Most of Shang Jades are of this type;where a sliced flat piece of Jade is  also incised on both sides.Note the following:

01.This is of a bird: a Crane.

02.The Jade is of high quality as it is translucent.

03.Using incised carving technique to give the impression of raised lines. Typical of Shang Jade.

Good example for evaluation of Shang Jade Technology.

 10th.May'08

Another example of this Jade Crane of the Shang Dynasty can be found in this excellent Jade Reference 

Jade Carving in Chinese Archaeology Vol.One

Yeung Kin-Fong
The Chinese University Press (Hong Kong)
Plate XIV:10 Crane

Unearthed in 1976 from Tomb of Lady Hao at Yinxu,Anyang,Henan.