Just got this yesterday. It is now the most beautiful stone I own. It's unbelievable in person, the pictures don't do it justice. The lines are striking and the overall coloring is really something else.
I've been told it's somewhere between 6-10k, but I haven't used it yet. Will wait for the weekend to give it a shot...I don't have any non-shave ready blades so I'll dull one just to check it out.