About Gems
October-Opal/Tourmaline
The Insight
In Twelfth Night, Shakespeare referred to Opal as "the queen of
gems'.
" The Roman historian Pliny described it as having "the fire
of the carbuncle, the brilliant purple of the amethyst and the sea green
color of the emerald, all shining together in incredible union ' "
The Romans considered opal a symbol of hope, an appropriate attribute
for a gem with a rainbow locked within it. The Arabs believed opals fell
from heaven in flashes of lightning, thus acquiring their fiery colors.
These romantic notions are inspired by one of the most uniquely
beautiful gemstones nature has ever produced-the dramatic, mysterious
opal. The phenomenon displayed by opal is called play of color. It is
caused by the diffraction of light set up by the layers of silica
spheres in its composition. The effect is similar to the rainbow colors
displayed on a soap bubble, only much more dramatic.
In the 19th century opal acquired a stigma through its role in the plot
of a novel by Sir Walter Scott, Anne of Geierstein. The heroine owned an
opal that burned fiery red when she was angry and turned ashen grey upon
her death. Queen Victoria finally dispelled the curse by giving opal
jewelry wedding presents to her relatives.
Opal has long been regarded as an October birthstone, sharing the
spotlight with Tourmaline. The famous French actress Sarah Bernhardt was
born in October and never considered herself well-dressed unless she was
wearing opals.
Varieties
The most treasured variety of opal is black opal with strong play of
color, that is, brilliant flashes of different colors. Black opal is so
called because of its dark background color.
The variety known as white opal has a light background, and the colors
displayed lean toward the pastel hues.
Crystal opal has a colorless background and exhibits play of color,
but, unlike white or black opal, it lets light pass through it.
Fire opal is also fairly transparent, but its background color may be
yellow, orange, red or brown. Sometimes it doesn't even have the typical
play of color. It's often called Mexican opal because Mexico is a major
source of this type. Fire opal with a red body color is also known as
cherry opal.
Opal that is colorless, transparent to semitransparent and has little
or no play of color is called jelly or water opal.
Opal quality is judged by the number of colors exhibited and the
evenness of the pattern.
Australia's Gift
Australia is the world's most important source of opal. The opal miner
is a strange breed of individual. He chooses to lead a Spartan life in a
particularly barren and dry corner of the world while he searches for
his rainbows. To escape the extreme temperatures, he must burrow a home
underground.
Opals are usually found in Sandstone or Claystone. Deposits are spread
over a wide area, and there is little clue to their location. Mining is
done on a small scale with hand-operated machinery and small tools. A
pocket knife might be the final instrument to loosen an opal from its
host rock.
Imitating Nature
Over the past century scientists have become highly skilled at creating
laboratory facsimiles of fine gemstones. Far from being mere
look-alikes, these synthetic gems are made of exactly the same material
that nature uses and mimic the natural structure perfectly.
Synthetic opal first came on the market in 1974 and has been improving
ever since. A skilled gemologist can distinguish it from natural opal by
viewing it under magnification, but to the untrained eye it looks
natural.
Versatile
Because opal displays a whole rainbow of colors, it can be worn with
any color outfit. It is usually cut in a dome shape and set in rings,
earrings, pendants, bracelets and pins. It may be joined by accents of
ruby, sapphire or emerald to enhance particular color flashes in the
gemstone. A fine opal piece is often guarded in a web of small diamonds
as are other exceptional colored gems. Some opals are fashioned into
beads for a major contribution to a woman's total look
Tourmaline's name comes from the Sinhalese word "turmali,"
which means "mixed." Bright rainbow collections of gemstone
varieties were called "turmali" parcels. Tourmaline, occurring
in more colors and combinations of colors than any other gemstone
variety, lives up to its name. There is a tourmaline that looks like
almost any other gemstone! Many stones in the Russian Crown jewels from
the 17th Century once thought to be rubies are actually tourmalines.
Perhaps this is why this gemstone is said to encourage artistic
intuition: it has many faces and expresses every mood.
The Empress Dowager Tz'u Hsi, the last Empress of China, loved pink
tourmaline and bought almost a ton of it from the new Himalaya Mine,
located a long way from the Middle Country in California. The Himalaya
Mine is still producing tourmaline today but the Dowager went to rest
eternally on a carved tourmaline pillow.
Tourmaline is also of interest to scientists because it changes its
electrical charge when heated. It becomes a polarized crystalline magnet
and can attract light objects. This property was noticed long ago before
science could explain it: in the Netherlands, tourmalines were called "aschentrekkers"
because they attracted ashes and could be used to clean pipes!
Tourmaline occurs in every color of the rainbow and combinations of two
or three colors. Bicolor and tricolor tourmalines, with bands of colors
are very popular. Sometimes the colors are at different ends of the
crystal and sometimes there is one color in the heart of the crystal and
another around the outside. One color combination, pink center with a
green rind, is called "watermelon tourmaline" (seedless, of
course!) Sometimes designers set slices of the crystal instead of
faceted stones to show off this phenomenon.
Almost every color of tourmaline can be found in Brazil, especially in
Minas Gerais and Bahia. Pink and green colors are particularly popular.
In 1989, miners discovered tourmaline unlike any that had ever been seen
before. The new type of tourmaline, which soon became known as Paraiba
tourmaline, came in incredibly vivid blues and greens. The demand and
excitement for this new material, which soon fetched more than $10,000
per carat, earned more respect for the other colors of tourmaline.
Pink and green tourmalines are now widely available and are especially
popular in designer jewelry. Blue tourmalines are also very much in
demand but the supply is more limited.
Tourmalines are most often cut in long rectangular shapes because of
their long and narrow crystal shape. Tourmaline crystals are beautiful,
pencil thin and ridged, and they are also sometimes set in jewelry. Some
designers also set rainbows of tourmaline in each color of the spectrum.
Tourmaline is strongly pleochroic: the darkest color is always seen
looking down the axis of the crystal.
In addition to Brazil, tourmaline is also mined in Tanzania, Kenya,
Madagascar, Mozambique, Namibia, Afghanistan, Pakistan, Sri Lanka, and
California and Maine in the United States. Maine produces beautiful
sherbet colors of tourmaline and spectacular minty greens. California is
known for perfect pinks, as well as beautiful bicolors.
One particularly beautiful variety is chrome tourmaline, a rare type of
tourmaline from Tanzania which occurs in a very rich green color caused
by chromium, the same element which causes the green in emerald.
Tourmaline is a hard and durable gemstone which can withstand years of
wear.
