Alexandrite

These rare gemstones are named after the Russian tsar Alexander II (1818-1881), the very first crystals that having been discovered in April 1834 in the emerald mines near the Tokovaya River in the Urals. This discovery was made on the day of future tsar came to age. Although alexandrite is the relatively young gemstone, it certainly had a noble history. Since it shows both red and green color, the principal colors of old Imperial Russia, it inevitably became a national stone of tsarist Russia.

Beautiful alexandrite in top quality, however, is very rare indeed and also hardly ever used in modern jewellery. In antique Russian jewellery you could come across it with a little luck, from Russian master jewelers loved this stone. Tiffany’s master gemologist George did produced some beautiful series of rings and also platinum ensembles at the end of the 19th and beginning of the 20th century. Smaller alexandrite was occasionally also used in the Victorian jewellery from England.

The magic of changing colors

The most sensational feature about this Alexandrite, however, is its surprising ability to change its colour. Green and bluish-green in daylight, alexandrite turns a soft shade of red, purplish-red and raspberry red in incandescent light. This unique optical characteristic makes it one of the most valuable gemstones from all, especially in fine qualities

Alexandrite is very scarce: this is due to the chemical composition. It is basically a chrysoberyl, a mineral consisting of colorless and yellow transparent chrysoberyl, chrysoberyl cat’s eye and also colour-changing alexandrite (also in cat’s eye varieties). It differs from other chrysoberyls in that it not only contains iron and titanium, but also chromium as a part of major impurity. And it is this very element that accounts for the spectacular colour change. Rarely, vanadium may also play a part. According to CIBJO nomenclature, only chrysoberyls are displaying a distinct change of colour may be termed alexandrite.

Like many other gemstones, alexandrite was also emerged millions of years ago in a metamorphic environment. But unlike many others, its formation required specific geological conditions. The chemical elements beryllium (a major constituent in chrysoberyl) and chromium (the coloring agent in alexandrite) had contrasting chemical characteristics and did not as a rule occur together, usually being found in contrasting rock types. Not only has Nature brought these contrasting rock types into the contact with each other, but a lack of the chemical element silica (the second most common element in the Earth's crust) may also required to prevent the growth of emerald. This geological scenario has occurred only rarely in the Earth's history and, as a result, alexandrite crystals are very scarce indeed.