List of Gemstones | Rare Minerals | Gem stones | Gems » Starlite http://www.all-gemstones.com www.all-gemstones.com    Thu, 06 May 2010 12:29:47 +0000 http://wordpress.org/?v=2.8.6 en hourly 1 Zircon http://www.all-gemstones.com/zircon http://www.all-gemstones.com/zircon#comments Tue, 04 Aug 2009 07:16:14 +0000 admin http://www.all-gemstones.com/?p=1542 Blue Zircon Gemstone Colorless Zircon Gemstone Brown Zircon Rough Golden Brown zircon Rough Orange Red Zircon Gemstone Pink Zircon Gemstone
Refractive Index : 1,984 – 1.925 (+ 0.040 – 0.145)
Optical Characteristic : DR, Uniaxial positive
Specific Gravity : 4.70 (+ 0.03 – 0.80)
Formula : ZrSiO4 +Fe,U,Th,Hf
Crystal System : Tetragonal
Variety/Species : Zircon is classified as high, medium or low type (also called as alpha, beta or gamma type), depending on the extent of structural breakdown. But in trade practice, it is sufficient to identify the stone simply as zircon and specify it according to color.High and Medium – Transparent colorless, blue, yellow to yellow green, brownish green, orange to brown, brownish to orangy red.Low (Metamict) – Transparent brownish to yellowish green with a cloudy texture, more rarely brown or orange.

Hyacinth or Jacinth – Transparent reddish-brown .This term was also applied to hessonite garnet

Jargoon or Jargon – Light yellow to colorless stones from Sri Lanka (Ceylon)

Beccarite – Green

Melichrysos – Yellow

Sparklite – Colorless

Starlite and Stremlite – Blue
Species/Group : Zircon
Birefringence : 0.0 to 0.059
Dispersion : 0.038
Hardness : 6 to 7.5
Toughness : Poor to good
Ultrasonic : Risky
Steam : Risky
UV Long :
Blue – Inert to moderate light blue (LW)Green – Generally Inert

Yellow to Orange Yellow – Inert to moderate yellow to orange (SW to LW)

Red to orange-red – Inert to strong yellow to orange (SW)
Brown – Inert to very weak red (SW)
UV Short : See Above
Pleochroism : 2 colors
Strength : weak
Pleochroism Colors : Blue – Strong blue and brownish yellow to colorlessGreen – Very weak green and yellow green

Orange and brown – weak to moderate purplish brown and brownish yellow

Red – Moderate reddish purple and purplish brown
Heat : May change color
Acids : No reaction
Light : Usually safe
Polish Luster : Vitreous to subadamantine
Fracture : Conchoidal
Fracture Luster : Vitreous to subadamantine
Clarity Type : I to II
Tones : 2-8
Saturations : 1-4
Cause of Color : Color centers
Enhancements : HeatingEffect – Changes color from brown to red, orange, yellow, colorless or blue. Almost all colorless zircons in the market have been heat treated and this treatment is quite stable cannot be detected.

Some stones though revert back to its original color when exposed to sunlight.
Cleavage : Imperfect
Color Range : See Varieties
Transparency : Transparent
Phenomena : Chatoyancy,(rare)
Separations : Zircon from-
Spessartite Garnet : optic character, magnification, spectrum

Andradite Garnet : optic character, magnification, spectrum(possibly)

CZ : doubling, spectrum, SG, magnification, dispersion

YAG : doubling, spectrum, magnification

Sphene : SG, spectrum, optic character

Sphalerite : optic character, magnification, cleavage, diapersion, spectrum(possibly)

Synthetic rutile : doubling (comparative), dispersion, magnification, spectrum, SG (possibly)

GGG : Doubling, spectrum, SG, magnification

Diamond : Doubling, spectrum, SG, magnification, thermal tester

Strontium titanate : Doubling, dispersion, spectrum, SG, magnification
Identifying Characteristics and information
Tiny, white fluffy inclusions, strong twinning or zoning, angular inclusions.Wide variance in SG-4.70 to 3.90. Most gem zircon has high-end properties, often has abraded facet junctions.

High zircon usually 7.5 in hardness;low type around 6. Almost always heat-treated; may fade.

Blue-white phosphorescence
Spectral Data
Strongest line:6535 .Also,6590,6910,6830,6625,6605,6210 many more
Trade Names and Misnomers
Alpha Zircon
Beccartite
Beta Zircon
Ceylon Diamond(M)
Cyrtolite
Gamma Zircon
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