OK what am I looking for?

I have given it a quick go over on 1200 grit wet & dry, I'm at work and that's what is to hand, and there is no real change. It may be that the black flecks are oil that had soaked in but that would require a coarser grit to get down deeper to see for sure. I can see further rusty red flecks and lines in addition to the reasonably clear one and the colour is on the grey side of olive green.

Whatever it is its now glassy smooth, so I will check its abilities out as a finisher. I will lap it properly when I get home, what's the best sequence of grits?