Alexandrite – Colour-Changing Chrysoberyl (Set of 10)
Appearance & Properties
Alexandrite is the colour-changing variety of chrysoberyl, a beryllium aluminium oxide with the formula BeAl₂O₄. In daylight it commonly appears green, bluish green or sometimes olive green; under incandescent or warm LED light it may shift toward red, purplish red or raspberry tones. This effect, called the alexandrite effect, is caused mainly by chromium absorbing selected parts of the visible spectrum. The change is not simply pleochroism, although alexandrite can also show strong directional colour. Fine material is transparent to translucent, while inclusions are common. Chrysoberyl reaches 8.5 on the Mohs scale and has good everyday durability, though sharp blows and sudden temperature changes should still be avoided. Some specimens show chatoyancy, producing an alexandrite cat’s-eye.
History & Discovery
Alexandrite is generally associated with the Russian Urals and is usually dated to the early 1830s, or about 1830. Early accounts connect its recognition with the emerald-mining region near the Tokovaya River, although the precise details of the first discovery and naming are not certain. The gem is traditionally said to have been named for Grand Duke Alexander Nikolaevich, the future Tsar Alexander II. Russian alexandrite soon became associated with the imperial court and was prized for its unusual appearance. The original Ural deposits later declined substantially, while discoveries in other countries broadened the supply. Today, the name alexandrite is properly used for natural colour-changing chrysoberyl; laboratory-created material may reproduce the phenomenon but should be identified separately.
Occurrences
The historic source is the Urals of Russia, especially the area around Tokovaya. Important later deposits have been found in Brazil, notably Minas Gerais, as well as in Sri Lanka, Tanzania, Madagascar and Zimbabwe. Indian material has also entered the market. These localities can produce stones with different background colours, clarity and strength of colour change. Brazilian alexandrite is particularly noted for attractive changes in some stones, while Sri Lankan material is often larger but may show less dramatic colour contrast. Fine natural alexandrite remains uncommon because strongly coloured, transparent crystals are difficult to find. A locality list describes known geological sources only; it does not establish the origin of any individual gemstone.
Famous Examples & Interesting Facts
Large, transparent alexandrites are unusual because most rough crystals are small, included or unevenly coloured. The Smithsonian National Gem Collection is known to include a 65.7-carat faceted alexandrite, often cited among the notable large examples in a museum collection. One of the gem’s most fascinating features is that its colour change depends on the light source and on the observer’s surroundings: a stone may look greener in daylight and redder in warm artificial light. Alexandrite is not a separate mineral species but a variety of chrysoberyl. It should also not be confused with colour-change sapphire, colour-change garnet or glass, which can show a similar visual effect but have different compositions.
Jewellery & Use
Alexandrite is commonly fashioned as an oval, cushion, round or mixed cut, with the proportions chosen to display both body colour and colour change. Transparent stones are suited to rings, pendants, earrings and other jewellery, while chatoyant material is usually polished as a cabochon. Its 8.5 Mohs hardness and generally good toughness make it suitable for regular wear, although a protective setting is sensible for a ring worn daily. Clean it with lukewarm water, mild soap and a soft brush, then rinse and dry carefully. Avoid harsh chemicals, sudden thermal shock and careless blows. Natural, laboratory-created and imitation materials exist; treatments and identification vary, so product-specific claims require reliable documentation.
Symbolism, Astrology & Tradition
Alexandrite is widely used as a modern June birthstone, alongside pearl and moonstone, although birthstone lists vary by organisation and region. Its Russian history has encouraged symbolism connected with imperial colour, transformation and the meeting of opposites: green in daylight and red in warm light. Some modern crystal and esoteric traditions associate it with adaptability, balance or personal change. These are beliefs and symbolic interpretations, not scientific findings, and alexandrite has no medically established healing effect. Zodiac links are inconsistent; Gemini, Scorpio and other signs are mentioned in different modern sources, but there is no universally accepted astrological assignment.