Yeah the fineness in early or later is a mix bag either way I believe. It has more to do with the hardness of the stone I think and how burnished the stone is. As the denser this type of material is the finer it usually is. Also what was considered better back in the day I believe had more to do with speed than fineness. As for the cut yes it would be a later sourced cut stone from the looks. It sounds like what I see on my screen maybe a bit off. I see a lot of the Red/purple mixed with green making a lot of the other shades you describe. Which not having in hand I can only guess from looks. I would guess it is a later CF with a high lever of the red buried in it muting the green and altering the colors. To me it just looks like a really cool odd CF and the level to which it finishes also seems to align with that. What I can say, but not sure it matters with CF. Is the saw marks differ from the saw marks I have on my labeled Marples CF and oddly enough I have similar saw marks on a older rounded based driver extracted. The saw marks or more at an angle then straight up and down as seen on yours. Both of those stones are just as hard as the others though. My finest one maybe a the tiniest bit harder than the Marples I don't know, but it has years of steel across it which has made it a bit finer.
Ooh... got a picture of your Marples one? That sounds cool! I’ve seen pics of various GRs, but not a CF. They clearly knew their stuff in terms of sourcing top quality UK stones eh!