If a ruler perfectly observes the rites of the state, white jade will appear in the valley.
— Li Ji (Book of Rites, compiled approx. 300 BCE)
The Chinese have been continuously creative in working jade for more than six thousand years – from the Neolithic Hermadu culture (about 5000 BC) to the present. But China is hardly the only culture to place a high value on jade.
Jade of one type or another is found in Burma, Central America, Brazil, Canada, Japan, India, Siberia, Finland, Tanzania, and elsewhere; in this country, it occurs in California as well as in the northeastern and southwestern states. It is prized for its hardness, glassy luster, and rich translucent colors. Colors vary from white to green, but there are also red, yellow and lavender jades. In China, a clear emerald-green stone is valued most highly. According to ancient legend, yu, as the jewel is known, came from the holy mountains and was thought to be crystallized moonlight. In fact, jade came from along the Silk Road.
Because jade is extremely hard, it might have been tried early on for tools and weapons. But jade is also brittle, and the forms that have survived appear to have been used for symbolic, rather than utilitarian purposes. Jade clubs, for example, were used to represent authority among the Maori. Knives, daggers, and scepters were used in ritual or military ceremonies in China. Jade often possessed not just symbolic but belief-system significance – as seems the case with the mysterious bi discs and cong tubes found in Neolithic Chinese grave sites (the former is a disc with a hole in the center, the latter a tube that, in section, is square on the outside and round on the inside). Centuries later, the corpses of high-ranking officials were clothed in suits made of more than 2,000 thin slivers of jade sewn together with gold wire.
In ancient times, as today, jade was also used for personal adornment. Jade rings, bracelets, pendants, beads, and the like appear very early. Even today, the ring disk – a symbol of heaven – is still worn as a talisman; jade bracelets are believed to protect against rheumatism in some regions of China. Exceptional artistic effects can be achieved with jade – outside of Asia, some of the most stunning work was created by Central American artists of Olmec, Toltec, and Mayan cultures. Still, no culture can rival China for the breadth, depth, richness, and variety of work in this medium.
“Jade” is really several stones – or at least that is the usage of the Chinese word, yu, which was applied even to stones such as serpentine and aventurine that are no longer considered types of jade. The English word jade is properly applied to two distinct stones: nephrite and jadeite. Nephrite, either from local sources or imported from central Asia, was almost the only jade used by the Chinese until around the time of the American revolution when jadeite was introduced from Burma.
Although quite different in mineralogical composition, the two stones share many qualities. A milky, soft-colored stone, nephrite is a calcium and magnesium silicate with a tightly bonded, fibrous structure. It is usually white green or violet but can be other colors as well. Jadeite, a sodium and aluminum silicate, comes in more colors, ranging in tone from white to gray and in hue from yellow-orange to violet. But it is best known for the bright green of the highly polished form that is favored for jewelry, where it is cherished for its high luster. Jade’s spectrum of colors is the result of trace elements – such as magnesium in green jade or iron in jades with a yellowish hue – mixed in with the snowy white of the pure mineral.
— by the Education Department of the Asian Art Museum