I have a Sorensen stone that was my grandfathers and I'm trying to determine the Grit. On the same side where the name is on the stone at the other end it's marked FINE. My confusion is that it feels more smooth to the touch than my 4000 and 8000 grit stones. I've found limited information on the Sorensen & Co stones to help me. The physical appearance is a light to medium grey and the stone measures 12" x 3" x 1/2". Any help locating information is much appreciated. Thank you in advance.