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December

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dec gems

Tanzanite, Zircon, and Turquoise


Tanzanite


The popularity of tanzanite, with its aurora of stunning blues and violets, is well deserved. Demand for it has rocketed in recent years, outstripping sales of all other colored gemstones-with the exception of sapphire. A thousand times rarer than diamond, and with a little over a decade of mine life remaining, tanzanite is the fashion gem of the millennium.  


Just the facts


A key ingredient to tanzanite's success is that it exhibits more shades of blue than a clear midnight sky, due to a phenomenon called pleochroism, whereby different colors are seen in different directions of the gemstone.

 

 

 

 Tanzanites Include:

Pear-Shaped, Round 


Tanzanite

December's Birthstone

Major Sources

Tanzania

Colors Found

Shades of Lilac, Blue, Violet, and Purple as well as Green and fancy colors

Family

Zoisite: Ca2Al3Si3O12(OH)

Hardness

6.5 - 7

Refractive Index

1.69 - 1.70; Biaxial (+)

Specific Gravity

3.35

Crystal System

Orthorhombic

Zircon


Zircon's name is either derived from the Arabic word zarkun, meaning "red," or a combination of the ancient Persian words zar, meaning "gold," and gun, meaning "color." Despite this name, zircon actually occurs in a myriad of colors. 

 

 


Just the Facts


Although zircon's existence predates cubic zirconia by centuries, zircon is often unfairly confused with cubic zirconia, a cheap, man-made diamond substitute. ZWhile zircon may also be used as a diamond substitute, it is valuable in its own right.

 

 

Zircons Include:

Ratanakiri, Champagne, Fancym Tanzanian


Zircon

December's Birthstone

Major Sources

Australia, Burma, Cambodia, Nigeria, Sri Lanka, Tanzania, Thailand & Vietnam

Colors Found

Blue, Green, Honey, Red, White & Yellow

Family

Zircon: ZrSiO4

Hardness

6.5 - 7.5

Refractive Index

1.82 - 2.02; Uniaxial (+)

Specific Gravity

3.93 - 4.73

Crystal System

Tetragonal

Turquoise


The name turquoise is derived from the French pierre turquois, meaning "Turkish Stone." This is because western Europeans mistakenly thought the gem came from Turkey.

 

 

 


Just the facts


Turquoise, a hydrated phosphate of copper and aluminum, is prized as a gemstone whose intense blue color is often mottled with veins of brown limonite or black manganese oxide (commonly known as spider's web turquoise). It is almost always opaque and polished as cabochons, but rare, translucent gems also exist.  

 

 Turquoises Include:

Spider Web, Translucent 


Turquoise

December's Birthstone

Major Sources

China, India, Iran, Mexico, Tibet & USA

Colors Found

Bluish Green & Sky blue

Family

Turquoise: CuAl6(PO4)4(OH)8

Hardness

5 - 6

Refractive Index

1.61 - 1.65

Specific Gravity

2.31 - 2.84

Crystal System

Triclinic (aggregate)

 

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