I see YMI market single convex Yunzi stones as "Size 3," or 5.7mm thick and 22mm in diameter. They apparently also once sold "Size 4" single convex Yunzi at 6mm tall and 22.5mm thick. They are no listed as out of stock.

Does anyone know about this size scale? Or about YMI selling "Size 4" stones?

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The Master said, To stuff oneself with food all day without worrying about anything, is difficult indeed! But what about weiqi players then? It is better to be one of them than to do nothing!

Give them a call. Great customer service, usually.

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David Bogie, Boise ID
I play go, I ride a recumbent, of course I use Macintosh.

My understanding regarding the single convex stones is that the size refers to the diameter, not the thickness as with double-convex ones. The larger stones (size 5?) are, as I recall, only really suitable for Chinese sized boards.

That makes a lot of sense, considering the advertised difference between Sizes 3 and 4 is only .3 mm in thickness (which I kind of wonder about anyway, as other sources advertise Size 3 Yunzi stones being 6 mm thick) but all of .5 mm in diameter.

I was hoping to find some thicker single convex Yunzi but perhaps there is no such thing?

Also - do you know a good vendor for Chinese boards (assuming you mean on with square line spacing)?

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The Master said, To stuff oneself with food all day without worrying about anything, is difficult indeed! But what about weiqi players then? It is better to be one of them than to do nothing!

I suspect that the process for making single convex yunzi basically involves dropping globs onto a flat surface and letting them cool, so you can't really make them thicker or thinner than the surface tension of the material allows.

I've never looked for a Chinese-style board, which is the square style you're thinking of, so I can't say who is a good vendor.

Right you are, and you can see them doing it in this video from the factory, at about 2:07
https://www.youtube.com/watch?v=rPdk6PbFbZk

...and from a wider angle at 4: 07.

The flat surface in question is recessed at the desired diameter and, one suspects, at least to some degree, depth. The depth could be increased to create a thicker stone. Is it the case that the Chinese simply do not care for thicker single convex stones? Along the same lines - I wonder how old Yunzi really is, how widespread it was used, and what other materials have been used in China for go stones.

In any case, I put the question about Size 4 single convex Yunzi stones to YMI and will repost their answer here.

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The Master said, To stuff oneself with food all day without worrying about anything, is difficult indeed! But what about weiqi players then? It is better to be one of them than to do nothing!

Manchu, cf. the Wikipedia article on Yunzi.

Regards, Tom

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“The only difference between me and a madman is that I’m not mad.” — Salvador Dali ★ Play a slooooow correspondence game with me on OGS?

YMI's speedy response:

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The Master said, To stuff oneself with food all day without worrying about anything, is difficult indeed! But what about weiqi players then? It is better to be one of them than to do nothing!

More from YMI:

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The Master said, To stuff oneself with food all day without worrying about anything, is difficult indeed! But what about weiqi players then? It is better to be one of them than to do nothing!