Difference Between Jade and
Jadeite?
One significant difference
between jade and jadeite is where it comes from. Jade is actually from China
and is a material known as nephrite.
Jadeite mostly hails from Burma and at its highest is known as Imperial jade. It is more expensive
than what we call jade.
What is Jadeite?
Jadeite is a pyroxene mineral with
composition NaAlSi2O6.
It is monoclinic. It has a Mohs hardness of about 6.5 to 7.0 depending on the
composition. The mineral is dense, with a specific gravity of about 3.4.
Jadeite forms solid solutions with other pyroxene endmembers such as augite and
diopside (CaMg-rich endmembers), aegirine (NaFe endmember), and kosmochlor (NaCr
endmember). Pyroxenes rich in both the jadeite and augite endmembers are known
as omphacite.
Although jade is primarily
associated with the Chinese, who have venerated it for more than 5,000 years,
the gem owes its name to a group of far less well-known jade worshippers, the
Mayans of Central America. When the Spaniards conquered Central America in the
early 16th century, they found many Mayans wearing the stone to ward off or
cure kidney problems. This talismanic use inspired the Spaniards to call the
gem: piedra de l'e'jade,
"stone of the loins:' The
French shortened it, with characteristic panache, to le jade.
Today Occidentals laugh at the
superstition enshrined in the gem's name. But Orientals still take such beliefs
seriously. Yet even the East is bowing to modern jade custom. The jade they
wear for well-being is no longer the nephrite variety (a silicate of calcium
and magnesium) that the Chinese revered and on which jade's reputation is
largely based. Instead, they wear a Burmese
jadeite (a silicate of sodium and aluminum) to traditionalists an
interloper jade of no consequence in the gem's long illustrious history. This
jadeite was first imported into China late in the 18th century. Ironically, the
jade the Spaniards first saw in the New World 150 or so years before was a
cousin of Burmese jadeite found in Guatemala and possibly Costa Rica.
So, without knowing it, the
conquistadors predicted our own time's preference for jadeite over nephrite
when they coined the name the entire species is known by throughout the world.
But while its name is relatively new, basic attitudes about jade are ancient.
In fact, the gem may be the only one that is still used as much for an amulet
as for adornment. Experts estimate that millions of Orientals, Chinese
especially, wear jadeite jewelry for good luck and health. "Within every
Oriental there lurks a jade lover," says one Los Angeles jadeite
specialist. It's easy to see why.
Jadeite is formed in metamorphic rocks under high
pressure and relatively low temperature conditions. Albite (NaAlSi3O8) is a
common mineral of the Earth's crust, and it has a specific gravity of about
2.6, much less than that of jadeite. With increasing pressure, albite breaks
down to form the high-pressure assemblage of jadeite plus quartz. Minerals
associated with jadeite include: glaucophane, lawsonite, muscovite, aragonite,
serpentine and quartz.
Rocks that consist almost entirely of jadeite are called jadeitite. In all well-documented
occurrences, jadeitite appears to have formed from subduction zone fluids in
association with serpentinite. Jadeitite is resistant to weathering, and
boulders of jadeitite released from the serpentine-rich environments in which
they formed are found in a variety of environments.
Jadeite's color commonly ranges from white through pale
apple green to deep jade green but can also be blue-green (like the
recently rediscovered "Olmec Blue" jade), pink, lavender and a
multitude of other rare colors. Chloromelanite is a very dark green to
black variety. Color is largely affected
by the presence of trace elements such as chromium and iron. Its
translucence can be anywhere from entirely solid through opaque to almost
clear. Variations in color and translucence are often found even within a
single specimen. Jadeite is reported from California, USA; Myanmar (Burma); New
Zealand; Guatemala; other localities of jadeite include Kazakhstan; Russia;
British Columbia, Canada; Alaska, USA; Italy and Turkestan.
Over 100 axe heads made from jadeitite quarried in
northern Italy in the Neolithic era have been found across the British Isles.
Because of the difficulty of working this material, all the axe heads of this
type found are thought to have been non-utilitarian and to have represented
some form of currency or be the products of gift exchange.
Jadeite is a Cultural
Mainstay
For centuries, Chinese poets
linked jade's attributes-the most famous: steel-like
toughness-to those of the gods, while philosophers praised its virtues. So
esteemed was China's native jade, the nephrite variety, that its emperors,
accorded divine rights, spoke their prayers through ceremonial jade discs.
So why did Burmese jadeite
quickly rob Chinese nephrite of regard? Because the most prized nephrite-a
white, diaphanous variety called "mutton
fat jade" -became too scarce, leaving carvers to work with the more
common waxy green kind found today.
The green of this nephrite was no
match for the lighter green of the jadeite first imported into China from
neighboring Burma in 1784, after the two countries signed a trade pact. It was
called te tsui, which means "kingfisher feather,"
because its intense spectral green conjured up the color intensity of that
bird's feathers (which, in actuality, are blue). Such color, coupled with the
stone's luster and translucence, captivated Chinese carvers and artisans. Ever
since, jadeite has been the jade of preference worldwide. Indeed, nephrite is
valued mainly for its antiquity while jadeite is valued in and of itself.
A case in point: In 1965, a New
York gem dealer bought an antique jadeite Chinese archer's ring for $ 735.
After he had it cut into four cabochons, he got $10,000 for the stones.
That anecdote gives some idea of
the tremendous value placed on fine jadeite. As a result, Chinese dealers will
gamble tens, even hundreds, of thousands of dollars on jadeite rough (called
"boulders")-weighing anywhere from a few kilos to hundreds of
pounds-that they think will yield superb stones. The Chinese, for whom
high·stakes gambling is second nature, will occasionally buy a rough based only
on its outward appearance. "Surface flecks or stripes of green may
embolden them to bid on a boulder," says one New York jadeite importer.
More often, he continues, the
Chinese will buy based on evaluation of the rough after a small window has been
polished on its surface. ''That gives more of an indication of the quality one
can expect," he says, "but the risks are still enormous."
Although Burma is the sole source
of fine jadeite and Thailand its prime entry point (via smugglers) into the jewelry
world, Hong Kong is the gem world capital for
jadeite-indeed, all jade-today. According to one jadeite specialist, Hong Kong
dealers have very definite priorities when cutting jade rough. If a piece is
free of streaks and fractures, and deep enough, it is earmarked for cutting
into cabochons easily the most desirable form of jadeite. Next come, in
descending order, bangles, beads, carvings and discs (also known as
"doughnuts"). Jadeite is most often cut into carvings, including,
quite often, Buddhas, animals and crosses. Since jadeite is still used as a
talisman, these carvings prove extremely popular, especially in pendant form.
Gemstone Quality
in Jadeite
Jadeite comes in many colors
(including lavender and red), but green is the color that is most coveted.
Experts describe the ideal for this color in varying ways. One likens the
finest green in jadeite to that of liquid Prell concentrate shampoo. Another
compares the color to "the intense green shoots of a freshly seeded
lawn." Both are talking about what is called "imperial green," a
color very often likened to that of the finest emerald. Stones that exhibit
forest or spinach green are considered too dark; stones paler than a pleasing
apple-green are too light. But quality in jadeite isn't merely a matter of hue
and tone. It is a function of several factors:
1) COLOR
UNIFORMITY: Gemstones
should be free of blotchiness that imparts an unevenness to the color.
2) TRANSLUCENCY: Stones should be semi-transparent in
natural light.
3) CLARITY: Stones should be as inclusion-free as
possible when illuminated from beneath by a fiber-optics or pen-light source.
4) BRIGHTNESS: Stones should exhibit a lustrous brilliance
that some dealers describe as a glow.
When all these factors-hue, color
uniformity, translucency, clarity and brightness-are present to a high degree,
prices for 5-carat jadeite cabs will reach tens of thousands of dollars in the
few fine jewelry stores that carry them. Larger
top-caliber stones between 10 and 20 carats could cost $100,000, or even more.
But don't despair. Decent
jadeites around 3 to 5 carats are available for a fraction of such prices. Of
course, expect such stones to be nearly opaque to nearly translucent, veer to
either light or dark tones, be somewhat included and lack the high polish of
better jadeite. For a couple thousand dollars, however, consumers should be
able to find nice apple-green stones with good translucency, clarity and
brightness. One warning when buying jadeite: A lot of it is dyed. So make sure your jeweler guarantees in writing that your jadeite has
not been so enhanced or gemstones
treatment.
How to Tell Jade From Jadeite
What is a Jade?
Jadeite is one of the minerals recognized as the gemstone jade. The
other is nephrite. Jadeite from the Motagua Valley, Guatemala, was used by the
Olmec and Maya peoples, as well as the indigenous peoples of Costa Rica.
Typically, the most highly valued colors of jadeite are the most intensely
green, translucent varieties, though traditionally white has been considered
the most valuable of the jades by the Chinese, known for their carefully
crafted jade pieces. Other colors, like "Olmec blue" jade, which is
characterized by its deep blue-green, translucent hue with white flecking, are
also becoming more highly valued because of its unique beauty and historical
use by the Mesoamerican Olmec and also in Costa Rica; however, this variety was
only recently rediscovered and is only being minimally exploited by native
Guatemalans. It is thus difficult to obtain and as yet too rare and little
known to have attained great value as a gemstone. When purchasing jade, quality
is determined by the degree of translucence, cleanness of color and purity of
color. Occasionally, other minerals such as serpentine or quartz are sold as
jade but the difference can be determined by cleavage and hardness.
STEPS:
1) Become
familiar with real jade. Only
jadeite jade and nephrite jade are considered authentic jade.
a) The most expensive and desirable jadeite (Burmese Jadeite, Burma
Jade, Imperial Jade, or Chinese Jade) usually comes from Myanmar (formerly
Burma), but small quantities are mined in Guatemala, Mexico and Russia.
b) Seventy-five (75%) of the world’s jade come from the mines of British
Columbia in the form of nephrite, but that's also mined in Taiwan, the United
States and (in small amounts) Australia.
2) Test
the hardness using specialized equipment. The hardness of various minerals
is often measured on the Mohs scale,
devised by the German mineralogist Friedrich Mohs in 1812. On this scale,
nephrite usually registers at between 6 and 6.5. In comparison, jadeite tends
to be slightly denser and harder, measuring up to 7 on the scale.
a) Jadeite is very hard; it will scratch glass or even metal. Nephrite,
however, can be much softer, so performing a scratch test improperly may damage
a genuine piece.
b) Use the blunt end of a pair of scissors and gently press down and
draw a line on an area on the jade piece that is not visible (bottom or end of
the piece).
c) Avoid any weathering surfaces because these are much softer and can
be easily damaged. If the scratch makes a white line, gently wipe it off (it
might be metal residue from the scissors). Is there still a scratch? If so,
it's probably not authentic jade.
d) If it scratches glass or steel, it could still be many of the
alternatives to jade as well, including the various forms of green quartz and
prehnite.
e) Perform this test at your own risk. The piece may be very valuable,
even if it's not made from jade, and can lose significant value if scratched.
3)
Examine the fibrous structure. Experts with the right equipment are able
to tell nephrite jade from jadeite jade by looking at the specific fibrous
structures of the minerals. Nephrite has a looser interwoven filtrons structure
and, when fractured, can splinter or grain. When looked at under a powerful
microscope, however, jadeite has a much tighter interlocking granular
structure, which explains its extra toughness.
4) Study
the differences in chemical composition. Nephrite is classified as a
silicate of calcium and magnesium and is placed in the pyroxene group of
minerals. Meanwhile, jadeite is a silicate of sodium and aluminum and is placed
in the amphibole group of minerals due to its composition.
5)
Look at the color and markings. It can be very hard to tell the difference
between the two types of jade by going on color alone. Nephrite, for example,
is usually dark green or gray. However, it can also be white, black or even
translucent. Similarly, the color of jadeite varies markedly due mainly to the
presence of trace elements such as iron or chromium. The gem can be deep jade
green, but can also be white, translucent and even black.
6) Become
familiar with imitation jade. Materials passed off as jade include:
a) In New Zealand Greenstone or Pounamu is highly regarded by
Māori. Māori people recognize four main types of pounamu, identifying their
color and translucence: kawakawa, kahurangi, īnanga. These are all
nephrite. They also regard a fourth type of pounamu - tangiwai- from
Milford Sound which, although prized, is actually bowenite and authentic jade
in the eyes of the rest of the world.
b) Serpentine ("New Jade" or "Olive Jade")
c) Prehnite
d) Aventurine quartz
e) Grossular garnet ("Transvaal jade")
f) Chrysoprase ("Australian jade" - most of it comes from
Queensland, Australia)
g) Malaysia Jade (permanently dyed translucent quartz that may be called
by its color – Red Jade, Yellow Jade, Blue Jade)
h) Opaque dolomite marble ("Mountain Jade" - from Asia, dyed
in vibrant colors)
REFERENCES:
(Gia) Gemological. Gem
Reference Guide. City: Gemological Institute of America (GIA), 1988. ISBN
0-87311-019-6
Sorena Sorensen, George E.
Harlow, and Douglas Rumble, The
origin of jadeitite-forming subduction-zone fluids: CL-guided SIMS
oxygen-isotope and trace-element evidence. American
Mineralogist, v. 91.
Easby, Elizabeth Kennedy. Pre-Columbian Jade from Costa Rica.
(1968). André Emmerich Inc., New York
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