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Alexandrite

There is no such magic stone as alexandrite – in daylight it has the beauty of emerald, in the night turns into a ruby.

alexandrite gem

Although some samples of tanzanite, sapphire, quartz, spinel, garnet, fluorite and other stones show some colour change under daylight and indoor light alexandrite is the only gemstone exhibiting this rarely observed standard feature.

The stone was firstly discovered relatively soon – in 1834 in mountain Ural in Russia. This happened on the day of maturity of the future Tsar Alexander II and that’s where the stone got its name. Since it shows both red and green, the principal colors of old Imperial Russia, it inevitably became the national stone of tsarist Russia. And alexandrite jewelry became very popular among Russian monarchists after assassination of Alexander II in 1881.

For a long time it was considered a purely Russian mineral. Later deposits were found in Brazil, Zambia, Zimbabwe, India, Madagaskar, USA, Tanzania and Sri Lanka.
Russia remains the main source of the mineral for many years after the stone from the mines of the Urals became available on the market. When the Russian deposits have been exhausted the interest in the stone diminished, especially because the minerals from other Russian mines hardly ever displayed the coveted color change. This situation changes dramatically when more reserves have been discovered in Brazil. So the reputation of this amazing stone in the market received a new impetus.

alexandrite colours

Alexandrite is the most popular variety of chrysoberyl. If chrysoberyl composition would correspond on its exact chemical formula, it would be colorless. The mineral is distinguished from other chrysoberyl varieties not only by containing iron and titanium, but also due to inclusion of chromium in the molecule as a major. This is the crucial element for the spectacular color change. Like many other gemstones, alexandrite emerged millions of years ago in a metamorphic environment and required specific geological conditions. The chemical elements beryllium (a major constituent in chrysoberyl) and chromium (the coloring agent in alexandrite) have contrasting chemical characteristics and do not usually appear together and in rock types. It is unique that for the formation of this stone nature has brought these types into rocks together. Last but not least is necessary the absence of the element silica (the second most abundant element in the Earth's crust). Its absence prevents the growth of the crystal as emerald. This geological scenario has occurred only rarely in the history of the earth. As a result, alexandrite crystals are very scarce.

Daylight colour

alexandrite day colour

Indoor colour

alexandrite indoor colour

Daylight colour

alexnadrite daylight colour

Indoor colour

alexandrite indoor colour

Benign alexandrite should show intense blue-green color in daylight and purple-red at indoor light, free of unwanted shades of brown and gray. The more dramatic is the change from green to red without going through the change of brown in color, the more rare is the gemstone. Other characteristics affecting price are intensity of the colors, the purity of the stone and the cut. If the origin of the stone is known beyond dispute to be Russia we talk about a real rarity of enormous value. Nowadays alexandrite is much appreciated, second only to diamond, ruby, emerald and sapphire.

The only stone, which apparently can be confused with alexandrite is the green andalusite. However, such a substitution does not make sense, because andalusite does not occur in nature much often. As imitations are used artificial corundum and spinel.

alexandrite twocolour ring

Due to its high price there were many attempts of synthetic production of the stone. The sale of products with synthetic alexandrite with the spectacular color change from purple-blue to pink begins about 1973. But because the grow of the artificial stone is incredibly expensive and difficult its cost of not much less than the cost of natural alexandrite.

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