Tsavorite Alternate Birthstone for May A Variety of Grossular Garnet Tsavorite is a variety of green grossular garnet. It is one of the newest of the precious gemstones discovered in 1967. It occurs in shades of green ranging from spring-like pale green to intensely bluish green to deep forest green. Often compared to emerald, tsavorite is a superior choice in many ways. Tsavorite is not only more durable than emeralds, it is also more highly dispersive and refractive. Tsavorites are not treated with oils or resins as emeralds typically are.

 

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Chatelaine's Antiques & Appraisals Magazine > Jewelry > Expert Tip: Gemstones > Alexandrite

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Alexandrite
June Birthstone
Traditional Gem: Alexandrite
Modern Gem: Pearl, Moonstone

ALEXANDRITE, the color changing variety of chrysoberyl 
VARIETY INFORMATION:
VARIETY OF: Chrysoberyl ,
BeAl2O4
USES: Gemstone. 
BIRTHSTONE FOR: June 
COLOR: varies from red to green. 
INDEX OF REFRACTION: 1.745 - 1.757 
BIREFRINGENCE: 0.009 
HARDNESS: 8.5 
CLEAVAGE: good in one direction, imperfect in another 
CRYSTAL SYSTEM: orthorhombic 
Pleochroic: strongly 
We sell natural alexandrite mineral Specimens 
For jewelry, visit our Affiliates 
Alexandrite is named for the former czar of Russia, Alexander II, and was first discovered in the Ural Mountains of Russia, supposedly on the day of his birth. Chromium gives alexandrite its color and while, in most minerals, a trace element like chromium would provide only one color to the mineral, in alexandrite it gives it two! Coloring agents are dependent on the wavelength of light and the chemical bonds in the crystal to determine the color that they will cause. An element like copper, in normal light, can cause a green color in malachite and a blue color in azurite, it all depends on the character of the chemical bonding. In a single specimen of alexandrite, the chromium is in such a balanced situation that the color of the specimen depends on the character of light that hits the crystal. If the light is natural sunlight or fluorescent light, the crystal will be green; however, if the light is incandescent light from a common indoor light bulb, then the crystal will appear red. 
Synthetic corundums spiked with trace elements that yield an alexandrite-like color change are sold as alexandrite on the gemstone market. These stones have a red-violet, near-amethyst color in incandescent light and a blue-violet color in daylight. They are far cheaper than natural alexandrites, which are some of the rarest and most expensive of gemstones.

 

Gemstone Composition Crystal System Density Hardness Refractive index Treatments
Alexandrite BeAl2O4          

 

Alexandrite is often confused with:

 

 

 



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