search
  • Sign In
    Sign Up
  • English speaking customer support only

    1-800-464-1640

  • Change Language
  • USD
By Gavin Clarke Reviewed By Andreas Zabczyk Nov 13, 2009 Updated Aug 21, 2017

About Green Zircon, Low Zircon & Metamict Zircon

Zircon is an unusual gemstone on a number of counts. Often confused with cubic zirconia, a made-made synthetic diamond substitute, natural zircon is actually the oldest mineral on Earth. In fact, according to samples found in Australia, researchers discovered that the material dates back from more than 4.4 billion years ago, even older than the moon itself. Zircon is of such important interest to geoscientists, it has spawned its own discipline known as 'zirconology'.

Another unusual thing about zircon is that its gemological properties exhibit very wide ranges. For example, if you look at zircon's values for hardness, specific gravity (density) and refractive index, you'll notice that the ranges are very wide. Gemological resources list zircon as having a hardness of 6.5 to 7.5; a density of 3.93 to 4.73; and a refractive index of 1.810 to 2.024.

The reason for the wide variation is that there is so-called low zircon and high zircon, with the high zircon having values at the top of the range. Low zircon - that with lower density, hardness and refractive index - forms as a result of a unique process associated with the presence of uranium and thorium. The natural radioactivity of these elements disrupts the crystal structure, thus causing changes in color and density. These changes take place over a long period of time through a process known as metamictization.

This so-called metamict zircon is always green or brown in color. Though externally it looks much like normal zircon, internally it has lost its crystal structure and has become isotropic glass. Though the metamictization process lowers a mineral's refractive index, hardness and specific gravity, it does not, curiously, affect the mineral's brilliance, dispersion or fire.

The green metamict zircon is quite rare and is prized by collectors. Some samples still emit low levels of radiation. The loss of crystal structure often makes the metamict specimens darker and cloudier, and some samples may be heated to lighten the color. Experiments have shown that prolonged heating can result in substantial recrystallization. Of all the many different varieties of colored stones available today, zircon is prized for its remarkable brilliance and fire.

Sri Lanka is the best known source for green metamict zircon, although low zircon specimens are also found in Burma, and may also exist in other well-known zircon deposits located throughout Cambodia. Cambodia and Southeast Asia are the important sources for fine zircon today, particularly when it comes to material suitable for the making of heat-treated blue zircon, which has become one of the most popular blue gemstones choices over recent years.

STAY IN TOUCH
*You're signing up to receive GemSelect promotional email.
Partners and Trust Payment options

Switch to Mobile Version

Privacy Notice © 2005-2023 GemSelect.com all rights reserved.

Reproduction (text or graphics) without the express written consent of GemSelect.com (SETT Company Ltd.) is strictly prohibited.

1105

More Shapes
Popular Gemstones
  • Sapphire
  • Emerald
  • Ruby
  • Aquamarine
  • Zircon
  • Opal
  • Topaz
  • Tourmaline
  • Garnet
  • Amethyst
  • Citrine
  • Tanzanite
All Gemstones (145)
A B C D E F G H I J K L M N O P Q R S T V Z
  • Actinolite Cat's Eye
  • Agate
  • Agate Geode
  • Almandine Garnet
  • Amazonite
  • Amethyst
  • Amethyst Geode Slice
  • Ametrine
  • Ammolite
  • Andalusite
  • Andesine Labradorite
  • Apatite
  • Aquamarine
  • Aventurine
  • Azotic Topaz
  • Azurite
  • Black Opal
  • Bloodstone
  • Boulder Opal
  • Carnelian
  • Cat's Eye Apatite
  • Cat's Eye Aquamarine
  • Cat's Eye Gemstones
  • Cat's Eye Moonstone
  • Cat's Eye Opal
  • Cat's Eye Scapolite
  • Chalcedony
  • Charoite
  • Chocolate Opal
  • Chrome Diopside
  • Chrysoberyl
  • Chrysoberyl Cat's Eye
  • Chrysocolla
  • Chrysoprase
  • Citrine
  • Color Change Gemstones
  • Color-Change Diaspore
  • Color-Change Fluorite
  • Color-Change Garnet
  • Coral
  • Demantoid Garnet
  • Dendritic Agate
  • Diamond
  • Druzy Amethyst
  • Druzy Azurite
  • Druzy Citrine
  • Druzy Variscite
  • Emerald
  • Enstatite
  • Fire Agate
  • Fire Opal
  • Fluorite
  • Fossil Coral
  • Garnet
  • Golden Beryl
  • Grandidierite
  • Grossularite Garnet
  • Hawk's Eye
  • Hematite
  • Hemimorphite
  • Hemimorphite Druzy
  • Hessonite Garnet
  • Howlite
  • Idocrase
  • Imperial Topaz
  • Iolite
  • Jade Gemstones
  • Jadeite
  • Jasper
  • Kornerupine
  • Kunzite
  • Kyanite
  • Labradorite
  • Lapis Lazuli
  • Larimar
  • Malachite
  • Malaya Garnet
  • Mali Garnet
  • Maw-Sit-Sit
  • Moonstone
  • Morganite
  • Mother Of Pearl
  • Mystic Quartz
  • Mystic Topaz
  • Nuummite
  • Obsidian
  • Onyx
  • Opal
  • Opal Doublet
  • Opal In Matrix
  • Pearl
  • Peridot
  • Pietersite
  • Prehnite
  • Pyrite
  • Pyrope Garnet
  • Quartz
  • Quartz Cat's Eye
  • Quartz With Hedenbergite
  • Quartz With Marcasite
  • Rainbow Moonstone
  • Rainbow Pyrite
  • Rhodochrosite
  • Rhodolite Garnet
  • Rhodonite
  • Rose Quartz
  • Rubellite Tourmaline
  • Ruby
  • Ruby In Fuchsite
  • Ruby-Zoisite
  • Rutile Quartz
  • Sapphire
  • Scapolite
  • Scolecite
  • Seraphinite
  • Serpentine
  • Sillimanite
  • Sillimanite Cat's Eye
  • Smithsonite
  • Smoky Quartz
  • Snowflake Obsidian
  • Sodalite
  • Spectrolite
  • Spessartite Garnet
  • Sphalerite
  • Sphene
  • Spinel
  • Star Diopside
  • Star Garnet
  • Star Gemstones
  • Star Moonstone
  • Star Rose Quartz
  • Star Ruby
  • Star Sapphire
  • Strawberry Quartz
  • Sunstone
  • Tanzanite
  • Tiger's Eye
  • Tiger's Eye Matrix
  • Topaz
  • Tourmaline
  • Tsavorite Garnet
  • Turquoise
  • Variscite
  • Zircon
Main Categories
  • New Arrivals
  • Gemstone Lots
  • Calibrated Gemstones
  • Gemstones By Piece
  • Top Grade Gems
  • Matching Pairs
  • Cabochon Gemstones
  • Drilled Gems, Briolettes and Beads
  • Birthstones
  • Gemstone Carvings
  • Fancy Gemstones
  • Star Gemstones
  • Unheated Sapphire
English speaking customer support only

Toll Free - USA & Canada only:
1-800-464-1640

International:
+66-39609697

Save Money
No shipping Fees for Additional Items!
$8.90 Worldwide Shipping

Update Translation
 
Current Value
New Value
GemSelect Gemstones
X Close Window
Colored Gemstones
X Close Window
Colored Gemstones
X Close Window
Colored Gemstones
Size and Weight

Gems are always measured in Millimeter (mm)

Dimensions are given as;
length x width x depth,
except for round stones which are;
diameter x depth

Select gems by size, not by weight!
Gem varieties vary in density, so carat weight is not a good indication of size

Note: 1ct = 0.2g

Size Comparison Chart