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Nephrite can be found in a creamy white form as well as a green
color, while jadeite shows more color variation. Of the two, jadeite
is rarer, and is the form of jade mostly used in Central America.
Nephrite jade was used mostly in China, Myanmar and New Zealand.
Jade is the official gemstone of British Columbia, where it is found
in large deposits in the Lillooet and Cassiar regions. During
Neolithic times, the key known sources of nephrite jade in China for
utilitarian and ceremonial jade items were the now depleted deposits
in the Ningshao area in the Yangtze River Delta (Liangzhu jade
culture 3400–2250 BC) and in an area of the Liaoning province in
Inner Mongolia (Hongshan culture 4700–2200 BC). Jade was used to
create many utilitarian and ceremonial objects, ranging from indoor
decorative items to jade burial suits. From about the earliest
Chinese dynasties until present, the jade deposits in most use were
from the region of Khotan in the Western Chinese province of
Xinjiang. There, white and greenish nephrite jade is found in small
quarries and as pebbles and boulders in the rivers flowing from the
Kuen-Lun mountain range northward into the Takla-Makan desert area.
River jade collection was concentrated in the Yarkand, the White
Jade (Yurungkash) and Black Jade (Karakash) Rivers. From the Kingdom
of Khotan, on the southern leg of the Silk Road, yearly tribute
payments consisting of the most precious white jade were made to the
Chinese Imperial court and there transformed into objets d'art by
skilled artisans as jade was considered more valuable than gold or
silver.
Jadeite with its bright emerald-green, pink, lavender and brown
colors was imported from Burma to China only after the 17th century
and became known as Feitsu or Kingfisher (feathers) Jade.
In New Zealand, where it is known as greenstone or pounamu, nephrite
was fashioned for centuries by Maori to make weapons and ornaments,
and is still widely used to make carved jewellery although the
mining of it is restricted and closely monitored.
Besides the terms already mentioned, jadeite and nephrite are
sometimes referred to by the following:
Jadeite
Agate verdâtre, Feitsui, Jadeit, Jadeita, Natronjadeit, Yunnan Jade,
Yu-stone, Sinkiang jade
Nephrite
Aotea, Axe-stone, B.C. Jade, Beilstein, Grave Jade, Kidney Stone,
Lapis Nephriticus, Nephrit, Nephrita, Nephrite (of Werner), New
Zealand Greenstone, New Zealand Jade, Spinach Jade, Talcum
Nephriticus, Tomb Jade
In Asian culture, wearing jade is considered to bring good luck.
Many minerals are sold as jade in China. Some of these are:
serpentine (also bowenite), carnelian, aventurine quartz, glass,
grossularite, Vesuvianite, soapstone (and other steatites such as
shoushan stone) and recently, Australian chrysoprase. "Korean jade,"
"Suzhou jade," "Styrian jade," "Canadian jade," "Olive jade" and
"New jade" are all really serpentine; "Transvaal jade" is
grossularite. Other names for jade in China are: "Honan jade," "Metajade"
and "Xinjiang jade."
Jade may be enhanced (sometimes call "stabilized"). There are three
main methods, sometimes referred to as the ABC Treatment System:
Type A jadeite has not been treated in any way except surface
waxing.
Type B treatment involves exposing a promising but stained piece of
jadeite to chemical bleaches and/or acids and impregnating it with a
clear polymer resin. This results in a significant improvement of
transparency and color of the material. Currently, infrared
spectroscopy is the only test for the detection of polymer in
jadeite.
Type C jade has been artificially stained or dyed. The red color of
Red jade can be enhanced with heat. The effects are somewhat
uncontrollable and may result in a dull brown. In any case,
translucency is usually lost.
Type A treatment is the only acceptable enhancement by professional
collectors.
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