I have tested and used these ultra-fine finishing stones. The small brown paddle hone is used the most. Only “good” razors can be used on this stone. This type of stone can be stamped on the side fine, very fine, extra fine or extra extra fine..

The brown stone that has the blue inclusions behaves similar to a thuringian but is a harder finer stone. This is why you can use oil. It is probably from the Vosges mountain region too.
MIke