الألكساندريت
ألكساندرايت القادرة على تغيير لونها هي خدعة طبيعية بينما تظهر باللون الأخضر في أشعة الشمس وباللون الأحمر في ضوء اللمبة.
OVERVIEW
ABOUT AMETRINE
Often described by gem aficionados as “emerald by day, ruby by night,” alexandrite is the very rare color-change variety of the mineral chrysoberyl. Originally discovered in Russia’s Ural Mountains in the 1830s, it’s now found in Sri Lanka, East Africa, and Brazil, but fine material is exceptionally rare and valuable.
1830
The year alexandrite was discovered in Russia’s Ural Mountains.
CZAR ALEXANDER II
Gem’s namesake who emancipated Russia’s serfs and was assassinated in 1881.
580NM
This absorption band allows alexandrite to shift from red to green when viewed under different light sources.
العلاجات
There are a number of processes used to alter the color, apparent clarity, or improve the durability of gems.
SYNTHETICS
Some gemstones have synthetic counterparts that have essentially the same chemical, physical, and optical properties, but are grown by man in a laboratory.
IMITATIONS
Any gem can be imitated—sometimes by manmade materials or by natural materials chosen by man to impersonate a particular gem.
BIRTHSTONES & ANNIVERSARIES
along with pearl and moonstone. Alexandrite is also the gem for the 55th wedding anniversary.
FACTS
Mineral: Chrysoberyl
Chemistry: BeAl2O4
Color: Bluish green in daylight, purplish red in incandescent light
Refractive Index: 1.746 to 1.755
Birefringence: 0.008 to 0.010
Specific Gravity: 3.73
Mohs Hardness: 8.5
WHY WE LOVE THIS GEMSTONE
QUALITY FACTORS
COLOR
Fine alexandrite is green to bluish green in daylight and red to purplish red in incandescent light.
CLARITY
Good quality alexandrite has few inclusions. Rarely, needle-like inclusions create a cat’s-eye.
CUT
Alexandrite is most often available in mixed cuts. Its rarity means it is often cut to save weight.
CARAT WEIGHT
Most cut gems weigh less than one carat. Larger, higher-quality gems rise in price dramatically.
RECOMMENDED READING
RECOMMENDED READING
Antoinette L. Matlins
Colored Gemstones: The Antoinette Matlins Buying Guide
Renée Newman
Gemstone Buying Guide: How to Evaluate, Identify, Select & Care for Colored Gems
Walter Schumann
Gemstones of the World
Antoinette L. Matlins
Colored Gemstones: The Antoinette Matlins Buying Guide
Renée Newman
Gemstone Buying Guide: How to Evaluate, Identify, Select & Care for Colored Gems
Walter Schumann
Gemstones of the World
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