In the "Bardo Thodol" (Tibetan Book of the Dead), Amoghasiddhi appears to represent the accomplishment of all action. His name means 'Infalliable Success" and his consort is the well-known Green Tara.
Amoghasiddhi is associated with the northern direction and the fourth skandha, mental formations. This can also be interpreted as impulses, which is strongly associated with action. Meditation on Amoghasiddhi Buddha vanquishes envy and jealousy, two often impulsive actions.
These statues have been gilded through a process of electric gold plating, which deposits a thin layer of gold upon the exterior with an electro-chemical process. The end result is absolutely stunning.
