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Locations: |
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| Colors
Found: |
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Blue, brown, cream,
green, grey, lavender, red, white & yellow |
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| Family: |
Jade |
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Hardness: |
6.50 |
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Refractive Index: |
1.61 - 1.63 |
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Relative Density: |
2.90 - 3.10 |
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For centuries, Nephrite Jade and the other
Jade variety Jadeite were considered one and the same. It was not until
1863 in France that they were identified as different minerals with a
similar appearance and properties.
The name Jade was first used around the time of the Spanish conquest of
Central and South America and is from the Spanish “piedra de ijada”,
meaning hip stone, as it was thought to cure kidney stones and other
kidney ailments.
While Jade was known as the “stone of heaven” in ancient China, the
Chinese word for Jade, Yu is not generally used. Jade was excavated from
the Kunlun Mountains of northwest China, from 5000 BC, and even today
China remains an important source for this gemstone.

In Russia, it has been mined and crafted
since 3000 BC. Tsar Alexander III’s sarcophagus was carved from Jade.
For about 3,000 years Jade has been highly prized by the Native North
Americans of British Columbia, Canada who called it “Greenstone” and for
centuries the New Zealand Maori have made beautiful Nephrite carvings.

Nephrite is composed of silica and magnesia and its color is
determined by the amount of iron present in the mineral. A lesser iron
content produces lighter colors such as white, cream, yellow, grey,
green, blue, red, brown and lavender. A greater iron content produces
the darker colored Nephrite, such as darker grey and darker green.
Nephrite has the highest tensile strength (toughness as opposed to
hardness) of all natural gemstones and in fact has a tensile strength
greater than some steel. It is so strong that it cannot be chiseled. It
must be ground using sharp abrasives.
Interestingly, less than 0.05% of Nephrite extracted is of gem quality.
Nephrite is typically not treated as it is less likely to take up dye or
stains than Jadeite. Older pieces benefit from polishing to retain their
luster.
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