FYI, petrographical in my first post should have read petrological, too many late nights, too little sleep.

For those who say their Roll's Razor Hones are grey, the stones coming from the Whittle Hill quarry did tend towards a grey colouration, it was an inferior type of Charnley hone, more readily available in the late 1800's/ early 1900's, that tended to have green colouring.

Regards,
Alex