Columbia Razor Stone?

I was going through some of my sharpening tools today and I found an older sharpening stone that was given to me some time ago. It is definitely a razor stone and it has the name "COLUMBIA" imprinted at the top of the stone.

I do know that there was a company by that name that either made or marketed straight razors but I've never really heard anything about them that stood out.

This stone is charcoal, dark gray in color and it is very smooth as far as stones go. Just wondering if this is a good find? Any information on it would be appreciated.

try test it and see how it acts. GL