Go Stones: Slate and Shell Go Stones - Size 34 Biconvex (9.6 mm) Genuine Slate and Shell Go stones Shell stones made from high quality Hainan shell (much better quality than the common Mexican shell) Japanese standard size Includes 181 black stones and 180 white stones Dimensions: 0.87 x 0.34 in (2.2 x 0.96 cm). Weight: 5.4 lb (2.5 kg).