These are Clamshell White Go stones and Nachiguro Black Go stones with a 15mm diameter, which is about 30% smaller than a standard Go stone (diameter: 21.9mm).
The thickness of the 15mm-diameter Go stones is about the same as a standard size of No.32 in terms of the ratio of diameter to thickness.
We also have 15mm Go Stone sets and Miniature Go Bowls.
＞Go to 15mm Go stones set page
＞Go to miniature Go bowls page