The Misrepresented Zircon
Zircon, chemically known as ZrSiO4, is the oldest mineral of the earth originating from all three different rock types: igneous, metamorphic and sedimentary. Zircons also have an immense variety of facts such as: being in the tetragonal crystal system, being doubly refractive and having a high birefringence. Despite these facts, the most important piece of history concerning the Zircon was its use as an imitation of diamond in the 1900s. Some people’s brilliant-cut diamonds in rings during those periods were, in fact, a colourless zircon, which has a profound sparkle similar to the diamond(caused by the high refractive index). It is unfortunate in the current day and age where the previous notoriety of the stone has overshadowed the beauty, colour range and value which the stone has. Therefore, aiming to build the reputation of Zircons in a new light, this publication presents the Zeal of Zircons.
Geographical Occurrence of Zircons
The discovery of zircons happens all over the world due to their presence in all types of rocks. However, just like any other gemstone, there are countries that gain popularity as leaders in zircon production. A country which The Gem Monarchy is proud to be based in Australia. Australia is the leading largest country in Zircon mining, attributing to 37% of the world’s total. Next comes South Africa attributing to 30% of the world’s production. Although these countries have a high percentage, other countries such as Cambodia, Madagascar, Canada, Ukraine, Myanmar, Sri Lanka and Thailand produce beautiful zircons which rivals the sparkles of diamonds.
The Colours of Zircon
Most distinct gemstones have a specific colour associated with them: Rubies are red, Tanzanite is blue-ish purple. The Zircon, however, similar to the sapphire, spinel, tourmaline and garnet, have a multitude of colours associated with them. The most popular colours of Zircon are blue, green, brown, yellow, orange and red. Of course, one must not forget the colourless Zircon when talking about the most popular colours of Zircon. Overall the colour adds to the zeal of the zircon.
Zircons also have an evenness of colour similar to that of spinels. The constituent elements, which give gemstones their colour, are dispersed equally within the zircons. This property allows light to travel freely throughout the stone, allowing an aesthetically pleasing view. We call it the zeal of zircon.
Blue Zircon
Blue coloured Zircon is a beast of its own. Almost all blue Zircon arises from radioactive Zircon, which has undergone heat treatment. The initial Zircon, before heat treatment is usually greyish or reddish-brown in colour. These zircons then undergo heat treatment in an oxygen-free environment, which gives them a bright blue colour. If these blue zircons are re-heated in air, their colour has the potential to turn golden-brown. It is essential to be careful; however, as sometimes the heating process turns the zircons colourless.
Colourless Zircon
Colourless zircons, as mentioned before, can arise from the heating of radioactive zircons; however, natural, colourless Zircons exist and are also common. These colourless zircons can be used to rival the beauty of diamonds and were used as imitations in the past. Currently, colourless Zircons are once again rising in popularity for the beauty that they truly possess, rather than their ability to rival diamonds.
Dispersion of Zircons
The high refractive index of zircons is the cause of the intense sparkles. There are three main types of Zircons: High, intermediate, and low type, varying on the extent of radioactive damage to the crystal structure. The more damaged, the less the refraction and refractive index and the less which the stone sparkles. Low type garnets have a refractive index between 1.78 – 1.85. Intermediate Zircons have refractive indices between 1.85 – 1.93; and finally, High type Zircons have a refractive index between 1.92 – 2.01.
Furthermore, Zircons also have a high birefringence. This property means that a single ray of light is enough for the stone to light up like a diamond. This same optical property causes Zircons to possess “doubling of the back facets”. One can see it in the colourless zircon above, where on observation of the facet edges of the back of the stone it seems as if everything is doubled. In reality, there is only one facet edge, whereas when observing through the gemstone, it seems there are two edges.
Conclusion
Overall this article provided a small glimpse into Zircons, but the true essence and Zeal of Zircon can only be seen in real life with it in between your fingers. So grab the opportunity and grab yourself a Zircon.
References:
Gem Society n.d., Zircon, viewed 1 July 2019, <https://www.gemsociety.org/article/zircon-jewelry-and-gemstone-information/>.
GIA n.d., Zircon Description, America, viewed 1 July 2019, <https://www.gia.edu/zircon-description>.
GIA n.d., Zircon Quality Factors, America, viewed 1 July 2019, <https://www.gia.edu/zircon-quality-factorr>.
Map of Australia n.d., Map, Geology.com, viewed 1 July 2019, <https://geology.com/store/wall-maps/political-map-of-australia-lg.jpg>.
Zircon Meaning, Powers and History 2019, Jewels for Me, viewed 1 July 2019, <https://www.jewelsforme.com/gem_and_jewelry_library/zircon>.
Zircon 2019, Gem brokers, viewed 1 July 2019, <http://www.gemsbrokers.org/gemstone/gems_and_gemology/zircon_myths.htm>.