White Jade is Jade manufactured from the plasm of ghosts in the Yellow Springs. It is used to manufacture Artifacts in the same way that soulforging is used in Stygia.
White Jade is made through a specific skill in the Way of the Artisan arcanos, and can only be created out of a wraith drained of all Willpower. Because the Yellow Springs uses White Jade so heavily, Yu Huang depends on the Conquered Territories and Feng Tu to provide raw materials for his conquests. Artifacts constructed from White Jade are less durable than artifacts constructed from True Jade, but it is far easier to acquire and therefore far cheaper.
Within White Jade, there are several grades based on the quality of the soul used to make the jade. Jade made from kuei-go is notably inferior, a factor which complicated Yu Huang's invasion of Stygia.