The month of December brings a range of blue birthstones — Turquoise, Tanzanite, Blue Topaz and our subject for today Zircon. Zircon is commonly seen in its colorless and blue state yet, this stone offers a wide range of colors and folklore behind its history.
Zircon gets its name from the Persian word zargon meaning gold-hued. Gold-hued you ask? Zircon can be found in an assortment of earth tones of gold/yellow, browns, green, orange, and red.
5 unique qualities about Zircon:
- HIGH REFRACTIVE INDEX: Zircon is classified as an “over the limit stone” based upon it’s high refractive index. Other stones that have a high refractive index are garnet and diamond.
- HIGH BIREFRINGENCE: All that sparkle you see if due to the gemstone’s high birefringence. As light hits the stone, the light splits and creates a doubling effect hence, MORE SPARKLE. Who doesn’t love a little more sparkle? Often people confuse Zircon in its colorless form for diamonds due to is sparkly appearance.
- HIGH SPECIFIC GRAVITY: Zircon is really dense and heavy for its size.
- RADIOACTIVE: Zircon contains trace amounts of uranium. (Don’t worry it’s not harmful.) Over time the crystal structure begins to break down. Minerals that break down are metamict. Zircon is partly amorphous from the radioactive impurities. Gemologist categorized Zircon into three different categories based upon how much radioactivity has occurred.
- HIGH: Full crystal structure, no breakdown, and exhibit high/normal properties.
- MEDIUM: Mid-range physical properties and some crystal damage to the crystal structure,
- LOW: Extensive damage, low SR, low RI and often the double refraction isn’t evident. The stones are usually green.
- BRITTLE: Zircon is a brittle stone due to the heating process. It’s hardness rates at a 6.5 to a 7.5. It can easily be chipped so jewelry made with Zircon should be worn with caution. These pieces are recommended for special occasions and not everyday wear.
HEATING
Heating is commonly used to add more brilliance to gemstones but heating Zircon can restore the crystalline structure to the stone. This can return the physical properties to a normal/high quality.
The heating method is what transforms Zircon from its natural, earth-toned hues to either its colorless or blue color. There are two forms of heating:
- CHARCOAL: The stones would be surrounded with charcoal for a few hours for the color process to take place.
- AIR: The stones aren’t packed as they are in the charcoal process. The process produces strong yellow, oranges, and red stones.
Stones that didn’t respond to the heating were subject to additional round(s) of processing until the desired color is achieved.
LEGENDS
- It is said the Zircon was used in the hilt of Excalibur
- A recommended amulet for travelers as protection against the plague and injuries.
- When the stone begins to lose its brilliance and grow pale/dull that the plague was near.
- Helped with lightning strikes
- Sleep aide
- Assures cordial reception upon hotel check-in if wearing zircon
Head over to the podcast and hear more in-depth details about Zircon!