"Glass Eye" Mother of Pearl or "Gyokugan"

[Jake6500]

So back in November 2024 I made a thread about the first mid-high quality piece in my collection, a gimei "Shozui" piece. Whilst it is no longer the best piece in my entire collection I still use it as my profile picture on the forum to this day and the eye still fascinates me. Here's a link to the old thread for anyone curious: 

Recently as I was playing around with AI, I decided to use Gemini to see what it could tell me about the likely tradition of the piece or about the technique used for the eye and it pointed me in an interesting direction so I thought I'd make a thread about it. I uploaded some images and had an extensive back and forth with the AI:

 

 

Eye Closeup:

 

What the AI suggested is that the piece is likely either late Edo Hamano or Iwama school lineage with a gimei signature. Glass eye, mother of pearl, etc as many on this forum already know was a practice that mainly became popularised in the Bakumatsu Period. Based on the sort of "milky" opacity of the eye and the lack of colourful iridiscence reminiscent of crushed shell, the AI determined that the eye dome on this piece was most likely made from crushed stag horn using a technique known as Gyokugan.

 

Gyokugan is a technique that originated from Buddhist statue carving however in the Bakumatsu Period, it (as well as other interesting techniques like Mother of Pearl or using bone, ivory inspired by netsuke craftsmen, etc.) was used experimentally by masters such as Hamano Noriyuki III, Unno Shomin or Iwama Nobuyuki who sought to make their work feel more "realistic" or "alive".

 

The AI also provided some interesting information about the intricacies of using this technique (Gyokugan specifically...) on a small tosogu such as a kashira which appears to have been a very difficult process requiring precision. Here is a simplified outline, as I understood it:

 

1) The piece would need a carefully carved slot with a slightly raised rim in which the dome would be inserted.

2) Next, a properly fitted dome made of crushed stag horn would need to be shaped and slotted.

3) Taka-zogan would be shaped around the eye to give it its artistic appearance.

4) The artisan would also have to hit the metal around the dome tightly into place (seen in the brow here) to ensure that the piece retains its cohesiveness over time, as the stag horn material expands or contracts depending on hydration over the decades or centuries.

* For this reason, Tosogu pieces that retain their domes (and are not later Meiji productions that use adhesives) are quite rare.

5) Finally, an incredibly small hole would be cut into the dome and a tiny shakudo peg inserted, or alternatively black lacquer would be used to form the pupil in the dome.

________________________________________________________________________________________________________________________________________________________________________________________

All of this interesting information about Bakumatsu Period experimental pieces aside, I figured this thread would be a space to share examples of tosogu pieces featuring mother of pearl, inlaid stones, bone, ivory etc. Most of all whilst I have found some limited information about this technique, most of what I can find relates to Buddhist statue carving. If anybody is able to locate information or examples of the Gyokugan technique used in other tosogu pieces, I would be very grateful! 

 

(Dale Sensei, I am hoping you can throw me another bone!) Post some crazy Bakamatsu experimental works!

 

DISCLAIMER EDIT: Do also keep in mind that I am not 100% sure the eye is made using this technique. I am simply going off what the AI suggested... I just ran these images through ChatGPT which suggested Inlaid translucent stones like agate or chalcedony!! (This may however be ignoring the historical intricacies of Hamano style carving or Bakamatsu Period experimentation and going solely off the 100's of years dried out horn texture which looks rough like stone, so I think the Gemini assessment makes more sense. It's also a lot harder to hit soft-metal around precious stones without causing damage or breaking something!).

Edited April 15 by Jake6500

[Ray Singer]

The inlay does appear to be in glass, and I coincidentally received this piece below just a few hours ago. 

 

Best regards, 

Ray 

 

 

[ROKUJURO]

Hi Jake,

in my opinion, it is unlikely to be stag-horn which is a bone material, consisting mainly of calcium phosphate. If it is not some polished quartz, it is probably glass as Ray says. 

An expert may be able to polish it so PINOCCHIO would have clear view again! 

[Spartancrest]

Could the eye be a natural crystal or stone? There is also enamel as an option? 

    https://art.thewalters.org/object/51.1265.2/  Coral?

[ROKUJURO]

Dale,

the brown-red material is very likely coral, but it could also be red jasper or carnelian, just from the colour. But I don't know if these stones were available in Japan at that time.

Natural crystal is a kind of quartz (= silica/silicon dioxide, agate, amethyst, flint, Arkansas and Ouashita wetstones, and others).

You can create almost any colour with enamel, however, this will always be flat and, as far as I have seen in Japanese context, applied in a kind of metallic frame.

[Brian]

I would say almost certainly coral. (The fruits, not the eyes)

[Jake6500]

On 4/16/2026 at 5:50 AM, Ray Singer said:

The inlay does appear to be in glass, and I coincidentally received this piece below just a few hours ago. 

 

Best regards, 

Ray 

 

 

Thanks for sharing this example Ray, it is the closest I have seen to my own, though I think the material is probably still different. The middle picture makes the pupil underneath more visible which suggests it could have been produced using a similar method.

 

Dale, I don't think the eye on mine is made using a stone or enamel. The material is cloudy but see-through and the yellowish tint is likely the result of 150+ years of aging so I suspect it was originally even more more transparent. The metal appears to have been hammered over/around the dome to lock it into place which leads me to doubt the use of a stone as it would be hard to do this without breaking something. A thin organic material made more sense to me, mainly because the material would have more flex or yield. Glass seems plausible to me as it would be more pliable whilst in a heated state.

 

Quartz or a similar natural crystal seems possible as well but I think a lot less likely...

 

I've finally got round to ordering a Jewellers loupe to take a closer look at the eye and see if I can narrow down the material. Figured given how deep I've thrown myself into this hobby it'd be a worthwhile investment to assess the quality of pieces, investigate construction processes before submitting to shinsa, etc.

Edited April 17 by Jake6500

[ROKUJURO]

Jake,

of couse the metal is formed and finished BEFORE any organic or non-organic material is inserted!

In case the eye was formed from glass, there would be no aging or colouring (in human time). Natural crystal would also keep its original colour, however, both materials may well have a yellowish tint from the beginning. Also, in case the eye was set in with URUSHI or a pitch-like material, there might be an effect from that.

Glass in such small dimensions is not at all "pliable", so there will be no press-fit or similar.

KASHIRA and related shaped metal objects are mostly formed in a hollow/bowl-shaped steel mold, not on a "dome" shaped tool.

[Jake6500]

On 4/18/2026 at 1:05 AM, ROKUJURO said:

Jake,

of couse the metal is formed and finished BEFORE any organic or non-organic material is inserted!

In case the eye was formed from glass, there would be no aging or colouring (in human time). Natural crystal would also keep its original colour, however, both materials may well have a yellowish tint from the beginning. Also, in case the eye was set in with URUSHI or a pitch-like material, there might be an effect from that.

Glass in such small dimensions is not at all "pliable", so there will be no press-fit or similar.

KASHIRA and related shaped metal objects are mostly formed in a hollow/bowl-shaped steel mold, not on a "dome" shaped tool.

I did read that Edo Period glass often had a yellowish tint due to the manufacturing process at the time. Another thing I read is that Bakumatsu artists included a thin gold foil underneath to give the eye a more realistic look and this can degrade under the glass leading to a more cloudy appearance over time. This is what I was referring to when I mentioned the aging process. I definitely should have specified that and realise I was being a bit vague.

 

The pupil of the eye may or may not use urushi (I think it probably is but it is hard to tell for sure as it is underneath the eye dome).

 

> Glass in such small dimensions is not at all "pliable", so there will be no press-fit or similar.
Good point I hadn't properly thought through fully. 

 

> KASHIRA and related shaped metal objects are mostly formed in a hollow/bowl-shaped steel mold, not on a "dome" shaped tool.

 

Sorry Jean, but I'm not actually sure I understand what you're trying to say with this last bit... When I'm referring to a "dome" I'm not talking about the kashira itself but about the eye which I presume was constructed by inserting a hollow dome made of a see-through material (such as glass) into a pre-determined hollowed space (the eye socket). The pupil of the eye is quite clearly placed behind said dome, likely made of urushi as you suggested.

 

I was not suggesting the kashira itself was made on a "dome shaped tool" so I think this is a simple misunderstanding.

 

 

 

 

[ROKUJURO]

Jake,

glad we could get cleared some points! But:

.....Bakumatsu artists included a thin gold foil underneath to give the eye a more realistic look and this can degrade under the glass leading to a more cloudy appearance over time. This is what I was referring to when I mentioned the aging process.....

The thin gold foil provides indeed a more realistic look of a glass eye as the gold reflects light like a natural iris. BUT gold never degrades or ages or 'dissolves' in glass, so even after 1.000 years, it will still look the same. By the way, this technique is still used nowadays.

And to mention it again: the artificial eye will be set in 'cold' and completely finished, probably fixed with some kind of glue (URUSHI or pitch). 

[Jake6500]

20 hours ago, ROKUJURO said:

Jake,

glad we could get cleared some points! But:

.....Bakumatsu artists included a thin gold foil underneath to give the eye a more realistic look and this can degrade under the glass leading to a more cloudy appearance over time. This is what I was referring to when I mentioned the aging process.....

The thin gold foil provides indeed a more realistic look of a glass eye as the gold reflects light like a natural iris. BUT gold never degrades or ages or 'dissolves' in glass, so even after 1.000 years, it will still look the same. By the way, this technique is still used nowadays.

And to mention it again: the artificial eye will be set in 'cold' and completely finished, probably fixed with some kind of glue (URUSHI or pitch). 

I see, thanks for that information. Seems like my understanding of what I read was simply incomplete.

 

The Jewellers loupe I bought just arrived in the post today so I've had a quick look at the eye through it again, though I'm still getting used to using it...

There does appear to be an extremely small hole at the top of the eye which may have been used to inject black urushi to form the pupil at the back... The hole is so small that it is just barely noticeable with x30 magnification.

 

Here's a repost of the closeup photo of the eye with the area of the hole identified...

 

Based on the observation of a thin gap at the bottom of the eye between the sclera and the metal and the absence of such a gap at the top, Gemini is still pointing me toward the use of stag horn for the eye dome on the basis that it believes this slight gap is a result of shrinkage due to dehydration of the material... The lack of a similar gap at the top is likely because metal overlapping the top of the eye is holding the dome in place. 

 

This explanation makes sense to me but being skeptical of AI (which I'm using as an investigative tool rather than any sort of authority) I still don't feel confident one way or the other about whether the piece uses horn or glass...

 

None the less I feel like this investigative experiment has helped to develop my understanding of the piece and its construction, albeit to an incomplete extent.

Edited April 22 by Jake6500

[ROKUJURO]

Jake,

I certainly do not know all tricks the TOSOGU-SHI knew at that time, but I am fairly certain that we can exclude injection needles and syringes for the EDO era.  

However they succeeded to make an eye, looking very much life-like, we certainly have to admire the whole work, metal including.

[Matsunoki]

The most common material used for inlaid eyes in Japanese Art is translucent horn often with a darker pupil. Found on metalwork, netsuke, Shibayama, okimono etc.

This is what this eye looks like to me. I’ve made 100s of them!

Quick pick of something similar….

 

[Jake6500]

1 hour ago, Matsunoki said:

The most common material used for inlaid eyes in Japanese Art is translucent horn often with a darker pupil. Found on metalwork, netsuke, Shibayama, okimono etc.

This is what this eye looks like to me. I’ve made 100s of them!

Quick pick of something similar….

 

 

This is exactly what Gemini thinks this is...

 

The exact construction method is where it gets complex as there were a few ways this was done. Sometimes a metal "lip" was carved over the dome material to hold it in place (higher quality, more advanced construction), sometimes it was basically glued down with an adhesive (lower complexity construction). 

 

Having had a chance to look at the piece in hand with magnification, I am now leaning toward the former, more complex construction. 

 

Quote

I certainly do not know all tricks the TOSOGU-SHI knew at that time, but I am fairly certain that we can exclude injection needles and syringes for the EDO era.  

 

Jean, I was curious about this as well, however there seem to be a couple of possibilities for this including the use of a small birds feather quill or utilising a very fine, hollow bamboo needle as delivery devices and letting gravity do most of the work. A plunger could also be used in tandem with the bamboo needle to "inject" urushi, usually made of tightly rolled washi paper... These were apparently called "Kuda-fude" and were used in Maki-e to drop powders and liquids into precise spots, so it does appear to be a technical possibility. 

 

Remember, we are talking about a very late piece toward the very end  of the Edo Period, circa 1850-1860...

 

Apparently Henri Joly's 'The Sword and the Tsuba' has some further information about jewelled eyes and organic inlays in late Edo Hamano and Iwama school work, so my next goal will be to get my hands on a copy of this text.

 

EDIT: Here's an interesting and seemingly similar stylistic example I found in Joly's Catalogue of the Naunton collection... This seems to feature a similar, hyper-realistic eye in the same style as my Tengu! The brow and carving aroud the eye also seems very similar and was signed Jogetsusai Hiroyoshi (Uchikoshi school)

 

Another fuchi kashira which sounds borderline identical to mine in design is described in Joly as follows:

 

Edited April 22 by Jake6500

[Matsunoki]

There are 3 main ways of reliably creating the dark pupil.

1. a piece of black horn is inlaid into the front of the eye and then polished down…..most common. 90%+

2. a piece of dark horn is inlaid into the back of the eye….rarely done as the effect is not as crisp

3. a hollow is created on the back of the eye and filled with black lacquer or similar…quicker thus cheaper

 

A even cheaper method is simply to stain or lacquer the pupil onto the front of the eye but this obviously wears off very quickly when handled.

 

 They eye in question is either 2 or 3 above imo

 

I think we can discount any possibility of injections!

 

As for how they are securely fitted…..most are simply glued in with a variety of adhesives. Some have a deep tapered reverse to give greater surface area adhesion. 
 

Raising up a metal lip after insertion would likely damage the horn so that’s unlikely and I have never seen it done on organic material, only on other metal inlays
 

Just for info…..the horn used can be of varying transparency depending on the desired effect….from virtually clear to dark amber to black.

 

In addition to horn a variety of shell (mother of pearl) can be used for the eyes ……golden lip pearl, black lip pearl, bronze lip pearl etc …..all showing a range of stunning iridescent colours when finely polished. Often mistakenly described as “gem stones”. 

 

[Jake6500]

On 4/23/2026 at 5:24 PM, Matsunoki said:

There are 3 main ways of reliably creating the dark pupil.

1. a piece of black horn is inlaid into the front of the eye and then polished down…..most common. 90%+

2. a piece of dark horn is inlaid into the back of the eye….rarely done as the effect is not as crisp

3. a hollow is created on the back of the eye and filled with black lacquer or similar…quicker thus cheaper

 

A even cheaper method is simply to stain or lacquer the pupil onto the front of the eye but this obviously wears off very quickly when handled.

 

 They eye in question is either 2 or 3 above imo

 

I think we can discount any possibility of injections!

 

As for how they are securely fitted…..most are simply glued in with a variety of adhesives. Some have a deep tapered reverse to give greater surface area adhesion. 
 

Raising up a metal lip after insertion would likely damage the horn so that’s unlikely and I have never seen it done on organic material, only on other metal inlays
 

Just for info…..the horn used can be of varying transparency depending on the desired effect….from virtually clear to dark amber to black.

 

In addition to horn a variety of shell (mother of pearl) can be used for the eyes ……golden lip pearl, black lip pearl, bronze lip pearl etc …..all showing a range of stunning iridescent colours when finely polished. Often mistakenly described as “gem stones”. 

 

 

Thank you for this additional information Colin. 

 

I would assume based on the options you've presented that the third makes the most sense in this case, however this leaves me to wonder why the small, barely visible hole at the top of the eye is present. If it was not to drop urushi powder into, why is it there?

 

The eye lacks the iridescence of pearl so I think that material is unlikely on this particular kashira.

 

I would really love to get an image of Naunton collection 2828 to compare to my own piece and see if there's any connection but unfortunately the description was all I could find. Short of paying a gazillion dollars for one of the original 300 1912 prints and viewing the addenda I'll probably have to give up on that.

[Matsunoki]

3 hours ago, Jake6500 said:

however this leaves me to wonder why the small, barely visible hole at the top of the eye is present. If it was not to drop urushi powder into, why is it there?

Hi Jake,

I think the most likely explanation is that someone used a pin to see if it was glass…..and doubtless found out that it was not glass! My comments are based on having made a huge number of these eyes in a variety of materials when I used to restore pieces (netsuke, shibayama, okimono etc.) During that time I have never encountered a glass eye nor any where any type of pupil had been created by dribbling anything internally (except from the reverse as described above). 
Once you get the hang of it and have the right tooling they are not that difficult to make…..just a bit fiddly - which tends to mangle your fingernails (miniature diamond drills and cutting discs on flexi drive jewellers machines). 
 

[ROKUJURO]

3 hours ago, Jake6500 said:

....why the small, barely visible hole at the top of the eye is present. If it was not to drop urushi powder into.....

Jake, 

usually, URUSHI is liquid; it is natural lacquer.

[Jake6500]

12 minutes ago, Matsunoki said:

Hi Jake,

I think the most likely explanation is that someone used a pin to see if it was glass…..and doubtless found out that it was not glass! My comments are based on having made a huge number of these eyes in a variety of materials when I used to restore pieces (netsuke, shibayama, okimono etc.) During that time I have never encountered a glass eye nor any where any type of pupil had been created by dribbling anything internally (except from the reverse as described above). 
Once you get the hang of it and have the right tooling they are not that difficult to make…..just a bit fiddly - which tends to mangle your fingernails (miniature diamond drills and cutting discs on flexi drive jewellers machines). 
 

 

Quote

Jake, 

usually, URUSHI is liquid; it is natural lacquer.

 

Thanks guys, this explanation makes sense. I've seen a video about the use of this eye technique in larger statues. Setting the pupil from the back would certainly align with the practice as it exists today and make a lot more logistical sense.

 

I am still chasing down a picture of that kashira in the description I posted above... As it turns out the digital copy i was using ended up being a blended mash of Naunton and Behrens. If anyone reading has a copy of the W. L. Behren's Collection (Part 3) and could take a picture or scan of plate LXXIII (73) where I believe the potential sister kashira can be found, it would be much appreciated.