How do Chinese, Japanese, and Korean boards compare in sizes?

I bought these stones: http://www.amazon.com/dp/B0053NT00U/ref ... s_sce_dp_1

It said in the description that they should fit all boards, but they don't fit the old board that I had bought from Kiseido or Samarkand back in the day. So, I assumed they shipped me Chinese stones (since the description of size 5 Chinese stones says that they will fit only Chinese and Korean, but not Japanese board). Although these stones fit my shin-kaya board perfectly.

Tonight I was playing with someone from China and noticed that his stones are smaller than mine. He told me that Chinese stones are the smallest of all.

I am somewhat confused. Does the "not fitting" mean that the Chinese stones are too small for Japanese boards, not too big? But the dimensions on YM Imports are bigger for the "fit only Chinese/Korean boards" stones.

(I also noticed that the smaller Chinese-sized stones are easier to place on the board.)

Chinese stones are generally thinner with larger diameter.

Everything I've read says Chinese stone diameter and boards are generally larger than Japanese and Korean equipment. In addition, Chinese stones are single convex, which I believe would necessitate a very slightly larger board than double convex due to double convex's ability to overlap by tilting.

Size 5 (23mm) single convex are a large-ish diameter, comparatively. Most Japanese and Korean equipment is 20-22mm very roughly speaking.

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Right, I am talking only about the diameter, not the shape. I.e., the stones that I linked to (which are single-convex) are larger than the Chinese (single-convex) stones that my friend has bought in China. Both are yunzi.

At the same time, my stones (that I linked to) fit the shin-kaya board that I bought from YM Imports, but don't fit an old cheap cardboard/pressed wood board that I had bought a while back from Samarkand (which most glass stones fit). I assume it's possible they shipped me Chinese size by mistake (which is ok, as long as they fit my current board), but then why are these stones larger in diameter than my Chinese friend's stones? Perhaps there is a variability in diameter among Chinese yunzi stones. Or, I guess, maybe he bought Japanese-sized stones online, but it looks like they fit his bamboo board quite well.

There is another Chinese player in our club, and I think he stones (which he bought on his recent trip to China) are the same, smaller, size.

I bought my single convex yunzi in Japan and they fit a standard Japanese board. Any chance you got that size stone?

Well, is there any reason they wouldn't fit a Korean or a Chinese board? They definitely don't fit the board that I had bought a while ago.