Daily Archives: July 28, 2010
While browsing over my supplier’s website last month, I chanced upon a stone she described as “color changing”. It’s name was Alexandrite. The name sounded so mysterious and fascinating! Ever curious, I googled it up and this was what I found out:
This rare gemstone is named after the Russian tsar Alexander II (1818-1881), the very first crystals having been discovered in April 1834 in the emerald mines near the Tokovaya River in the Urals. The discovery was made on the day the future tsar came of age. Although alexandrite is a relatively young gemstone, it certainly has a noble history. Since it shows both red and green, the principal colours of old Imperial Russia, it inevitably became the national stone of tsarist Russia.
Beautiful alexandrite in top quality, however, is very rare indeed and hardly ever used in modern jewellery. In antique Russian jewellery you may come across it with a little luck, since Russian master jewellers loved this stone. Tiffany’s master gemmologist George Frederick Kunz (1856-1932) was also fascinated by alexandrite, and the jeweller’s firm produced some beautiful series of rings and platinum ensembles at the end of the 19th and beginning of the 20th century. Smaller alexandrites were occasionally also used in Victorian jewellery from England.
The magic of changing colours
The most sensational feature about this stone, however, is its surprising ability to change its colour. Green or bluish-green in daylight, alexandrite turns a soft shade of red, purplish-red or raspberry red in incandescent light. This unique optical characteristic makes it one of the most valuable gemstones of all, especially in fine qualities.
Alexandrite is very scarce: this is due to its chemical composition. It is basically a chrysoberyl, a mineral consisting of colourless or yellow transparent chrysoberyl, chrysoberyl cat’s eye and 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 major impurity. And it is this very element which accounts for the spectacular colour change. Rarely, vanadium may also play a part. According to CIBJO nomenclature, only chrysoberyls displaying a distinct change of colour may be termed alexandrite.
Of course, with History being one of my major (and favorite) subjects in college, I had to dig out it’s whole history:
The alexandrite variety displays a color change (alexandrite effect) dependent upon the nature of ambient lighting. This color shift is independent of any change of hue with viewing direction through the crystal that would arise from pleochroism. Both these different properties are frequently referred to as “color change”, however. Alexandrite results from small scale replacement of aluminium by chromium ions in the crystal structure, which causes intense absorption of light over a narrow range of wavelengths in the yellow region of the spectrum. Alexandrite from the Ural Mountains in Russia is green by daylight and red by incandescent light. Other varieties of alexandrite may be yellowish or pink in daylight and a columbine or raspberry red by incandescent light. The optimum or “ideal” color change would be fine emerald green to fine purplish red, but this is exceedingly rare. Because of their rarity and the color change capability, “ideal” alexandrite gems are some of the most expensive in the world.
According to a widely popular but controversial story, alexandrite was discovered by the Finnish mineralogist Nils Gustaf Nordenskiöld, (1792–1866) on the tsarevitch Alexander’s sixteenth birthday on April 17, 1834 and named alexandrite in honor of the future Tsar Alexander II of Russia. Sometimes, Nils Gustaf Nordenskiöld is confused with his son, Adolf Erik Nordenskjöld (1832–1901), also a famous Finnish geologist, mineralogist and Arctic explorer who accompanied his father to the Ural Mountains to study the iron and copper mines at Tagilsk in 1853. However, Adolf Erik Nordenskiöld was only two years old when Alexandrite was discovered and only ten years old when a description of the stone was published under the name of Alexandrite for the first time.
Although it was Nordenskiöld who discovered alexandrite, he could not possibly have discovered and named it on Alexander’s birthday. Nordenskiöld’s initial discovery occurred as a result of an examination of a newly found mineral sample he had received from Perovskii, which he identified as emerald at first. After the discovery of emeralds in the roots of an upturned tree, the first emerald mine had been opened in 1831, not long before Nordenskiöld had received this particular sample.
Confused with the high hardness however, he decided to continue his examinations. Later that evening, while looking at the specimen under candlelight, he was surprised to see that the color of the stone had changed to raspberry-red instead of green. Later, he confirmed the discovery of a new variety of chrysoberyl, and suggested the name “diaphanite” (from the Greek “di-“, twice- and “aphanès”, inapparent[dubious – discuss]).
The name of the first person to actually find this stone is unknown. However, the first person to bring it to public attention, and ensure that it would be forever associated with the Imperial family was Count Lev Alekseevich Perovskii (1792-1856.)
The finest alexandrites up to 5 carats (1,000 mg) are being found in the Ural Mountains, but the largest cut stones are in the 30 carats (6.0 g) range, though many fine examples have been discovered in Sri Lanka (up to 65 cts.), India (Andhra Pradesh), Brazil, Myanmar, and especially Zimbabwe (small stones usually under 1 carat (200 mg) but with intense color change). Overall, stones from any locale over 5 carats (1.0 g) would be considered extremely rare, especially gems with fine color change. Alexandrite is both hard and tough, making it very well suited to wear in jewelry.
The gem has given rise to the adjective “alexandritic”, meaning any transparent gem or material which shows a noted change in color between natural and incandescent light. Some other gem varieties of which alexandritic specimens have been found include sapphire, garnet, and spinel.
Some gemstones described as lab-grown (synthetic) alexandrite are actually corundum laced with trace elements (e.g., vanadium) or color-change spinel and are not actually chrysoberyl. As a result, they would be more accurately described as simulated alexandrite rather than synthetic but are often called Czochralski Alexandrite after the process that grows the crystals. (source)
With all this information in my head, I closed my eyes, took a deep breath, and purchased…….A STRAND!!!!! That’s how impulsive I can get especially when I see things which I think are one of a kind and worth it.
After 3 weeks of waiting, she finally arrived!
This is how she looks next to my other babies (agate, kyanite, quartz):
Can you find it? 🙂
This is what I woke up to this morning:
Then with a little change of lighting:
This is the time when reddish hues became visible but unfortunately I don’t think the camera caught it:
The dilemma now is designing something that will not only incorporate my signature look but make the most out of it……any suggestions, perhaps?