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The Gemstone Alexandrite
Alexandrite is the highly regarded color changing variety of
Chrysoberyl
. The color of Alexandrite changes under different lighting conditions. If viewed in daylight, its color is greenish blue to dark yellow-green. If viewed in incandescent or candle light, its color is pink to red. Alexandrite is a very rare and highly valuable gemstone, and until recently was extremely difficult to obtain due to its rarity. However, new sources in Brazil and Tanzania have made this gemstone available and more mainstream on the gemstone market.
Chemical Formula
BeAl
2
O
4
Color
Blue, Red, Green, Yellow, Pink, Purple, Gray, Multicolored
Hardness
8.5
Crystal System
Orthorhombic
Refractive Index
1.744 - 1.755
SG
3.5 - 3.8
Transparency
Transparent
to nearly
opaque
Double Refraction
.009
Luster
Vitreous
Cleavage
1,1 ; 3,2. Often exhibits
parting
along
twinned
crystals.
Mineral Class
Chrysoberyl
Alexandrite
AUCTIONS
ALL ABOUT
Alexandrite was first discovered in Russia in the early 1800's. It was named in honor of Alexandar Nicholavich, who was later to become the Russian Czar Alexander II. Legend has it that the gemstone was discovered on the future Czar's birthday and named in his honor, though the factual nature of this is disputed.
The unique color change habit of Alexandrite is caused by slight
impurities
of the
element
chromium. The most desirable colors of Alexandrite are those that show a clearly visible pure hue color change, such as a pure green/blue in daylight to a pure red in incandescent light.
In addition to its color-changing habit, Alexandrite is a
pleochroic
gem, showing different color intensity when viewed at different angles. This factor must be taken into account when cutting Alexandrite gemstones. Alexandrite exhibiting
chatoyancy
does exist but is very rare, thus Alexandrite
Cat's eye
is rarely available.
USES
Alexandrite
is a rare and exquisite gemstone with outstanding color changing properties, and is most often faceted into round and cushion cuts that can bring out the best in its color. In jewelry, Alexandrite is used as rings and pendant centerpieces. Alexandrite in large sizes is extremely rare and valuable; most Alexandrite available is 2
carat
s or less.
FALSE NAMES
Alexandrine
- Synthetic, lab grown Alexandrite simulant.
Alexandrite Sapphire
- Synonym of
Color-change Sapphire
.
Alexandrite Garnet
- Synonym of
Color-change Garnet
.
Blue Alexandrite
- Synonym of
Color-change Sapphire
.
Czochralski Alexandrite
- Synthetic, lab grown Alexandrite simulant.
Alexandrite
TREATMENTS AND ENHANCEMENTS
Alexandrite gemstones are not treated or enhanced. A synthetic form of Alexandrite exists, and it can be difficult to distinguish natural and synthetic Alexandrite from each other. Most synthetic Alexandrite is in fact synthetic
Corundum
or synthetic
Spinel
with added vanadium or chromium to induce the color-change habit.
Alexandrite
SOURCES
Alexandrite was originally discovered in the Sanarka River in the southern Ural Mountains of Russia. However, the Russian deposits have long since been exhausted, and Russian sources of Alexandrite are near impossible to obtain. Small deposits were subsequently found in Sri Lanka (Ceylon), and until the 1980's these were the only two sources of this rare gemstone. Since then, new deposits have been discovered in Brazil, Tanzania, and Madagascar, with the Brazilian sources being the most significant.
SIMILAR GEMSTONES
The only other color changing gemstones are
Color-change Garnet
and
Color-change Sapphire
. Alexandrite is softer than Sapphire and harder then Garnet.
Alexandrite
PHOTOS
[Click photos for more details]
Alexandrite
IN THE ROUGH PHOTOS
[Click photos for more details]
ADDITIONAL RESOURCES
The mineral Chrysoberyl
The gemstone Chrysoberyl
DISCUSSION
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and ask the experts!
PAGE SPONSOR
The
Rare Gem LLC
is a New York based father-and-son company, with 40 years of experience buying and selling natural alexandrites within the gem trade. For the first time, they are offering just a few of their most prized V
espertine Alexandrites
to the public - shop now before they're gone for good.
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