Thanks for your reply!
There were a variety of methods at a variety of times, and you are correct. Tsiens paper (as well as another I put a link to earlier here) listed various methods, although simple were effective. It also appears the Liangzhu may well have sometimes gathered diamond powder or ultra hard particles from alluvial deposits (like silt) and 'panned' for it (as a gold miner does) by using animal skin. This could cut down jade to ultra fine polishes, and the infered evidence for this being used in some cases is strong.
As for the length of time, the father to son carving jade story is repeated for the pre-historic jade carving industry of the Maori too, but I reasonably would put it at weeks to produce an item. Longer fine art works might require huge periods of time of course but when an industry and skill base is effecient I would anticipate sites that produced these items as a speciality and in numbers. These will be the Chinese equivalent I have found in NZ of stone working/industrial areas, and I have a number of ancient jade & calcite 'cores as well as 'pre-forms & 'blanks' of unfinshed Dong Son jades I will post soon.
The fact these have turned up provides some insight into the industry, and suggests people have found workshop sites where jades were made.
Early settlers noted that Maori in quiet times might pull out a jade and rub it on a stone while they talk, but the length of time by simple abrasion does not need to be years.
I know of archeaologists in NZ who made perfect stone adzes in the traditonal way (and length of time is something I pondered when I began to find stone workshops and fragments or whole adzes during my fieldwrk) and he can work, flake, fine polish and haft and stone adze in 2 days and then chop down a tree with it!.
The tools worked well, and the investment was not for a tool for the grandchildren (or a bangle in this case), although I have heard that 'generations of work' idea before I dont believe it will be born out by any real test.
I just found this thread and I have enjoyed reading it. I have reasons to doubt that diamonds or diamond dust were used by Chinese to polish jades, but that is another story.
I believe these jades may be older Neolithic Jade Cultures co;;ected from tombs from as early as the Liangzhu or dawenko Cultures. Like other Neolithic nephrite carvings found in the collections of the early dynasties were probably taken from older tombs.
I am interested in the origin of the nephrite from which the carvings were made. I have over the years don some work in the unique nature of the chemical composition and impurities different nephrite deposits. It appears that these properties may be unique and that there are none destructive tests that may reveal the origin of the stone. The primary early source of Neolithic nephrite was a mountain west of Shanhai. Nephrite from Xinjiang is reported to have been traded and used in eastern China as early as 4000 years ago. there are also soures of small deposits in central China, and there is a small deposit near the Bwoenite/Serpentine Deposits in Liaoning Provicne. Recently there is reported Neolithic use of nephrite from northern Heilongjiang Province.