I was given a stone as a gift.

[Jessica de Boer]

My birthday is coming up and a good friend sent me this wonderful stone as a gift. He said it's an "Okudo tenjou suita". The bottom of the stone was uneven so he made it flat with epoxy. I glued it to a piece of Teak which I varnished beforehand and placed a small rubber foot on each corner so it doesn't move around. The glue was dry this morning so I gave it a test run and it's a very fine stone, it must be in the neighbourhood of at least 10.000 grit. And I love the finish, there's a very clear distinction between the soft and hard steel and the hard steel becomes very bright with this stone.

[ken hatch]

Jessica,

A good friend indeed. A beautiful stone and a beautiful finish on your chisel. A man made stone can be faster and give a high shine but nothing works like a natural.

ken

[Jessica de Boer]

A man made stone can be faster and give a high shine but nothing works like a natural.

I've been doing some reading on these natural stones from Japan and it's very interesting how they were formed and the way they work. Apparently these very fine stones also harden the edge through a combination of the generation of warmth (the steel rubbing against the stone) and how some minerals in the stone interact with the steel. It's all very fascinating.

[Vincent Tai]

I've been doing some reading on these natural stones from Japan and it's very interesting how they were formed and the way they work. Apparently these very fine stones also harden the edge through a combination of the generation of warmth (the steel rubbing against the stone) and how some minerals in the stone interact with the steel. It's all very fascinating.

A very good friend indeed! The Nashiji on that is very nice. This hardening effect thing, So says Kengo Usui proved it with a RC tester; it's on his main page of Japan Tool. I have no idea how he managed to RC test the tip and not penetrate and break it off. I hadn't the time myself to press So on this when he was a little less busy. The warmth and mineral interaction sounds interesting. Sounds almost like some sort of embrittlement process. Personally I have yet to decide if these stones really harden the steel more or not but I have enough skepticism to lean to one side. All I really know is I love mine and try to use them daily.

[Frederick Skelly]

Wonderful gift! That's a good and observant friend to realize you would value such a gift. Enjoy!

[Brian Holcombe]

They probably burnish the tip more so than harden it.

[brian zawatsky]

My opinion may not carry much weight in this arena, but from an empirical standpoint I have a really hard time believing that the stone has a hardening effect on the steel. This sounds a bit like something that people who sell natural sharpening stones might say. Or sorcery. Take your pick lol

No disrespect intended, JMO

[Jessica de Boer]

My friend who gave me the stone told me to make a sharpening slurry on the stone with my Atoma diamond plate. It's the same principle as making a slurry on a coticule with a small coticule rubbing stone. It results in faster sharpening but it doesn't become coarser which is the case with a coticule.

[Matt Lau]

NIce stone, and good friend!

[lowell holmes]

If I wanted such a stone, where should I look foe one?

[brian zawatsky]

If I wanted such a stone, where should I look foe one?

Hang on to your wallet, Lowell...

[Richard Jones]

I've never seen an okudo tenjou suita that color. Pretty rock, for sure. Happy birthday.

[Jessica de Boer]

If I wanted such a stone, where should I look foe one?

I don't know where he got this stone from but I know you can find loads of stones on Yahoo Japan Auctions. I bought some stuff from there in the past myself and I used Buyee, a proxy bidding service.

[Vincent Tai]

If I wanted such a stone, where should I look foe one?

Hi Lowell,

So from Japan tool is great. But he's one guy who goes through each request at a time and finds a few stones to fit your needs that you can choose from so he's swamped. Like backed up a quite few months swamped. Still worth a try IMHO. There are other sources, aframestokyo, etc come to mind. I have gotten one through Ebay before which actually turned out quite nice. That seller has now gotten their own site etc but I can't remember the name. I haven't used any other person then So and Ebay so I can't really recommend anyone.

I think the notion that a Jnat is expensive is perhaps brought on by the thicker and bigger ones that are what people usually see. Those can get astronomical in price as they grow in size. It will be hard for a hobbyist to wear through a more generically synthetic sized one.

Here is my usual finisher I got from So. A pretty good price, He thinks that natural finishing stones this size are more cost efficient then synthetics because they are thicker and harder so they last longer. Of course there may be drawbacks such as problems with modern alloys. For pure work efficiency then a synthetic will edge these out; but mixing in synthetics at the coarser end to medium range makes for efficient work. O1, PMV-11 hone up fine on this stone though. Of course I hollow grind, and use synthetics or spyderco etc before this stone for those sorts of steels. I think this stone is about 130 USD+, depends on how your currency is doing the day of purchase etc. Hones big irons just fine. Price in JPY and its dimensions are beneath the photos.
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183 x 66 x 27, 725g.15000JPY