ZIRCON
Zircon is a colorful gem with high refraction and fire that’s unfairly confused with cubic zirconia.
Overview
About Zircon
Colorless zircon is known for its brilliance and flashes of multicolored light, called fire. These zircon properties are close enough to the properties of diamond to account for centuries of confusion between the two gems.
Zircon occurs in an array of colors. Its varied palette of yellow, green, red, reddish brown, and blue hues makes it a favorite among collectors as well as informed consumers.
Birthstones & Anniversaries
Zircon is a birthstone for the month of December, along with turquoise and tanzanite.
4.4 billion
Zircon found in Australia is the oldest mineral on earth: 4.4 billion years old.
Metamictization
Zircon sometimes contains traces of uranium, irradiating itself and changing its properties.
Matara
Colorless zircon is called “Matara” zircon after a city in Sri Lanka near where it is mined.
Facts
Mineral: Zircon
Chemistry: ZrSiO4
Color: Blue, red, yellow, orange, brown, green
Refractive index:
High: 1.925 to 1.984 (+/- 0.040)
Medium: 1.875 to 1.905 (+/- 0.030)
Low: 1.810 to 1.815 (+/-0.030)
Birefringence: 0.000 to 0.059 (low to high)
Specific gravity: 3.90 to 4.73
Mohs Hardness: 6 to 7.5 (low to high)
TREATMENTS
There are a number of processes used to alter the color, apparent clarity, or improve the durability of gems.
SYNTHETICS
Some gemstones have synthetic counterparts that have essentially the same chemical, physical, and optical properties, but are grown by man in a laboratory.
IMITATIONS
Any gem can be imitated—sometimes by manmade materials or by natural materials chosen by man to impersonate a particular gem.
WHY WE LOVE THIS GEMSTONE
1
GEOLOGICAL CLOCK
With radioactive trace elements that tick off time, zircon is a geological clock that tells us about the early earth.
2
BRILLIANCE AND FIRE
Zircon has very high luster, refractive indices, and dispersion, giving it lots of brilliance and rainbow flashes of fire.
3
DOUBLE-DOUBLE
Zircon’s pronounced double refraction means you can see twice as many facets and twice as much fire.
QUALITY FACTORS
Among consumers, blue is the most popular color of zircon.
COLOR
The most valuable colors of zircon are blue, bright red, and green.
CLARITY
Zircon is often eye-clean. Gems with noticeable inclusions are less valuable.
CUT
To maximize its brilliance, zircon is most often cut in rounds and ovals.
CARAT WEIGHT
Zircon in fine quality is rare in large sizes. Zircon weighs more than most gems of like size.
ZIRCON QUALITY FACTORS: THE COMPREHENSIVE GUIDE
RESEARCH
Explore sources, gemological research, and the role of gems in history.
Shu-Hong Lin, Yu-Shan Chou, and Kai-Yun Huang , Aug 23, 2022
Nathan Renfro, Ziyin Sun, and Aaron Palke , Jan 28, 2022
RECOMENDED READING
Colored Gemstones: The Antoinette Matlins Buying Guide
Antoinette L. Matlins
Gems of the World
Cally Oldershaw
Zircon
John M. Hanchar and Paul W.O Hoskin
