Alexandrite

History and lore

Alexandrite is a young gem with no ancient history. It was found in the 1830s in the emerald mines near the Tokovaya River in the Ural Mountains, and was named in honour of the heir to the Russian throne, the future Alexander II. A well-known story says the stone was presented on the day he came of age in 1834; the tale is attractive but its details are not securely documented. The Finnish mineralogist Nils Gustaf Nordenskiöld, who studied the new mineral, is usually credited with describing and naming it.

The stone's remarkable property is a change of colour: bluish green in daylight, purplish red under candlelight or incandescent lamps. Its two colours echoed the green and red of imperial Russian military uniforms, and it became fashionable in Russia in the nineteenth century. In America the gem expert George Frederick Kunz, who worked for Tiffany & Co., admired it greatly, and Tiffany set Russian alexandrites in jewellery around 1900. The Ural deposits were soon largely worked out, and fine stones became rare until new finds in Sri Lanka, East Africa, India and, from 1987, at Hematita in Brazil.

In the traditions

Because it was discovered so recently, alexandrite does not appear in the High Priest's breastplate, the Revelation foundations, the medieval lapidaries, Agrippa or the Navaratna, and no traditional planet is assigned to it. Some modern Western writers link it with Mercury or with Gemini because of its double nature, and some Vedic astrologers treat it as an alternative to emerald for Mercury; these are recent associations.

Its relative, cat's-eye chrysoberyl, does have deep roots in Indian tradition as lehsunia or vaidurya, the Navaratna stone of the shadow planet Ketu (see cat's eye). Rare stones combine both effects as cat's-eye alexandrite.

Meaning and symbolism

Alexandrite joined pearl and moonstone as a June birthstone in the American list revised in 1952 (see June). Its symbolism grows from the colour change: balance between opposites, adaptability, joy and good omen, and, in Russia, loyalty to the crown. These are cultural meanings of the nineteenth and twentieth centuries; no evidence shows that the stone affects health or fortune.

The mineral

Alexandrite is a variety of chrysoberyl, a beryllium aluminium oxide. Traces of chromium absorb light in a narrow band between the green and red ends of the spectrum, so the stone's apparent colour depends on whether the light source is richer in blue-green (daylight) or in red (flame and incandescent light). Fine stones show a strong, clear change; many show only a partial one. Chrysoberyl is hard (8.5) and tough, making alexandrite a durable ring stone.

Because natural alexandrite is costly, imitations are common. Synthetic alexandrite has been grown since the 1970s by flux and pulling methods and is chemically real alexandrite. Much "alexandrite" sold to tourists is synthetic colour-change corundum or spinel, which shows a shift from greyish blue to purple rather than green to red. A laboratory report is the only safe proof. Clean with warm soapy water.

Sources and further reading

• The Curious Lore of Precious Stones — George Frederick Kunz, 1913
• Russian Alexandrites — Karl Schmetzer, 2010
• Gems: Their Sources, Descriptions and Identification — Robert Webster, 1962 (6th ed., ed. Michael O'Donoghue, 2006)
• Gemstones of the World — Walter Schumann, 1977 (later editions)