We've learned about four of the ancient Chinese Six Ritual Jades:
Cong - earth, Bi - sky/heaven, Huang - North, Hu - West,
and Gui - East.
The last of the Six Ritual Jades was the Zhang.
This was a flat blade or axe, and it was used to mean "South".
(from: wikipedia - chinese jade)
Kid Facts - Blast from the past: Gates of Paradise