Zircon

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Radiant zircon is the oldest known gemstone, with some crystals dating back 4 billion years, but also perhaps the most misunderstood. Unfortunately, due to the similarity of zircon's name to the lab created diamond simulant cubic zirconia, many people don't realize that zircon is a beautiful, naturally occurring stone with its own merits. Thanks to its tremendous fire and dispersion, it has been considered a less-expensive stand-in for diamond for many years, although zircon gives us many reasons to sing its praises and appreciate it in its own light.

Zircon Polished
Zircon Classification
Common Name Zircon
Species Zircon
Zircon Optical Properties
Transparency Transparent
Dispersion Strength: Moderate Fire Value: 0.038
Refractive Index Over The Limit 1.810-2.024
Birefringence 0.002-0.059
Optic Character Uniaxial
Optic Sign Positive
Polariscope Reaction Doubly Refractive (DR)
Fluorescence SWUV: Variable
LWUV: Variable
CCF Reaction Blue: greenish; Green: sometimes pinkish
Pleochroism Dichroic, (in blue gems) strong blue and colorless; (in red gems) moderate purplish red and reddish brown
Zircon Characteristic Physical Properties
Hardness 6.5-7.5
Streak White
Specific Gravity 3.900-4.730
Toughness Varies
Inclusions Blue and colorless zircons have Type I clarity. Orange, yellow, red and green zircons are Type II clarity stones. Stone might have needles and liquid inclusions. Stones might have abrasions on facet edges. Blue and white stones might show small white billowy inclusions. Low type green stones typically have a lower polish luster and often show strong parallel color zoning or repeated twinning planes, might show hazy appearance when viewed with illumination and angular "skeletal-like" tension fissures.
Luster Bright Vitreous
Stability Fair
Fracture Conchoidal
Cleavage None
Zircon Chemistry & Crystallography
Chemical Name zirconium silicate
Chemical Formula ZrSiO4
Crystal System Tetragonal
Chemistry Classification Silicate

Zircon Colors

  • Blue Zircon Blue
  • Brown Zircon Brown
  • Green Zircon Green
  • Orange Zircon Orange
  • Pink Zircon Pink
  • Red Zircon Red
  • White Zircon White
  • Yellow Zircon Yellow

Zircon Spectra

Zircon Spectra
ZIRCON (Blue)

Color due to heat treatment. The diagnostic absorption line at 653nm; and a weaker one at 662nm; both lines being rather diffuse.

Zircon Spectra
ZIRCON Brown

Color due to uranium and radiation damage. Although dichroism in this zircon is unusually strong, changing from a pronounced brown in the o-ray to a dark green in the e-ray, the spectrum changes very little apart from the width of the dominant strong band in the red centered at 655nm. This indicates it is possibly an intermediate type without a fully crystalline structure.

Zircon Spectra
ZIRCON Brown

Color due to uranium and radiation damage.This large dark orange brown zircon of 11cts. from Sri - Lanka displays most of the absorption lines associated with fully crystalline high type material. However the dark orange brown color absorbs strongly in the violet - blue areas making resolution of the lines there difficult. The diagnostic lines at 653nm. and 661nm. are seen at their strongest when a polarizing filter is used to locate the ordinary ray.

Zircon Spectra
ZIRCON.  

Color due to uranium. This light brown Sri-Lankan zircon shows very little apart from the dominant line in the red at 653nm. and the faint 661nm. alongside

Zircon Spectra
ZIRCON. (ε ray)

Here we see the lines at 653nm. and 661nm. become two lines of equal width and intensity with other lines also appearing. A very faint indication of the two lines at 615nm. and 621nm. can just be seen

Zircon Spectra
ZIRCON. (ε ray)

Color due to uranium and structure changes. A weak and difficult to see fuzzy band from 650nm. to 662nm. and indistinct images of other lines suggests this could be an intermediate type zircon

Zircon Spectra
ZIRCON. (ε ray)

Color due to uranium. The typical lines at 653nm. and 660/662nm. are less distinct

Zircon Spectra
ZIRCON. (unpolarized)

Color due to uranium. The original color of this zircon from Myanmar was a bright greenish yellow. After heat treatment to about 900'C in an attempt to produce a deep violet blue color the aborted experiment produced this almost colorless stone which is not unlike a cape series diamond of low color grade. However, the strong sharp spectrum associated with zircons from this source remained intact as seen here.

Zircon Spectra
ZIRCON (ω ray)

Color due to uranium. The spectroscope here reveals the diagnostic line at 653nm. which, seen here in the o ray, is strong and about 4nm. wide. This is accompanied by the two faint and narrow lines on the long wave side at 660/662nm.These last two lines are usually only resolved by a small hand spectroscope as a single line at 661nm. Other faint lines are seen in the blue and green

Zircon Spectra
ZIRCON (ω ray

Color due to uranium and structural changes. A weak fuzzy band from 650nm. to 662nm. and indistinct images of other lines suggests this could be an intermediate type zircon

Zircon Spectra
ZIRCON (ω ray)

Color due to uranium. Red zircons generally do not show a strong pattern of absorption lines compared to some other colors of zircon. The o-ray chosen here shows the dominant line at 653nm. at its strongest, but the normally strong line at 589nm. is but a weak smudge. Only vague images of the two lines at 484nm and 460 can be seen in the blue. Some red zircons do not display any lines at all

Zircon Spectra
ZIRCON (ω ray)

Color due to uranium. A line at 653nm. becomes sharper and stronger as an indication of the o-ray together with the weaker lines alongside at 660/662nm. Various other fine lines appear throughout the spectrum but are too weak and narrow to be captured in this image

Zircon Spectra
ZIRCON

Color due to uranium. Dark red zircons like many red stones often have a brownish overtone and do not transmit well in the deep blue-violet area of the spectrum. In some, unlike most zircons, there are no obvious lines to be seen not even the usual diagnostic line at 653nm. On close inspection only a few vague shadows can be detected about 590nm 520 nm. and 500nm. close to where some prominent lines may be seen in most other colors of zircon

Zircon Spectra
ZIRCON. (ε ray)

Color due to uranium. As the e ray is polarized, although the stone appears the same, the spectrum changes in that the lines at 615nm. And 621nm. are present and stronger.

Zircon Spectra
ZIRCON (ω ray)

Color due to uranium. However, the indication of the o ray is seen in the spectrum by the absence of the two lines at 615nm. and 621nm. in the orange. Note in the unpolarized spectrum above these two lines are just visible but are very faint. Slight variations also occur in the strength of various other lines.

Jewelry Television acknowledges the significant scientific contributions of John S Harris, FGA to the study of gemstone spectra and with deep appreciation to him, acknowledges the use of his images and related notes about gemstones and their spectra in the educational materials on this website.

Alternate Names

High Zircon, Medium Zircon, Low Zircon Or Metamict, Hyacinth, Jacinth, Jargoon Or Jargon, Beccarite, Melichrysos, Sparklite, Starlite, Stremlite

Countries of Origin

Tanzania, United Republic Of; Colombia; Myanmar; Cambodia; Sri Lanka; Madagascar; Thailand; French Polynesia; India; Canada; Mozambique; Pakistan; Unknown; Malawi; Norway; China; Russian Federation (the); Brazil; Mexico; Australia; Nigeria; United Kingdom of Great Britain and Northern Ireland (the)

History

Zircon is a beautiful, natural gemstone with a high refractive index and strong dispersion, a gemological way of saying well-cut zircon is actively brilliant and full of fire! What's more, it is available in a broad color range - yellow, brown, orange, red, violet, green, blue, and colorless. When a vast supply of blue zircon hit the world market in the 1920s, George Kunz became suspicious. Before that, most zircon were brown to green. George suspected treatment. Sure enough, a little investigation revealed that the lovely blue stones were heat treated. Interestingly, when the truth was revealed, the stone's popularity remained steady. Why? Savvy consumers loved the blue of the stone so much, they simply didn't care. Zircon is a wearable stone (7 ½ on the hardness scale) whose clear, compelling colors make it as popular today as it was in the 1920s.

Care

Don't confuse zircon with cubic zirconia. Despite their close names, they are unrelated.

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Related Videos

More About Zircon

Marbode, in the 11th century, wrote that zircon was an excellent amulet for travelers and would ensure safety, rest and a warm welcome at the end of a journey. Some later cultures attributed the stone with lending prudence in practical things (linked thereby to financial success), and providing protection from lightning, What do we believe about zircon? We believe that it is lovely. Slow down. Take your time. Enjoy a look at each of those memorable colors.

Zircon Gemstone

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Tim Matthews

Author

Tim Matthews

Tim Matthews is President and Chief Executive Officer of Jewelry Television® (JTV), as well as a member of the company's Board of Directors. He oversees and leads all aspects of the company's powerful omni-digital retail platform that uniquely specializes in fine jewelry and gemstones. His passion for business and gemstones has led him to become a recognized expert in the field of gemology. He is a life member of the Gemmological Association of Great Britain (Gem-A) and has earned Gem-A's highest degrees, the Gemmology (FGA) and Diamond (DGA) diplomas. He is also a Graduate Gemologist (GG) of the Gemological Institute of America (GIA) and has also completed GIA's Graduate Diplomas in Diamonds, Colored Stones and Pearls. Under his leadership, JTV has become the leader in the sourcing and selling of color gemstones and jewelry.

This page was created on June 27, 2014.

This page was last edited on October 24, 2019.