"The Legendary Go Stones"
The Specialty of Hyuga City - Clamshell Go Stones
The Go stones made from Suwabute clamshells, a unique species used to grow on Okuragahama seashore, are the specialty of Hyuga City in Miyazaki. However, Suwabute clamshells have been depleted since about 1990 and becoming increasingly scarce, which is why the Go stones made from them are called "The Legendary Go Stones"
Okuragahama beach, located in Hyuga City, Miyazaki Prefecture,is the place of origin of the World's only Suwabute clamshells. Its shells are said to grow thicker and thicker in order to protect themselves from the impact of rough waves.
In the past, the clamshells were cut into quadrilateral shapes and then cut into rounds one by one by hand.
Nowadays, we use a special drill-cutting tool to hollow out the clam into several round shapes.
Afterward, the two sides of the stone are rounded, a process known as "Menzuri".
Ultimately, each stone is polished and shaped by hands, and this is called "Tezuri", a vital technique to make traditional Hyuga's clamshell Go stones up to now.
There are two traditional tools in the process of "Tezuri", a shell stick and the whetstone with grooves. The craftsman uses the former tool as a holder to fix the clamshell stone on the whetstone, which corresponds to the Go stone's roundness, and begins to shape and polish it by hand.
The depth of the grooves of the whetstone are adjusted according to the number of clamshell stone.
Even if the thickness of Go stones is changed, the consistency of each shape must be maintained. Therefore, accomplished and delicate techniques are essential.
As the clamshell stone is polished, the depth of the groove changes, so the craftsman must adjust the whetstone several times during the whole set of Go stones is being polished.
There are two types of whetstones: one for polishing the stone's surfaces and the other for polishing the side of the stone circumference.