Ah ok 
Just so you know, they are not producing this product, it was custom-made specially for me. If I need another one, I will owe them something. Not mentioning the logistic PITA that you can face for buying one "little" thing from China. Now, if you need a 40 feet container of them... We can talk
I'm kidding... partially 
I understand, you keep repeating yourself. The stone was custom made for you. I don't understand why you can not tell me where you got your stone, you obviously don't want to tell me, thats cool. You want to keep your your stone source a secret. I won't ask again. I know not to go to you down the road for made in china products.
If i need a 40 feet container from china, then we can talk? I don't want to get into this topic. This approach does not work with me. To even start I need a sample, not interested.
Anyways, i found a very convenient solution.
Burnt clay brick - Thermal conductivity 0.4 to 0.7 W/m-k.
Saputo - Thermal Conductivity: 0.3-0.6 W/m-K.
This is what im looking for a Blackstone Pizza oven to do neapolitan bakes. I don't really even care any more. I'm going to keep my BS for NY pizza and buy a seperate oven for Neapolitan.