u/JapaneseChef456

New arrivals. 5 decent sized stones, of which 3 were with their original package, so I knew what I’d get. These are the black Aoto, fairly soft, the Wakayama Ōmura (grey, black dots, sandstone) and the old mine Ikarashi (turquoise grey) with new mine Ikarashi being white with grey and brown dots.
Of the unknown stones, the second was broken. Colour, pattern, shape and slurry point to the fairly rare Shidomae from Yamagata. As it broke further during transport, I’ve even got a Tomo Nagura.
The last, mounted onto a worm ridden wooden dai reminded me of Iyo Ginboshi, but didn’t smell of it.
Searching through my picture library revealed similarities with Numata Gozôto. Unfortunately these stones stopped being mined before the wide use of circular saws, which was used on this one. The next similar stone was Numata Idomae. Similar pattern and colour, plus these were the last Numata stones that were mined, with circular saws being the norm. And these were pretty common, so finding it in a whetstone lot would not be a surprise. Last thing to do would compare with my labelled Idomae, a white, Kama size.

Got a new parcel with a couple of stones from Japan. Bid on two sets, one of which had a photo showing this stone, from a similar position. My initial thought: Tajima! The grey stone with white and black dots are the typical markers. This one here is hand sawn, so older, which does point to the Tajima mine in Hyôgo, that was closed in 1927 after a lethal accident. Other mines with similar patterns, all from Hyôgo prefecture are Moroyose 諸寄, opened after Tajima, often darker grey base, Sayo 佐用, rare, lighter grey base, and Asakura 朝倉, of which I've only seen a single example, so I wouldn't give a tendency of how this one behaves. So out with the diamond plate, and yes, the initial flattening exposes the Tajima and lookalikes pattern. Due to the hand saw marks, I'd say 90% Tajima. Original weight is 1339 g, hopefully I won't lose too much, giving this a flat surface.

One huge drawback when buying stones through the internet where the no identification is given, just photos, is the need to do detective work yourself, to try and identify the origin.

In this case, my first guess was Kaisei, the Yamagata stone used in Katana polishing progressions, after it replaced the Jôkyôji stone from Fukui, when these became rare. Well, nowadays Kaisei have become rare as well. And they come in three colours. Grey/blue, yellow/white and red/brown. So my thought when deciding to buy this 2.1kg chunk was Kaisei. It is a chiselled/hand hewn stone, which would also fit in with the Kaisei timeline, where the blue stones ran out first, so this might have been one of the last blue ones, with some red on the side. But when I actually I got this into my hands, a new line opened up, this time not from visual but nasal characteristics. A light sulfur smell when sharpening a knife on it. Not as strong as with other, white Iyo stones that I own, but the same smell, nonetheless, with some Iyo Honboshi having a blueish grey hue to them. Also this was a light soaker, initial water application was quickly adsorbed, after a third, generous splashing, finally the surface staid wet.

A quick run to the cellar for my other Kaisei stones plus a Niiyama/Shinzan, that was a short lived mining operation close to the original Kaisei mine, that was supposed to replace the old Kaisei, but of which not many examples can be found, probably because all that I've seen are the small scythe/Kama type.

Visual check with my blue (both have a break line going through them, seems to be a characteristic), these could be brothers. The small one shares the soaker characteristics too, but not the sulphur smell.

Reddish stone was solds as a maybe Kaisei, which the whetstone collector bought from a guy in Kumamoto, so could be some kind of Binsui/Amakusa too. Doesn't share the smell, isn't a soaker.

The small Niiyama/Shinzan, gotten in a small lot with one stone still having the original label, could probably pose as an Aizu from colour and pattern. But it has also this light sulfur smell, something that I haven't encountered with Aizu, yet.

Feeling tempted to use my diamond plate on the bottom side, to check out the brown Kaisei. My only fear is that it is the brown side, that keeps the stone whole.

All in all, the 90% Kaisei is quite hard, hardly any slurry on my Kurouchi Ōsaka style Unagisaki, and quite fine, maybe 3-4K after using my diamond nagura... This stone was likely even bigger before, with the further end having broken off at one point.