction.

All marbles have two cutline’s but these may be harder to tell just where they are.

The glass was not injected, just mixed together in the furnace and out the funnel through the shears and rounded by machinery of one sort or another.

The handmade ones used this same process--just by hand--no machine driven rollers for the most part

I appreciate all opinions and hope to see some more.
Marble—On!!
 

[The Nickel Guy]

I would have assumed it was a swirl, a common but pretty one as titled. I have a number of them in a few colors that look a lot like it.

[davesnothere]

I would have guessed swirl too. Pretty common nothing  distinguishing.