Zircon Gems and Zircon Stones: A Gemological Marvel
Zircon, often overshadowed by its synthetic counterpart cubic zirconia, is a true gemological wonder that remains relatively unknown to the general public. However, to gemologists and geologists, zircon holds a special place due to its remarkable properties and fascinating history.
Exceptional Refractive Index and Fire
As a gemstone, zircon stands out for its exceptional refractive index, even surpassing renowned gems like sapphire, ruby, spinel, or tanzanite. Its high refractive index contributes to its impressive fire, boasting a dispersion rating nearly comparable to that of diamonds. With a diverse range of colors, including blue, red/orange, honey, and white, top-grade zircon creates stunning and attractive jewelry pieces.
Unusual Properties and Birefringence
Beyond its captivating beauty, zircon exhibits unusual properties that set it apart from other gemstones. Notably, zircon showcases a prominent birefringence or double refractivity, where the difference between its two refractive indices is exceptionally high. This can be observed by looking through the table of a cut zircon, where facet doubling blurs the facet edges. Additionally, zircon boasts remarkable density, surpassing even diamond's density. Only a few minerals, such as hematite and cassiterite, can claim a higher density.
Range of Values and Metamictization
From a gemological standpoint, zircon is highly intriguing due to its large range of values for fundamental properties like refractive index, density, and hardness. The gemological references note zircon's refractive index as ranging from 1.810 to 2.024, density from 3.93 to 4.73, and hardness from 6.5 to 7.5. This broad variation is a result of classifying zircons into high zircons and low zircons. High zircons exhibit values at the upper end of the range, while low zircons have values towards the lower end. Low zircons are typically green in color and lack a crystalline structure due to a process known as metamictization caused by the presence of uranium and thorium in the material. The natural radioactivity disrupts the crystal structure, leading to changes in color and density.
The Oldest Mineral on Earth
Geologists hold a profound interest in zircon because it is the oldest mineral on Earth, with specimens from Australia dating back 4.4 billion years. Considering that the Earth formed 4.56 billion years ago, these ancient zircons represent the earliest record of the Earth's crust. Forming in molten granite as it cooled to form rock, the ancient granitic rock has long eroded away, leaving behind tiny grains of zircon. Thus, zircon holds the distinction of being the oldest known substance on Earth, even predating the moon's formation, which occurred around 4 billion years ago.
A Gemstone Worthy of Every Collection
In conclusion, zircon's exceptional properties, mesmerizing history, and alluring beauty make it a gemstone that deserves a cherished place in every gem collection. So, next time you explore our gemstone collection, take a closer look at the mesmerizing zircon gems, and discover the captivating allure that has captivated gemologists and geologists for centuries. At Sosnagems, we offer a selection of exquisite Zircon gems, ready to be transformed into stunning jewelry pieces that will captivate hearts and stand the test of time.