Wolfpack34 no need for apologies at all your question is very common. It is answer that i think was wrong.
I have seen some Tenjyou stones that was harder then Aisa or Namito and other way around, thats why i think it will be confusing for some to say that all Namito layer is harder then other layer ! To rait fines i aslo think is very unnecessary cose it is proved that all Jnats are same fines, only hardnes can vary