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Black Opal
"Of all precious stones, it is Opal that
presents the greatest difficulties of
description, it displaying at once the piercing
fire of Ruby, the purple brilliancy of Amethyst,
and the sea-green of Emerald, the whole blended
together and refulgent with a brightness that is
quite incredible".
Pliny the Elder (23-79 AD), Historia
Naturalis
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An Opal mine
in 1886, located at White Cliffs in
the Australian State of New South
Wales. Only discovered in Australia
in 1849, today around 95 percent of
the world's Opal hails from this
sunburnt country |
In my mind, Pliny the Elder was the leading
authority on gemstones in the classical world,
and the reason he's quoted a lot in this book,
is that 2,000 years on, many of his observations
still ring true. Back in Pliny's day, Opal
pretty much came from one place in the world, Czernowitza in modern-day Slovakia (formerly
part of Hungary, thus the old term 'Hungarian
Opals'). Rome never did manage to make it part
of their Empire, so it retained an exotic appeal
and genuine rarity, which along with its unique
physical beauty, assured its popularity. But
before Rome there was Greece, and while
Herodotus, Plato and Theophrastus gave Opal a
plug, around 500 BC, Onomacritus, compiler and
forger of oracles (yep, he got busted) said,
"The delicate colors and tenderness of the Opal
remind one of a loving and beautiful child".
This comparison probably isn't originally his;
ancient Greeks and Romans often compared Opal's
beauty to that of a favourite child. While both
cultures cherished Opals, the Greeks believed it
possessed the power of foresight, invisibility
and prophecy, while the Romans considered them
symbols of hope, love and purity. The Romans
even wore them as talismans for protection from
danger, which is definitely apt for a gemstone
with a rainbow trapped within.
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Black Opal &
Diamond 9K Yellow
Gold Ring |
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Moving ahead in history, Shakespeare used Opal a
lot in his plays to portray lavish magnificence,
calling it, "this miracle queen of gems" in
'Twelfth Night'. Queen Victoria, much like
Cleopatra's second Roman boyfriend Marc Anthony,
was a ruler big on Opal. In fact, she actively
dispelled myths of Opal being unlucky as a
result of people missing Sir Walter Scott's use
of metaphor in 'Anne of Geierstein' (1829).
If Pliny liked European Opal, he would have gone
wild for the Australian Black, the 'king of
opals'. While I try not to play favourites,
Black Opal is definitely special to me. After
all, since 27th July 1993, Opal has been
Australia's national gemstone. This is not
surprising, considering 95 percent of Opal hails
from my homeland, but I guess we should also
remember that Australia's Opal fields are bigger
than those found in the rest of the world
combined. With only 25 percent of Opal mined gem
quality, understanding this October birthstone
is easier than you think.
Our modern word for this gem has an interesting
entomology. Opal is derived from the Roman 'opalus',
which in turn is from the Greek 'opallios',
meaning 'to see a change'. While another
possible Greek origin is 'opthalmios'
(eyestone), the original source of the name is
probably the Sanskrit 'upala' (precious stone),
lending credence to India once being a source of
Opal for ancient Rome.
To understand how Australian Opals were formed,
we have to travel back in time 140 million
years. Dreamtime legends passed down by
storytellers have been part of indigenous
Australian culture for over 60,000 years. For
tribes from the Andamooka region in South
Australia, the Opal was known as the 'fire of
the desert' and was linked to creation myths.
Their ancestral creator came down to earth on a
great rainbow, which turned the rocks it touched
into resplendent Opals, coloured with the hues
of a rainbow.
In reality, we need to look to a huge inland sea
and a resulting geological feature called the
'Great Australian Basin'. The majority of
Australia's Opal fields are located in the basin
and were formed from the weathering of sandstone
deposited over older host rock. The structure of
Opals is unique and comprised of tiny spheres of
silicon dioxide forming a pyramid-shaped grid,
interspersed with water. It's the refraction of
light through the spaces between these spheres
that produces Opal's characteristic and unique
'play of colour' - the flashes of colour that
change with the angle of observation. Interestingly, Opal without 'play of colour' has its silicon dioxide spheres more randomly arranged. Apart from
their colourful brilliance, Australian Opals are
also valued for their stability, a key
consideration for a gem containing around six
percent water.
Now famous across the world for its brilliant
colours, Australian Opal was discovered in 1849
and by the end of the nineteenth century started
to dominate the world's supply. But this wasn't
without some initial resistance. Perhaps a
little recalcitrant, the Hungarians claimed Aussie Opal
wasn't the 'real deal', despite the fact that by
the twentieth century, their own deposits were
pretty much exhausted. Today, most Opal is
sourced from a handful of Australian mining
areas, including Andamooka (1930), Coober Pedy
(1915), Lightning Ridge (1902), Mintabie (1931),
White Cliffs (1890) and the Queensland Boulder
Opal fields (a vast area discovered in 1869
centring around the town of Quilpie).
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Jelly Opal,
also known as Crystal Opal, is
transparent to translucent and
because of the absence of either doesn't have a body colour or
if present is described as White
Crystal Opal, Dark Crystal Opal or
Black Crystal Opal. While Jelly Opal
is found in all Australian gem
deposits to some degree, this
specimen hails from Andamooka in
South Australia
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Before we cover how to judge a Black Opal, it's
important to know how different Opals are
classified. While there are several
classification systems, they all relate to the
host rock (also known as 'potch' or 'matrix') on
which Opal forms and their resulting transparency and body colour (the base colour on
which Opal's 'play of colour' is visible). Black
Opal has a black body colour and may be opaque
with some translucency, particularly when held
to a strong light source. While the main
classifications are included under photographs
in this section, Grey Opal is a term seldom
used, with its specimens typically being grouped
in the 'black', 'dark' or 'semi-black'
categories, but it is translucent to opaque with
a grey body colour. Opaque Opal with ironstone
(boulder) potch included in the cut is called
Boulder Opal. Take note that not all Opal has
'play of colour'. Fire Opal is transparent to
translucent crystal Opal with virtually no 'play
of colour', displaying oranges, reds, yellows
and, since a recently discovered Brazilian
deposit, also blues. Peruvian Opal is a rare
variety that exhibits exquisite translucent
blues, pinks and greens, also without 'play of
colour'. Another variety with no 'play of colour'
is the translucent yellow and green Opal from
Tanzania.
As each Opal displaying 'play of colour' has its
own personality, individual preferences play a
big part. Despite this, Black Opal is the most
valuable variety, simply because of the contrast
and intensity afforded by its black body colour.
One way to understand this is to imagine
painting a row of windows black (Black Opal),
grey (Semi Black Opal), white (White Opal) and
colourless (Jelly Opal), then randomly spray
painting each window in all the individual
colours of the spectrum: blue, green, orange,
red, violet, and yellow. Obviously, the window painted black is going to make the colours
appear more intense. This is key to appreciating
Opal, because when 'play of colour' is present,
its value lies in the brilliance, brightness and
strength of colours displayed.
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Matrix Opal,
also called 'opal with matrix', is
any Opal where the host rock is
visible face up. This specimen is
from Central Queensland and shows a
black host rock (matrix) embedded
with brilliantly colourful flashes
of Opal |
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Superficially, assessing Opals appears
incredibly simple, but when an expert starts
dissecting the combinations of colours and
patterns possible, much like Jade, you're
heading into complex territory. But thankfully,
there are some easy to understand paradigms that
not only apply to Black Opal, but any Opal
displaying 'play of colour'. Just be aware that
for darker coloured Opal (black and semi-black)
opacity demands a premium and in lighter Opals
(white and jelly) transparency demands a
premium. In the marketplace, there is a definite
hierarchy of colours, with red being the most
valuable, followed by orange, yellow, violet,
green, and then blue.
Opals whose 'play of colour' flashes in the rare
reds are generally more valuable than those with
just blue and green, but as with all gemstones,
colour preferences are subjective.
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Semi Black
Opal (also known as Dark Opal) is
translucent to semi-translucent and
has a body colour in-between grey
and black. As Black Opal is
generally more opaque, opacity is
the criterion that divides black and
semi-black Opal. This example is
from n South Australia |
An Opal with a 'play of sing
more than half of one colour is named for its
primary hue, while an Opal with three or more
hues is called 'multicolour'. Even though the
presence of red increases a Black Opal's rarity
and value, it's typically valued lower than a
multicolour that shows several colours. The
patterns of colour also affect value, with large
patches of colour priced higher than those with
small patches of colour. Professionals often
communicate these patterns using colourful
self-explanatory names such as Chinese writing,
harlequin, peacock and pin-fire. While 'play of
colour' and strong opalescence (the silver to
bluish-white light that shimmers and glides over
an Opal's surface) rarely exist together, Opal
with an opalescence that reduces the brilliance
and intensity of its colour play will be priced
accordingly. The biggest thing to remember is
that due to its layered colours, Opal is
probably the most 'artistic' of all gemstones.
So when making your selection, try remembering
the old saying, "I don't know much about art,
but I know what I like".
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White Opal,
also known as Light Opal, is the
darling of everyday fashion
jewellery. It is translucent to
opaque with a white body colour.
Coober Pedy in South Australia is
the main source for this variety.
Named for its Opal miners, 'Coober
Pedy' means 'white man's hole in the
ground' and is a corruption of a
local indigenous Australian phrase,
'kupa-piti' (boys' waterhole) |
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Once you've settled on a colour
play you find appealing, you must consider the
cut. Thankfully, assessing cabochons is
straightforward, just look at their finish,
shape and proportion. While symmetrical ovals
will demand a premium, Opal that is cut too thin
or thick, whose dome is too shallow, or has a
finish that is cracked or crazed, will be priced
accordingly. Due to their rarity, slithers of
Black Opal are sometimes joined with other
material to create doublets (Opal plus a backing
material) or triplets (Opal with a top as well
as a back). These are understandably more
affordable, but do be aware that these are
manmade composites that should be sold as such.
Although Opal is relatively durable, it does
have some special care requirements (click here for more). While Black Opal is primarily
sourced from deposits at Lightning Ridge in New
South Wales, production at Lightning Ridge is
half of what it was 10 years ago. Unfortunately,
this is somewhat echoed at all of Australia's
major Opal deposits, markedly increasing
scarcity. Apart from Australia, other Opal
sources include Brazil, Ethiopia, Mexico, Peru,
Tanzania and the U.S.A.
As colourful as its country of origin, Black
Opal is definitely a gemstone with its own
unique personality and character. Like Australia
itself, Black Opal is easy to appreciate; it's
easy to become enchanted by its unrivalled
beauty. In the words of the famous Australian
poet Dorothea MacKellar: "An Opal hearted
country a wilful lavish land, all those who have
not loved her you will not understand".
Blue Fire Opal
Newness, rarity and beauty are what make Blue
Fire Opal special. The debut of Blue Fire Opal
has been shifting perceptions in play since the
time of the Aztecs; namely, Fire Opal is red,
orange or yellow. Blue Fire Opal is transparent
to semi-translucent, with a colour similarity to
pastel Tanzanite, pretty icy cool violet-blues
to steel blues. It also has occasional
opalescence, the milky blue appearance of Opal
caused by the reflection of light, which combos
nicely with its body colour. The first
significant production of Blue Fire Opal
occurred in December 2007, when it was
discovered by sheer chance at the Boca Rica Mine
in Brazil's Piaui State (pronounced: Pee-Ow-Ee).
The Piaui State has garnered praise aplenty for
its Opals, being compared to those from
Australia. With less than one-tenth of a percent
of the rough mined useable, the monthly output
of Blue Fire Opal is sporadic.
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Fire Opal
Fire Opal, also known as Mexican Opal,
Mexican Fire Opal, Cherry Fire Opal or Sun Opal,
is aptly named for its transparent to
semi-translucent fiery reds, oranges and
yellows. Treasured in the Americas since the
time of the Aztecs, Fire Opals were once called
'quetzalitzlipyollitli' and while I can't
pronounce this word, it means 'gemstone of the
bird of paradise'. Fire Opal is mainly found in
Mexico, but it has also been unearthed in
Brazil, Ethiopia, Mali, Tanzania, and
occasionally Australia.
| Thanks to Australian movies,
television and tourism advertising,
you're probably already aware of some
classic Australian slang like 'G'Day
Mate', but unless you've visited an Opal
field, terms like 'floaters', 'noodling'
and 'ratters' will probably fall on deaf
ears. Well, I'm here to help! Floaters
are Opal that is visible from the
surface and typically indicative of an
underground deposit, noodling is hunting
through old mine tailings to find Opal
that others missed and ratters are
people who poach Opal from another's
claim - a big no, no that was once
arbitrarily and severely punished! |
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