EL (elbonator) tested a medium blue/grey NOS Thuringen (escher) for me and he already owns on of my Hunsrueck hones. His seems to feel they were very similar in grit but that the newer Hunsrueck was a much faster cutting stone. For him at least, the Hunsrueck was the one he liked better.

Supposedly the lighter and greenish stones are softer and maybe that makes them release the garnets into the slurry faster making them the "prefered" stone for some. I doubt any great difference will be seen though.

I've got a green/yellow Escher/Thurnigen marked Fox and a light blue NOS Thurnigen I'll send up to EL for testing as well. he has far more experience than I in this so will give a better trial than I could.

Tony