Lewis B

Ubu yet mumei? An interesting discussion here around the subject. https://www.militaria.co.za/nmb/topic/14981-ubu-and-mumei/#comments

The koshire (especially the ray skin saya) is very fine. This suggests the blade for which it was made is equally valuable. Being mumei and o-suriage I would assume its quite old (family blade?)

Looks to have a kirikomi on one side of the mune. Can't quite figure out if it has shintetsu along a section of the hada. But Tanobe sensei seems to like it.

That 47g solid gold habaki is worth almost $5K in scrap gold value alone.

Not sure if everyone will have access to the 2024 source paper linked by @AlexiG and the authors hypothesis regarding Utsuri and its appearance on Nihonto. So I will post a link here. While still conjecture on the part of the authors its good to see an hypothesis examined in detail with scientific data and for the paper (I assume) to be peer reviewed before publication. As to why its present I agree with others here who say that for the most part it was not by accident. Without access to metallurgical testing the early smiths would have known which blades stood up to a beating in battle and those that failed, merely from a visual examination. It wouldn't take many examples to make the connection that a blade with Utsuri was more resilient (which appears to be the case) and for Utsuri to be 'engineered' into the blade to recreate those favourable characteristics of durability as an evolution, over decades and centuries, into the swordmaking process. As to why the appearance of Utsuri diminished going into the Edo period, that could be related to a shift from a focus on durability to one of aesthetics ie jihada and hamon. Far easier to appreciate a beautiful hamon line than ethereal Utsuri clouds. Utsuri paper.pdf

Load onto a Google Drive folder (no file size limits) and post the link.

Yet it has TH papers. That surprises me.

The obvious things: the small hamachi distance, from where nakago ends and the Ha (edge), mentioned earlier and the motokasane measurement. In this example its 0.49 which is thin for Yamato Gokuden, suggesting the blade has seen many polishes. Higher rez image of the monouchi area

Its a long blade @71.4cm. I won't post the link as that is the perogative of the poster. But its clearly had many polishes and a lot of the activity is compromised. Basically its tired. I think I would be looking elsewhere for my first early Koto blade. The Senjuin FS here on NMB is a much better example IMHO.

A timely reminder to all those, like me, who like a blade exhibiting utsuri. Nefarious sellers out there praying on the appeal of this feature. https://www.facebook.com/photo/?fbid=2401552303244992&set=pcb.2401556073244615 https://www.facebook.com/photo/?fbid=2401552296578326&set=pcb.2401556073244615 A warning from Andrew Ickeringill " A warning to sword collectors... Please have a look at these pics taken from a Japanese auction site, when you look at this utsuri, what do you see? Have a good look and think about it before reading the below... This kind of utsuri was drawn to my attention a few years ago, a client had asked me to open a window on an old tachi. As soon as I saw the blade, I knew something was off... it had been acid etched (not unusual) but something else was going on with the utsuri. After a few minutes pondering I concluded that the utsuri was fake, but the owner wasn't convinced and still wanted a window opened. Sure enough, the window revealed the utsuri was completely artificial, it came right off and didn't return. I believe the sword pictured here has had the same treatment, it has no utsuri... well it might have some kind of utsuri underneath the artificial one, but I doubt it. I'm guessing it's been created using some kind of VERY strong chemical process, applied either very carefully with a cotton bud stick, or perhaps a stencil was used as a guide. I've been seeing this kind of "utsuri" quite a bit recently, mainly coming from the Japanese auction sites. It's a very cheeky deception that I imagine has fooled many people. So, how can I tell this is fake just from looking at pics? That's the hard part to explain, I'll do my best... For starters, how do you view utsuri? Similar to the way you view the hamon. Real utsuri generally can't be seen very well from the angle that you'd normally view the jigane from, which is from directly above. But the "utsuri" in these pics shows up very strong in the jigane pics. What about the shape/pattern of this "utsuri"? It seems there's a contrived shape and repetitive pattern. On a sword with this kind of gunome-ba, I'd expect real utsuri to mirror the hamon in a similar flow, the utsuri would rise where the hamon dips into valleys, and the utsuri would fall where the hamon peaks (this isn't always the case with real utusri, for example shirake-utsuri). But with this sword you can clearly see the pattern of the utsuri is often at odds with the flow of the hamon in a very unnatural way. Also, please note the granule-like/mottled texture of this "utsuri", it's a result of the acid and you don't see that effect in real utsuri. One more thing, look how defined this "utsuri" is, especially the area down towards the hamachi where they've tried to emulate a mizukage-like effect. It's so sharp and defined, like it's been painted on, well it basically has been! So, just beware of these Japanese auction sites and their swords, some are gimei, some are acid etched in the hamon and jigane, and some have completely artificial utsuri. I'm not saying don't buy from these sites, there are some good swords to be found there, but you need to be aware it's like navigating a minefield, please be cautious and don't get had! I wouldn't recommend buying anything from these sites unless it's at least papered Hozon level."

I certainly wouldn't equate the utsuri 'effect' created with modern steel with that seen on early Koto tamahagane blades so being more specific wrt to the type of utsuri will be beneficial for this discussion.

Very true. First time I came across the term 'Utsuri' was in relation to a honyaki chef knife I purchased 7 years ago. The maker had referred to this feature in his description for the W2 tool steel blade as an indicator of the perfect heat treatment conditions.

Price?

I think it can form with both particles. Nie-utsuri being nie based.

Markus Sesko has a nice essay on the subject. https://markussesko.com/2013/08/22/some-thoughts-on-utsuri/