I rec’d this as a gift but unsure what it is, or if it’s good enough for razors. I believe previous owner said it was an hard shoobadani (spelling?) and would need to use slurry stones to get anywhere. The bigger stone is maybe a little more blueish-grey in person, about 7”x2.5”. Looks like some inclusions may have been removed and not sure, but looks like faint remnants of a stamp. Any of you more experienced guys have any insights?