 |
Zircon is a natural gemstone, not to be confused with cubic zirconia, a cheap synthetic diamond simulant. Natural zircon, like spinel, is one of those gemstones which is highly regarded by gem dealers and collectors, but is not well known in the commercial jewelry market.
As a gemstone, zircon is noted for its high refractive index and excellent fire. In fact zircon has a higher refractive index than sapphire, ruby, spinel or tanzanite. Zircon also has impressive fire, with a dispersion rating nearly as high as diamond. Zircon is found in a range of colors, including blue, red/orange, honey and white. High quality zircon makes impressive jewelry.
 |
 |
 |
Blue is the most popular zircon color and fine blue zircon has more sparkle than any other blue stone in the gemstone world. The zircon blues range from light to medium blue, sometimes with a slight greenish secondary hue. Blue zircon is produced by low temperature heating, but only the Cambodian and Burmese zircon will turn blue when heated. Prices depend on color saturation, clarity and size.
 |
In addition to its obvious beauty, zircon has some unusual properties. For example, it has very pronounced birefringence or double refractivity, where the difference between the two refractive indices is unusually high. This can be observed with the naked eye when you look down through the table of a cut zircon: you will observe facet doubling that makes the facet edges looked blurred. Zircon is also a remarkably dense mineral, with a density about 50% higher than diamond. Only a few minerals such as hematite and cuprite haver a higher density.
Gemologically, zircon is a zirconium silicate by chemical composition, with a hardness of 7.5 on the Mohs scale. It is suitable for all kinds of jewelry, though protective settings are recommended for rings.
The traditional sources for zircon are Sri Lanka, Burma and Cambodia. These days most of the fine blue zircon comes from Cambodia. But Tanzania has become an important new source for red, orange and honey zircon.
Compared to sapphire or spinel, zircon is very affordable, and high quality specimens can be found in larger sizes as well. Since zircon is such a dense material, it is always a good idea to check the size as well as the carat weight when buying zircon.
