Origins and General Information of Natural Zircon Gemstone

According Indian Hindu mythology, Zircon was one of the many gemstones of fthe ?Kalpa Tree?. The mythological tree was a symbolic offering to the gods, and was described by Hindu poets of the 19th century as a glowing ensemble of precious stones like sapphires, diamonds and topaz. Green zircon was said to represent the lush green foliage of the tree.

In some parts of the world zircon was believed to protect the wearer from traveler?s diseases, injuries and to ensure a good sleep and a warm welcome to new places.

Composition of Zircon Gemstone

Zircon is a zirconium silicate (Zr SiO4). Its fspecific gravity is 3.90 to 4.10 and 4.67 to 4.70 and its refractive index range is between 1.79 - 1.81 and 1.925 -1.984. Its hardness on Mohs scale is 7-7.5. Zircon jewelry should be stored and handled carefully because although it is relatively hard gemstone, zircon can suffer from abrasion and the facets can be chipped with the slightest knock. Gem dealers often wrap zircons in individual pieces of paper so that the stones do not knock against each other.
 
Zircon crystal is one of the heaviest gemstones, which means that a zircon gem will look smaller in physical size than other gemstones of the same weight.

Varieties of Zircons

Zircon has a two varieties, one is called High Zircon and the other Low Zircon. Gemologists mainly use this nomenclature to differentiate between the two types of zircon which vary only in their properties.

Physical Properties

Zircon Colour

Natural zircon crystal originally comes in earthy brown, yellow, strong green and bright red. Heated or treated zircons can come in variety of colors from colorless white, yellow, red, blue. Purple, bright red etc.

Cut

Zircon gem stones are cut and faceted into many fancy shapes like oval, round, square etc.

Carat

1 carat to 5 carat zircon gemstones are mostly used in jewelry , but big sizes up to 25 carats are also not uncommon.

Clarity

Zircon of good fine quality are always transparent. Any visible flaw or inclusions in the gemstone diminishes the value of this gemstone substantially.

Price, Cost and Buying of Zircon Gemstone

Since there is no much demand in the market nowadays zircon gemstone has just become a collector gem and price of clean, good quality eye clean zircon can range from a mere $1 per carat (for reasonable good ones) to $25 per carat (for extremely good ones ).

color and clarity are the most important considerations in evaluating Zircon gem. The most beautiful, prized and rare color is deep red, next is pure, intense  blue and sky blue. colorless, orange, brown and yellow are less valued. It should have a very good luster and the facets should not be abraded. The word zircon or blue zircon conjures up an image of a diamond in most minds, this is because, since the 19th century, colorless zircon or white zircon was the best known simulant to the diamond and was widely used as a low price diamond alternative.

Zircon Gemstone is one of the most brilliant gemstones, second only to the diamond in brilliance. A superior brilliance and good dispersion are the distinguishable qualities of zircon gemstone. he word zircon is believed to have been derived from two Arabic words Zar that means gold and Gun which means color. In the 6th Century A.D. zircon was used in Greece and Italy. However, in the 14th century A.D. faceted zircons where sold as diamonds. The colorless white zircons of Sri Lanka where sold under the name of ?Matura Diamond?. Zircon gemstone is also called as the April birthstone.

Markets and Producers of Zircon

The Chanthaburi region in Thailand, the Palin region in Cambodia, and the southern part of Vietnam near the Cambodian border are the major sources where Zircon roughs are mined and sold. Other places where gem quality zircon mines are located are Srilanka (Ceylon), Myanmar, Australia, New England, France etc

Treatments on Zircons

Heat treatment in genuine zircon roughs results in colorless and blue colored zircon.

In the 1920s, a blue zircon gem stone made an entry into the gemstone market. Endowed with spectacular brilliance, this zircon was an immediate success. Later on, investigations and close inspections revealed that a large deposit of unattractive brown zircon had stimulated color improvement experimentation by the local entrepreneurs. Heating in an oxygen free environment had turned this brown mineral into attractive and beautiful bright blue gem. When the treatment process was revealed, the gemstone market simply accepted the information and the demand for this new blue zircon gems continued unabated.

One must keep in mind that natural untreated zircon crystals are very rare and most of the zircons available in the market today are heat-treated and that the color of some of these heated stones may change over time. 

Simulants of Zircon

Gems like tourmaline, garnet, quartz, synthetic Spinel, sphene and diamond are some of the gemstones which resemble zircon.

Interesting Trivia and other Facts

Like the peridot gemstone, zircon should also be used in jewelry where wear and tear is minimal like pendants, brooches etc. Due of its doubly refractive property genuine zircon gemstone can be easily distinguished from a diamond and synthetic cubic zirconia, which are singly refractive.  

Reference

1) Webster
2) Gemmology by Peter G.Read
3) Handbook of Gem Identification -   Richard  T.Liddicoat, jr
4) Gems and Crystals - From the American  Museum of Natural History - Anna S.Sofianides  and George E.Harlow.