In stores, we are often inundated by a flood of gold and silver jewellery which shine due to their clear or variously coloured stones called zircons. In most cases however, these are actually cubic zirconias. In practice, the names of these two stones with a similar sounding name are often interchanged, but in reality they are two different stones that have very different origins, composition and value.
Zircon: the oldest gemstone on Earth
It might be surprising to some, but the oldest mineral on Earth is zirconium with the chemical composition of zirconium silicate (ZrSiO4). The first specimen of it was found in Australia and is estimated to be 4.4 billion years old. Zircon enjoyed considerable popularity in jewellery in the 1920s. The colour range in which zircon occurs in nature is vast. The most common zircons come in yellow, red and brown shades and more rarely we might also encounter colourless and blue varieties. Due to their high brilliance, colourless zircons resemble diamonds, but in contrast to them, they are characterized by birefringence and have a hardness of 7.5 on the Mohs scale (compared to 10 for a diamond).
Cubic zirconia: the most successful imitation of a diamond
For many centuries, scientists have sought to create the closest possible replacement to diamonds. When the process of producing cubic zirconia was discovered in the 1970s, zirconia production spread throughout the world and became the most commonly used imitation diamond. The abbreviation CZ (cubic zirconia) has been adopted on the market and in addition to the colourless variety, cubic zirconias can have almost any colour you can imagine. Although cubic zirconias have a little less brilliance and conversely more "fire" (colour sparkle) than diamonds, at first glance they are indistinguishable from diamonds. However, if you are buying jewellery and choosing between a diamond and cubic zirconia, it is good to keep in mind that zirconia has a lower durability. After a zirconia has been worn for a while, it loses its luster, while a diamond still shines like new. This is because zirconia is 8.5 degrees on the hardness scale and thus softer than a diamond.
*diamond left, zirconia right
Zircon vs. zirconia
Although natural zircon could be considered an alternative to a diamond, it is a distinctive gemstone that is far more valuable than cubic zirconia. It should be said however that setting natural zircon into jewellery is not such a common phenomenon today. If a merchant states that a piece of jewellery is fitted with zircons, it is often cubic zirconia. So that said, when buying jewellery, we recommend that you turn to a seller that you trust who will give you correct information rather than misleading you.