Many people have either seen or heard of the lost wax casting process. A very simplified explanation of the process is as follows:
A model or prototype of the piece of jewelry is made of wax or it can be another burnable material.
The wax model is then encased in a container and the container is filled with a heat resistant plaster.
The container is put in a kiln or furnace for four to five hours up to 1,200° F which causes the wax to melt and burn out. What's left is a hollow negative where the wax evaporated.
Molten gold or other metal is then poured into the cavity and takes the form.
The whole unit is left to cool and then emersed in water to dissolve the plaster.
What emerges is the rough piece of jewelry which is then be cut free of the pouring channel and filed, sanded, polished and set with stones.
The Egyptians were the first to develop this method in about the 1500 B.C. Since then it has evolved into a highly refined process that is used for more than half of the jewelry that is made today.