The listing says it is supposed to be a Escher, but knowing nothing about German hones I don't know what it is. I've never seen one this rough, so I thought they were probably pretty hard. stones.
I know someone once posted that without papers/label, they are usually a Thuringian at best. I messaged them asking for better pics and they posted them today. Anyone able to identify it?

Antique Water Razor Blade Sharpening Stone 5 7 8" | eBay