Table 2 Recorded data for archeological shell-made Go stones

Lyu family tomb,

Lantian, Shaanxi³¹

Northern Song Dynasty

Flat Circle

175

2.1

0.5

Zheng Shaofang Tomb,

Yanshi, Henan³²

Tang Dynasty

Two-Sided

Convex Circle

30

1.5

0.5

Baoshan mural tomb No. 1,

Chifeng, Inner Mongolia³³

Liao Dynasty

one-Sided

Convex Circle

1

1.3

0.45