ZIRCON: Not the same Gem as Cubic Zirconia
Zircon has long had a supporting role to more well-known gemstones, being used as an accent stone for many years. The name probably comes from the Persian word zargun which means "gold-colored," although zircon comes in a wide range of different colors. Before the 1960s, Zircon was most often used to simulate diamond. As a result, the most popular shade was the colorless variety which looks more like diamond than any other natural stone due to its brilliance and dispersion. Use of Zircon as a simulant fell out of favor when the superior synthetic diamond simulants arrived such as YAG, GGG and cubic zirconia. The popularity of natural zircon today suffers because of the similarity of its name to cubic zirconia, the common and inexpensive laboratory-grown diamond imitation. However the two are completely different minerals and gems. This similarity of name occurs because both contain the rare metallic element zirconium. As a result of this bad press, some people think this fine gemstone is a merely cheap synthetic stone and don't realize that there is actually a beautiful natural gemstone called zircon.
Currently, the most popular color for this gem is the blue zircon. Most blue zircon,
which is considered an alternate birthstone for December, is normally a pastel
to medium blue in color, but some
exceptional gems have a bright blue color. Beyond blue, Zircon is also available in green,
deep red, yellow, brown, and orange. Color and clarity are the most important factors in
evaluating zircon. True red and deep blue are the rarest and most highly valued.
Zircon gems are usually quite clan, so any visible flaws
reduce the value considerably. The brilliance and beauty of this gemstone makes it very
popular and is reasonably priced in comparison with most other gems. The wide variety of
colors of zircon, its rarity, and its relatively low cost make it a popular collector's
stone. Collectors enjoy the search for all possible colors and variations.
The lighter colored specimens reveal the high optical dispersion (rainbow of
prismatic colors) which is found in this gem. It is also one
of the heaviest gemstones, which means that it will look smaller than other varieties of
the same carat weight. Zircon jewelry should be stored carefully because although zircon
is relatively hard, it can abrade and facets can chip. Dealers often wrap zircons in
individual twists of paper to protect them so that they will not knock against each other in a parcel.
ZIRCON FROM AROUND THE WORLD
Zircon is mined in Cambodia, Sri Lanka, Thailand, Myanmar, Australia,
and Tanzania in east Africa. Cambodia, Sri Lanka, Thailand, Myanmar produce brown and
occasionally blue or green material that comes from gravel deposits. Tanzania produces a
golden orange to yellow material that is available in large sizes. Another deposit in
Tanzania also produces a red colored material. An unusual occurrence of sage green (also
sometimes called "low" zircon) material occurs in the Tunduru gem gravels of
TREATMENTS FOR ZIRCON
Nearly all blue zircons are heat-treated from a brown material this ability to turn brown Zircon to blue was discovered less than a century ago. In the 1920's, large quantities of a new gemstone suddenly appeared on the market. George Kunz, the legendary Tiffany's gemologist suspected trickery. He dispatched a colleague to Siam (now Thailand) and learned that a very large deposit of brown zircon had recently been discovered. The local gem traders had learned to heat the brown zircons in an oxygen free environment to produce dazzling blue stones. To this day, the border area of Thailand and Cambodia remains the largest producer of gem quality zircons. Many brownish Zircons from other locations can also be heat treated. If heating is done in an oxygen rich environment (free access to air) the stones turn to a colorless form, if the blue color is desired, heating is done in an oxygen starved environment. The treatment is permanent and well accepted in the gem trade. The Tanzanian material cannot be heated to turn blue.
CHOOSING A ZIRCON
Like many colored stones, the value of zircon is largely dependent on
the color and clarity. The rarest and most valuable of of all the zircon are the deeper
blue and pure red stones. Green Gems of low Zircon are also very rare and unusual, but not
as valuable. Clean blue zircon gems over 10 carats are uncommon, and they are priced
accordingly. All Zircon gems should be clean and well cut.
Like many colored stones, the value of zircon is largely dependent on the color and clarity. The rarest and most valuable of of all the zircon are the deeper blue and pure red stones. Green Gems of low Zircon are also very rare and unusual, but not as valuable. Clean blue zircon gems over 10 carats are uncommon, and they are priced accordingly. All Zircon gems should be clean and well cut.
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