Vintage Suwabute Clam Go Stones Size22 made in Hyuga with Go Bowls Japan

This is typical condition for suwabute go stones. （See photos. 　● Thickness: White stone about 6.3～6.7mm (size22 ). 　● Material: clamshell from Japan（蛤）made in Hyuga City, Japan. 　　　　　　slate from Mie（那智黒）made in Hyuga City, Japan.