I need to redo my tutorial on seams/cutlines. It was accidentally deleted.
Now that I have a decent camera, I can take pics of seams myself.
The cutlines are important for marble identification. In your last picture, the probable cutlines start at about about 6 o'clock and 9 o'clock. Then they're pointing back into the photo.
At this point, I think it will probably be a Jabo or a late Vitro.