The jade used in ancient China was very different from the jewelry jade that we see commonly today, the brilliantly green jadeite mostly originating from Burma. The Chinese jades are mainly based on the mineral nephrite, more subdued in colouring and softer to the touch. Its crystaline structure, developed under heat and pressure over time, has densely interlinked cells which do not break apart easily. This solidity allows jade to be polished to a smooth and shiny surface not readily damaged by contact with even hard objects and corrosive agents, thus allowing them to survive many centuries of burial in soil for modern rediscovery.
While the burial of jade objects in the tombs of tribal chiefs and shrine priests indicates their ritualistic functions, as symbols of personal status and divine duties, we are less able to guess whether other kinds of jade objects also existed in more general aspects of neolithic life. It is likely that initially jade was simply used to make tools like other rocks, but gradually its ability to be ground and polished into thin and sharp blades caused more weapons to be made from jade. Because of the importance of weapons as tokens of power, jade objects began to take on a symbolic significance. Its attractive appearance would also make it the natural choice for ceremonial purposes, gradually evolving into heavy ritualistic use.
Whereas pottery has been the main archaeological evidence able to survive thousands of years, while metal had a much shorter history, Chinese jade constitutes a unique line of additional information without equivalents in other parts of the world. No other cultures used jade continually from prehistoric times to modern. The images reflected in jade, whether real animals and other objects the ancient people encountered in their life, or imaginary figures they thought of in some obscure cultural process which we can only guess at, provide pointers to aid our groping understanding of the long gone civilizations. 
Some modern devotee-collectors of ancient jade attach mythical significances to their possessions, somewhat like Falungong followers about their qigong practices: that jade has a life, connects us with past spirituality, has a therapeutic effect, wards off harm, etc. While the smooth and cool touch of one's favorite piece of jade might well be psychologically comforting hence physically beneficial, (as is quiet meditation and regulated breathing of qigong), any further claims are largely a matter of imagination. There were Han emperors who consumed jade powder, together with dew collected from their gardens, believing that the heavenly fluids and ancient art concotion would bring eternal life, but they are not around to confirm that it worked.
The idea of "tray playing" a piece of jade also deserves a mention: if a newly excavated jade piece is regularly rubbed, either with fingers directly or wrapped in some smooth material like silk cloth, one gradually removes surface impurities originally stuck there, while adding some new material such as body oil; through a combination of better light penetration under a smoother surface, thus bringing out the inner colours, with surface colour shifts, the jade might take on a very different tinge. This is what led some to attribute life to jade.
