possessing
certain magical properties. It is placed above all the other precious
stones in China, and is carved into elaborate figures and designs. The
Chinese believe that jade embodies the five cardinal virtues of
charity, modesty, courage, justice and wisdom and the wearer gets
immunity from accident and misfortune. Most of it went to
China, but a demand has grown up in western countries as its wonderful
colour and decorative value began to be appreciated. There is not much
demand for jade in India. The stone takes a very good polish, and the
polished surface has an oily lustre.
The
term jade includes two minerals of similar appearance: (1) nephrite,
and (2) jade. Nephrite is the more common form of jade. It is a
monoclinic amphibole, compact, tough and the fracture is splintery.
Hardness = 6 to 6-1/2. Specific gravity = 2-9 to 3-1. Colour: white to
leaf green and grass green due to ferrous iron. It is translucent to
opaque; pleochroic, mean refractive index = 1-62. Composition: Ca(MgFe)8(Si03)4.
Jadeite belongs to the pyroxene group and is rarer than nephrite,
tough, compact and splintery. Hardness = 6-1/2 to 7. Specific gravity =
3-3. Colour: White, greenish white or emerald green. Lustre:
Subvitreous to pearly. Mean refractive index = 1-66. Composition:
NaAl(Si03)2. It fuses more readily than nephrite. Jadeite has a granular structure, whereas nephrite is a matted aggregate of fibres.
. Uses
Jadeite
is used for making buttons, bars and brooches, small pieces for making
bracelets, and beads for necklaces and bangles. Jadeite is also very
much used for carvings in China.
Grades
1. Mya Yay or Yay kegauk.—This is the most precious variety, and is translucent with a uniform grass-green colour.
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