The lost wax (cire perdue) bronze casting technique is popular in Tibetan bronze images.
The stages of production are as follows:-

1) Wax Modeling:
The image is modeled in wax .This is done by specialized artisans as the stylistic and aesthetic form is the most crucial part of the art.

2) Casting Mould:
Layers of selected softness of clay mixed with charred husk, fabrics are coated to cover the whole wax figure leaving an opening for the pouring channel.  It may take an interval of couple of days for each layer of coating.

3) Casting:
When the clay mould is thoroughly dried under the shade, it is heated and the wax is melted out.
The hollow cavity of the fire-proof clay is filled up with molten metal. The mould is being broken off revealing the cast image.

4) Finishing:
The metal image is polished and engraved.

5) Gilding:
Melted gold mixed with mercury is applied to the surface of the sculpture.
When fired at 360 degrees centigrade, the mercury evaporates leaving the gold intact on the surface.
The richness of the shine depends on the number of layers and the fineness of gold.

Fire gilding seems to be limited in Nepal, Tibet and China, rarely in north India and almost never in Swat Valley, Kashmir and Western Tibet.1
The significance of the lost wax casting technique is mould cannot be re-used and only a single statue is yield making it a unique art.
  
1    p.40 Schroeder, Ulrich Von: Indo-Tibetan Bronzes Visual Dharma Publications Ltd. Hong Kong© 1981