How The Gem Industry Works:

Finger-sized pieces of manufactured, or raw, stones are sold to the local mudalali. Laborers cut the raw material into several smaller pieces and then the stones are ready for shaping.
Generally, one set of laborers uses fire to weld the gem to a 10-inch pole coated with a wood paste. This makes it easier to control the stone. Another set of laborers forms the stones into a variety of shapes and adds faces to the stones. This can be done manually or with a machine.
Once shaped, the stones are given to other laborers to polish.
The stones remain on sticks to help protect the laborers' hands and to provide greater control of the stone. Laborers must polish every face of the gem, often needing a magnifying glass for smaller gems. The average worker produces 100 stones a day. 
The mudalalis then transfer the finished product to the marketplace, either directly or by an agent.

Source: Trichy Gem Industry Market Report, Heidi Boutros, University of Texas undergraduate.