Ginrin fascination

**RobF** · 08-01-2013

This is the third paper from Addadi et al on guanine crystals in koi skin. In the first they SEM image iridophores and through spectroscopy determined that the guanine crystal platelets in koi iridophores were anhydrous guanine. In the second paper they more exactly sized the measurements of the crystal stacks and cytoplasm in-between. In the third paper they describe the amorphous substance from which the crystals form and discuss how the individual platelets grow flat contrary to their usual habit. There are some electron microscope close-ups of gin rin. A fourth paper is promised, but may not be immediately forthcoming, it will look at metallic iridophores. This would be an important extension of the previous research. And it would go a long way toward eliminating the ambiguity that the selection of specimens introduces. They used ogon and gin rin ogon and this introduces some uncertainty as to the micrographs being of gin rin or hikarimono. If a fourth paper deals with this issue then the selection of ogon and gin rin ogon was actually quite astute.

http://departments.agri.huji.ac.il/animal/staff/faculty_staff/sivan_berta/publications/40-Gur-etal-2012.pdf

**RobF** · 11-18-2013

I don’t know where this photo of the shoulder of a ginrin showa came from, I copied it from somewhere in July 2009. It is one of the better ones and I post it to see what better eyes than mine can see in it.

One thing I think it illustrates is the difference between silver (gin) ginrin and gold (kin) ginrin. Kinginrin appears only in the beni and ginginrin appears in the shiroji and sumi. Hiroshima ginrin is a layer of light reflecting cells, iridophores, immediately below the transparent scale. In koi this reflected light appears silver except when it is filtered by a thin layer of color cells located atop the scale (but below the epidermis) and then is golden (kin). Over the sumi there is ginginrin and where the sumi is atop the scale this shine can be blocked. The ginginrin that can be seen above the deep beni is the exception that proves the rule.

**dick benbow** · 11-18-2013

never was a fan of the fish with "bling". Too gaudy for me. I do truely like the pearl scale type as subtle and more refined. I have a sanke and bekko with this type right now in my pond. In all the years in the hobby, my first ones added just this year.

**ricshaw** · 11-18-2013

The following is from Russell Peters' Ojiya / Isawa Bound PSKoi - Fall 2013;

**MikeM** · 11-18-2013

Rob: I believe your explanation is exactly right. It's all about how the eye perceives the reflection of light.

Dick: Agreed... except I've not seen pearl Gin endure as the koi grows large. That said, I have seen photos and video of a few GinRin Kohaku that I'd make an exception simply because the gin was so evenly distributed on every scale that the impact was very strong. However, even these were under 65cm. One thing that bothers my eye is the Gin is often weak (or non-existent) on the scales along the spine from the back of the head to the dorsal. This trait really detracts for me. The head and shoulder are what gives 'personality' to the koi. When the Gin is weak immediately behind the head, I just keep focusing on that weakness.

**RobF** · 11-19-2013

Ricshaw: It was whiles saving those pictures of Russell’s sanke that I remembered the showa photo I posted, the play of color is endless. The ginrin on this fish shows two more aspects of ginrin. The first observation is that although ginrin is by definition seen in the first 2 or 3 rows scales along the dorsal line, ginrin does not appear on the dorsal line itself. And the second is when ginrin is viewed from increasingly oblique angles blue starts to dominate. Of course much of the blue in this photo, especially the more ventral, is a reflection of the tub, but the reflections higher up are less so.

This is one of Sangreal’s photos, the points raised above are also illustrated in this excellent photo.