I can't speak much for Aboriginal techniques, but the primitive
methods don't change much.
You use loose abrasives and a variety of tools to carry them. I've
gotten surprisingly fast results with bamboo skewers, copper and
brass wire, and other such items. Try _On Divers Arts_ (ISBN
0-486-23784-2) for a good description of 12th century European
lapidary work. (Just ignore the bit about the goat blood). You
would be amazed at how much material can be removed with a leather
thong charged with a fairly coarse grit.
On Divers Arts: The Foremost Medieval Treatise on Painting,
Glassmaking, and Metalwork
By Called Also Rugerus. Theophilus
Manufacturer : Dover Publications
Release data : 01 June, 1979
Ron Charlotte -- Gainesville, FL
@Ron_Charlotte1 OR email@example.com