Alexandrite
Alexandrite — A Gemstone That Changes Colour with the Light
Alexandrite is the colour-change variety of chrysoberyl. Although the name resembles beryl, chrysoberyl is a different mineral with a different composition and structure.
Its defining feature is a shift from green to bluish green in daylight to red, purplish red and sometimes brownish red in incandescent light. The strength of the change and exact colours vary from stone to stone.
Origin of the Name
Alexandrite was named in 1834 in honour of Alexander II, who was then heir to the Russian throne and later became Tsar of Russia. The name reflects the gemstone’s historical connection with Russia, where it was first discovered in the Ural Mountains.
Gemological Properties
| Mineral | Chrysoberyl |
|---|---|
| Variety | Alexandrite |
| Chemical composition | Beryllium aluminium oxide — BeAl₂O₄ |
| Mohs hardness | 8.5 |
| Refractive index | 1.746–1.755 |
| Birefringence | 0.008–0.010 |
| Specific gravity | Approximately 3.73 |
| Main optical phenomenon | Colour change according to the light source |
How Does the Colour Change Occur?
The colour change results from the way the stone absorbs and transmits light, combined with differences between light sources. As the composition of the light changes, the colour we see can also change.
Colour change caused by switching the light source should be distinguished from pleochroism — different colours seen when viewing a crystal from different directions. Alexandrite can display both phenomena, but they are not the same.
Colour, Cut and Quality
Assessment considers the beauty of the colour under both types of lighting, the degree of change between them, clarity and cut. A pronounced change is not the only consideration: the stone should also show attractive colour and a lively appearance under each light source.
A suitable cut takes crystal orientation and colour presentation into account. Very dark stones may appear almost black, while very light stones may show weak colour.
Rarity and Price
Russian-origin alexandrite generally commands a price premium over material from many other sources when comparing stones of similar quality. Origin alone does not determine value: colour, colour change, clarity, cut and weight remain important.
High-quality natural alexandrite is very rare and expensive. Price depends on the beauty of its colours under both light sources, the strength of its colour change, clarity, cut and weight. Large stones combining attractive colours with a distinct colour change are especially rare, so their price per carat can increase substantially as weight increases.
Natural alexandrite of the highest quality can command tens of thousands of US dollars per carat, particularly stones with impressive colours and a pronounced colour change.
Natural Alexandrite, Synthetics and Imitations
Laboratory-grown synthetic alexandrite also exists. Other colour-changing materials can be used as imitations.
Colour change alone is insufficient to identify alexandrite or establish that it is natural. When buying a stone of significant value, a report from a recognised gemological laboratory can help confirm its identity and whether it is natural or synthetic.
Setting, Care and Cleaning
Alexandrite is a durable gemstone suitable for rings and daily wear. However, the suitability of a setting depends on the individual stone and any fractures or inclusions.
Clean with lukewarm water and a little mild soap, rinse and dry with a soft cloth. Before steam or ultrasonic cleaning, confirm that the stone's condition and treatments allow it. Fracture-filled stones should only be cleaned with soap and water.
Sources Around the World
Alexandrite is known from Russia's Ural Mountains and other sources including Brazil, Sri Lanka and Tanzania. Colour-change quality varies between stones from every source.
Spiritual and Symbolic Meaning — Beliefs and Traditions
Alexandrite is associated with happiness, inner reflection and change. It symbolises the possibility of transforming the experiences and energies we encounter into sources of harmony and growth.
In a spiritual context, it is associated with higher dimensions of awareness and discovering the self beyond everyday life. It invites us to cultivate happiness through choice and inner commitment, and to see ourselves as active participants in creating and sharing it.
These meanings belong to the realm of belief and symbolism. They can give jewellery personal significance, but they are not proven gemological properties or a promise of healing, protection or a change in health.