Alexandrite
Chrysoberyl that is green by day and red by candlelight.
- Family
- Chrysoberyl
- Formula
- BeAl₂O₄
- Mohs
- 8.5
- System
- Orthorhombic
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Science
Alexandrite is chrysoberyl with chromium. The chromium absorbs light such that the stone transmits green and red equally; daylight, rich in green, shows it green, while incandescent light shows it red. It requires beryllium and chromium together, as emerald does, which is why it is so rare.
- Mineral
- Chrysoberyl (variety)
- Formula
- BeAl₂O₄
- Crystal system
- Orthorhombic
- Mohs hardness
- 8.5
- Specific gravity
- 3.73
- Refractive index
- 1.746 to 1.755
- Lustre
- Vitreous
- Colours
- Green, Red, Purple
- Birthstone
- June
Composition
BeAl₂O₄. Made of Beryllium, Aluminium, Oxygen, with trace Chromium responsible for colour.
Origin
- RussiaUrals, historic
- BrazilHematita
- Sri Lanka
- India
- Tanzania
- Madagascar
Filled dots are primary sources
Rarity
Strong colour change over one carat is among the rarest of all gems; the Ural mines were worked out in the 19th century.
- 1 Abundant
- 2 Common
- 3 Uncommon
- 4 Rare
- 5 Exceptional
Hardness
Alexandrite sits at 8.5 on the Mohs scale. It will scratch glass and holds a polish in daily wear.
Energy
Associations from crystal-healing tradition, recorded here as folklore. They are not medical claims.
Chakras
- Crown
- Heart
Element
- Air
Zodiac
- Gemini
- Scorpio
Planets
- Mercury
Properties
- Transformation
- Balance
- Joy
- Intuition
Lore
Found in the Urals in 1830, reputedly on the future Tsar Alexander II's birthday, and showing red and green, the colours of Imperial Russia. It became the army's talisman.
Its practice associations are all about duality: night and day, two natures in one body.
- Effect'Emerald by day, ruby by night.'
- SyntheticFlux-grown alexandrite is common and hard to tell from natural without a lab.