Alexandrite: meaning, colour-change effect and how to choose

What is alexandrite?

Alexandrite is a variety of chrysoberyl, a beryllium aluminium oxide (BeAl2O4) containing traces of chromium. Note that, despite its name, chrysoberyl is not beryl: it is a different mineral. Its hardness is 8.5, just below that of corundum (ruby, sapphire): it is one of the hardest natural stones.

Its distinctive feature is its alexandrite effect, a colour change. In daylight or under a fluorescent tube, the stone looks green to blue-green. Under the red light of an incandescent bulb or a candle, it becomes brownish red to purplish red. It is sometimes summed up as “emerald by day, ruby by night”. The phenomenon comes from the way the crystal absorbs light. It should not be confused with pleochroism, which is a change depending on the viewing angle (alexandrite also has this property).

The historic deposits are in Russia, in the Urals, now exhausted for the finest stones. There are also deposits in Brazil, Sri Lanka, India, Madagascar and Tanzania, with stones that are sometimes less clear.

History and legend

The story most often told places the discovery in the Urals in the 1830s: the stone is said to have first been taken for an emerald, then named in honour of the future Tsar Alexander II, whose military colours, green and red, it is said to have borne. The dedication is dated 17 April 1834, and the stone is attributed to the Finnish mineralogist Nils Gustaf Nordenskiöld, who described it in 1842.

But the sources differ. Some mining historians now credit the discovery to Yakov Kokovin, and place the opening of the emerald mine as early as 1831. The romantic details (the exact day, taking it for an emerald) are partly legend: we give them as such.

Traditional symbolism

A stone that changes colour with the light has naturally inspired the idea of adaptation, duality and transformation: two faces in a single stone. In the modern tradition of stones, it is associated with inner balance, confidence and creativity. There is no ancient tradition, since the stone has been known only since the 19th century.

These associations are symbolic and have no scientific evidence behind them. They matter only if they speak to you.

Traditional correspondences

How to use it

• In jewellery: rings and pendants, in faceted stone or cabochon. Its great hardness suits everyday jewellery. See the guide to gemstone jewellery.
• As a collector's stone: a small natural stone, with a certificate, is above all a collector's object.
• For observation: watching the stone move from one light to another is the best “exercise”: compare daylight with a light bulb.

Being rare and expensive, genuine alexandrite is above all a jewellery purchase, best made with a certificate.

Care and cleansing

• Water: warm soapy water and a soft brush are enough; the stone is stable.
• Sunlight and heat: the colour is stable under light. Avoid, however, sudden thermal shocks.
• Ultrasonic cleaners: reserved for stones without fissures; ask a jeweller for advice.
• Knocks: despite its hardness of 8.5, a sharp blow can chip it.

See also the guide to cleansing and recharging your stones.

Recognising a real alexandrite and avoiding imitations

This is where you need to be most careful: natural alexandrite is rare, and imitations are numerous.

• Synthetic alexandrite: made in a laboratory, it has the same composition and the same effect. It is not an imitation, but it is worth much less. It must be sold as “synthetic” or “lab-created”.
• Synthetic colour-change corundum: sometimes sold as “alexandrite”. It shifts from blue-violet to mauve, without passing through a true green.
• Colour-change spinel: same remark.
• A very low price for a stone of several carats is the first warning sign.

For a natural stone, ask for a certificate from a gemmological laboratory: it is the only safe way. See also the guide to choosing your stones.

How to choose

• The intensity of the change is the main criterion: the more clearly the colour moves from green to red, the more the stone is sought after.
• Size: beyond one or two carats, prices rise very quickly.
• The certificate and the exact name (natural or synthetic) are essential.
• More accessible alternatives: for a play of colours, look at labradorite or moonstone, also a June birthstone.

Frequently asked questions

Also read

The meanings mentioned belong to tradition and symbolism. They are neither promises of results nor medical advice. Back to Guide to stones.