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Zircon is a colorful gem with high refraction and fire that’s unfairly confused with cubic zirconia.

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Cushion Cut

This 21.05-ct. cushion cut, orange zircon is from Tanzania.

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Fall Color

This gem displays a warm autumnal reddish brown.

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Seeing Double

Zircon’s strong double refraction causes double images of facets.

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Cinnamon Brown

Like this rare untreated 48.50-ct. crystal, zircon is often brownish.

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Pointed Cap

Zircon crystals are often four sided and capped with pyramid shapes.

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Ubiquitous Gem

Zircon crystals grow in many different types of rock.

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About Zircon

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.

Zircon Description

Zircon History and Lore

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.


Zircon sometimes contains traces of uranium, irradiating itself and changing its properties.


Colorless zircon is called “Matara” zircon after a city in Sri Lanka near where it is mined.


  • 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)


There are a number of processes used to alter the color, apparent clarity, or improve the durability of gems.

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Some gemstones have synthetic counterparts that have essentially the same chemical, physical, and optical properties, but are grown by man in a laboratory.

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Any gem can be imitated—sometimes by manmade materials or by natural materials chosen by man to impersonate a particular gem.

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gem love

Why We Love This Gemstone

Geological Clock

With radioactive trace elements that tick off time, zircon is a geological clock that tells us about the early earth.

Brilliance and Fire

Zircon has very high luster, refractive indices, and dispersion, giving it lots of brilliance and rainbow flashes of fire.


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.


quality factors

The most valuable colors of zircon are blue, bright red, and green.


quality factors

Zircon is often eye-clean. Gems with noticeable inclusions are less valuable.


quality factors

To maximize its brilliance, zircon is most often cut in rounds and ovals.

Carat Weight

quality factors

Zircon in fine quality is rare in large sizes. Zircon weighs more than most gems of like size.

Zircon Quality Factors: The Comprehensive Guide


Explore sources, gemological research, and the role of gems in history.

Faceted blue zircons

Reversible Color Modification of Blue Zircon by Long-Wave Ultraviolet Radiation

Nathan D. Renfro , Nov 7, 2016 Read Article
Five zircon samples studied for radioactive degradation of crystal structure.

Chemical Analysis of Zircon

Akhil Sehgal , Jul 31, 2015 Read Article
Dense cluster of zircon inclusions in Ethiopian sapphire

Zircon Cluster in Ethiopian Sapphire

Charuwan Khowpong , Feb 1, 2019 Read Article
Short-wave UV exposure’s effect on zircon color

Tenebrescent Zircon

Ratima Suthiyuth , Jul 25, 2014 Read Article