I got a nice vintage hone a little while ago. I thought it was a thuringian while it was covered in grime and grunge, but lapping it soon revealed that it was not. It was very hard to lap - if anything, as hard as or a bit harder than a charnley forest hone. During lapping it gave off a milky white slurry, tinged with lime green.

Here are some pics of the hone - dry at first and then wet. For a colour reference, there is a grey 'celebrated thuringian water hone' at the top, the mystery hone in the middle, and a blue/grey vintage thuringian below it:











The pictures haven't really caught the colour - it is a drab green/grey, and it has a kind of ripple pattern, almost 3D, in the depth of the stone - couldn't quite catch that with the camera either. It is about 9 inches long an 1.25 inches wide. I have only done a few minor experiments with it, but it produces an amazing edge - highly polished and incredibly smooth. The feedback - for such a hard, glassy stone - is great: as you begin honing it feels buttery smooth, not glassy and hard at all, and as you proceed a massive suction becomes apparent. I have done about 100 laps after an 8k stone, stropped the razor and it passed the HHT like a champ - the hairs just fell away as they touched the blade.

The water seemed to thicken a bit after 50 laps or so - I'm not sure if it was a thin slurry or just metal, though. It seems a bit perverse that a hone that was so hard to lap should release a slurry. After honing the surface of the hone (lapped to 600 grit) had got quite glassy - to the point of reflecting things held near it like the light bulb filament above my honing station.

It does have certain qualities in common with the less colourful charnley forest hones I have used, but it is cut much thinner (0.5 inch) and more regular than any CF I have come across yet. Given the colour I was trying not to get my hopes up that it was a cutler's greenstone, but I have not been able to find a really good description of one, let alone pics, so I thought that someone here might be able to help - one way or the other!

Regards,
Neil