Iroishi Checker
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ReferenceREFERENCE
Alexandrite (Natural)Contribute a photo

Alexandrite (Natural)

アレキサンドライト（天然） · あれきさんどらいと
NaturalColor-Change
Gemological dataPROPERTIES
Hardness8.5
Specific gravity3.68-3.78
Refractive index1.741-1.760
Crystal system斜方晶系（クリソベリル）
Color rangeCOLOR RANGE

Daylight: blue-green to forest green. Incandescent (or candlelight): raspberry red to purplish red. Russian Ural material shows the strongest, cleanest change; Brazilian and Sri Lankan stones often shift to a softer brownish red.

UV responseFLUORESCENCE
Long-wave
365 nm
Weak to moderate in chromium-rich stones
Short-wave
254 nm
Weak red
Typical inclusionsINCLUSIONS
  • nclusions
  • Needles and silk
  • nclusions
  • nclusions (rutile, apatite)
Optical characterOPTICAL TRAITS
  • Doubly refractive, biaxial positive
  • Strong trichroism: green, orange, red
What to look forID POINTS
  1. 01Sharp, complete color change between daylight and incandescent is the headline test
  2. 02Three-color through a dichroscope distinguishes alexandrite from color-change garnet and synthetic corundum imitations
  3. 03Curved bands or unusually clean material suggests Czochralski synthetic
  4. 04Flux synthetics may show wispy veils and platinum platelets
Stones it gets mistaken forSIMILAR STONES
Color Change Sapphire (Natural)
Color Change Sapphire (Natural)
カラーチェンジサファイア（天然）
アレキは緑→赤に劇的変色、カラーチェンジサファイアは青→紫の範囲。UV蛍光と屈折率で区別。
Color Change Garnet
Color Change Garnet
カラーチェンジガーネット
アレキは変色が鮮明、ガーネットはあいまい。屈折率と比重で区別可能。
Care & handlingCARE
  • Durable for daily wear
  • Safe to ultrasonic and steam unless heavily fractured
  • Worth photographing under both daylight and tungsten — color shift is the identity
Market notesMARKET
PRICE RANGE

From $2,000/ct for commercial material with weak change up to $100,000+/ct for fine Russian Ural stones with strong change and clean clarity.

Note: Color change strength is the dominant value driver — over 60% change is considered fine. Carat-for-carat, fine alexandrite over 3 ct exceeds top ruby and sapphire prices. Synthetic alexandrite (Czochralski and flux) is common; verify with a lab report.

BackgroundBACKGROUND

Alexandrite is chrysoberyl (BeAl₂O₄) trace-doped with chromium, which sits in a crystal field where green and red transmission are nearly balanced — small shifts in light source produce a dramatic color change. Mohs 8.5 with no makes it surprisingly tough for an extremely rare collector stone.

Origin & historyORIGIN & HISTORY

Origins

Discovered in 1830 in the Ural Mountains of Russia. Ural material remains the benchmark and is essentially mined out. Brazil's Hematita mine produced excellent material in the late 1980s. Sri Lanka, Tanzania (Tunduru), and India contribute most of today's supply, though fine color-change material remains exceptionally rare.

History

Discovered on April 29, 1834 — the day of the future Tsar Alexander II's coming of age — and named in his honor. The green and red echoed the colors of Imperial Russia, and the stone became a symbol of the empire. Modern lapidaries call top alexandrite 'emerald by day, ruby by night.'

Lore & symbolism

June's birthstone (modern, alongside pearl and moonstone). Said to bring luck and balance, and to strengthen intuition. The 55th wedding anniversary gem.

OBSERVATION TOOLS · 5 ITEMS

Tools to confirm this stone

Tools that help confirm Alexandrite (Natural). Tap any item to jump to the matching section on the gem tools page.

References
最終確認日
2026年4月28日
参 考 文 献

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