They look exactly the same and shave the same. I haven't tested them with microscopes or other methods. I can't afford HAD and paying for testing each stone. Hardness, the slurry color, shaving with slurry, then with water, and finally with oil (with oil it feels very nice). Each stone has different feeling, and those two I have, feel and look the same. Of course there is a possibility that they could be different stones, but for now, I think they are the same.