Often described by gem aficionados as “emerald by day, ruby by night”, alexandrite is the very rare colour-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.
Birthstones & Anniversaries
Alexandrite is a birthstone for June, along with pearl and moonstone. Alexandrite is also the gem for the 55th wedding anniversary.
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.
This absorption band allows alexandrite to shift from red to green when viewed under different light sources.
Bluish green in daylight, purplish red in incandescent light
1.746 to 1.755
0.008 to 0.010
- Mohs Hardness: 8.5
There are a number of processes used to alter the colour or apparent clarity, or to improve the durability of gems.Learn More
Some gemstones have synthetic counterparts that have essentially the same chemical, physical and optical properties, but are grown by man in a laboratory.Learn More
Any gem can be imitated – sometimes by man-made materials or by natural materials chosen by man to impersonate a particular gem.Learn More
Why We Love This Gemstone
Making alexandrite change colour from green to red is the world’s most fun use of a penlight.
This gem provides dramatic proof of how much the light source affects colour in gems.
Alexandrite can show both colour change and a cat’s-eye: two phenomena in one gem.
Fine alexandrite is green to bluish green in daylight and red to purplish red in incandescent light.
Good quality alexandrite has few inclusions. Rarely, needle-like inclusions create a cat’s-eye.
Alexandrite is most often available in mixed cuts. Its rarity means it is often cut to save weight.
Most cut gems weigh less than one carat. Larger, higher-quality gems rise in price dramatically.
Alexandrite Quality Factors: The Comprehensive Guide
Explore sources, gemmological research and the role of gems in history.
Cat’s-Eye Alexandrite with Unique Inclusion PatternMakoto Miura and Yusuke Katsurada , Jan 26, 2018 Read more in English
Titanium-bearing synthetic alexandrite and chrysoberylJennifer Stone-Sundberg , Jan 31, 2014 Read more in English
Challenges in Orienting Alexandrite: The Usambara and Other Optical Effects in Synthetic HOC-Grown Russian AlexandriteJennifer Stone-Sundberg , Apr 30, 2014 Read more in English