Of all the popular blue gemstones, none can match the fire and brilliance of blue zircon. Zircon has the unique distinction of being the oldest mineral on earth at 4.4 billion years. Its icy blue hues and festive sparkle make it our favorite December birthstone, yet it is still relatively unknown to those outside the world of gem collecting. Below, we explore why blue zircon is such an exceptional gemstone.
Blue zircon is erroneously thought to be related to cubic zirconia, a synthetic diamond simulant. In fact, zircon is a naturally occurring gemstone also known by its mineral name zirconium silicate. In addition to blue, zircon can be red, yellow, orange, green, brown, and colorless. Blue zircon is created through heat treating brown zircon, although only certain physical structures of brown zircon can be transformed into blue. Blue zircon is pleochroic, meaning it can appear to be different colors when viewed from various angles. Often you will see shades of sea green in an otherwise cerulean blue zircon.
Zircon’s exceptional light dispersion, or fire, is due to a strong double refraction (birefringence). This causes white light to split into a spectrum of colors, producing the rainbow effect most people are familiar with. Though it is slightly softer than its blue counterpart, the sapphire, ranging 6 to 7.5 on the Mohs hardness scale, this brilliance and fire make it just as desirable. Beautiful specimens of zircon can be found in Cambodia, Sri Lanka, Thailand, Myanmar, and Australia.
Zircon is susceptible to radiation, and can contain trace elements of uranium. This quality causes zircon to record important geological events, allowing scientists to learn more about the formation of the earth, simply by studying the gem. Depending on the amount of radiation, the gemstone’s crystal structure will break down and it will lose its desirable properties. Because of that fact, all of the zircon used in jewelry has little to no radiation.
In the Middle Ages, zircon was believed to have the power to do everything from banishing evil to inducing restful sleep. It was also believed to bring prosperity and honor to whomever possessed it. Blue zircon was popular in the Victorian Era, and colorless zircon was used in the early 1900’s as a diamond substitute. Celebrated gemologist George Kunz was a big fan of zircon and tried to market it under the name “starlite” to express its fiery qualities. However the nickname never caught on, and zircon stayed out of the mainstream jewelry market.
Blue zircon can dull with prolonged exposure to sunlight, but the color can be restored with heat treatment. When caring for your blue zircon jewelry, avoid ultrasonic cleaners and harsh chemicals, and use soft polishing cloths or tooth brushes to avoid chipping the gem. With basic care, your blue zircon jewelry can be passed down for generations to come.