Although Zircon has not historically been a well known gemstone it is now gaining popularity. Many people mistake it for cubic zirconia, a synthetic material, but the two are quite different. True zircon gems occur naturally.
White zircon has been one of the most significant diamond substitutes because of its high dispersion and refractive index. Because of this it was often marketed under the misleading trade name of ‘matura diamond’.
A great range of colors occur in zircon. Currently, the most popular zircon is blue which usually occurs with green pleochroism and can result in gorgeous teal-like colors. Zircon is also remarkably dense and exhibits a pronounced level of birefringence which makes it display facet-doubling.
There is also the blue zircon variation which is one of the traditional modern birthstones for December. Its prominence has led to the emergence of the discipline of ‘zirconology’. Zircon is the oldest mineral on Earth with samples of it found in Australia dating back to 4.4 billion years ago.
Even though it is white in its purest form, zircon can also occur in yellow, orange, red, green, blue, violet, brown and combinations in between. Some scientists have discovered that zircon contains trace elements of uranium and thorium lending a wide range of variations in its physical properties.
Classified as low, medium and high depending on the presence of its optical properties, lower zircon has higher traces of radioactive uranium and thorium while higher zircon has the least of those 2 elements.
As the oldest known mineral on earth, zircon was formed 4 billion years ago which makes it older than the moon. Most of its deposits are found in the sand, silt and gravel that remains in riverbeds or deltas. Sri Lanka is the best known source for the ‘low’ zircon, followed by countries including Brazil, Korea, Madagascar, Mozambique, Nigeria, Tanzania, Thailand and Vietnam.