Jade huang is one of the six forms of jade used for the recruitment of the court, a little bit like the staff identification card of today.  Each form and its different material would represent a different grade in the court.  By the Shang dynasty, it is more of a decorative object worn over the chest as a pendant.

This necklace is made up of piece of a hetain jade (nephrite) huang, tied together in the fashion of the famous jade armor.