Some people may have never heard of Alexandrite,
some may even have a piece in jewelry in their own collection if they are lucky.
Alexandrite is ranked alongside Tanzanite and Benitoite as one of the most rare of all gemstones in the entire world. Size always affects alexandrite value. In sizes up to one carat, top-quality natural gems can sell for up to $15,000 per carat. Over one carat, the prices range from $50,000 to $70,000 per carat! That is one expensive gem! Alexandrite is rarely found in large sizes. Any specimens weighing over three carats are considered to be extremely rare. The largest cut alexandrite gemstone weighs 66 carats and is currently located in Washington, D.C.'s Smithsonian Institution. Alexandrites are often faceted in traditional shapes such as oval, round, pear, marquise and cushion cuts, but they are also commonly found in fancy shapes such as heart and trillions cuts too. They are not typically cut en cabochon, unless they possess chatoyant properties. However,the truly interesting information about Alexandrite is how it was found and sky rocketed to rare gemstone fame.
Alexander is quite stunning but more specifically, it is an extremely rare color change variety of chrysoberyl (a cyclosilicate). Despite its name, chrysoberyl, which is an aluminate of beryllium, does not actually belong to the beryl mineral group, but rather, it is classified as its own independent mineral group.
The color change phenomenon seen in alexandrite is referred to as the 'alexandrite effect'. The change in color can be observed under certain lighting conditions, typically under daylight and incandescent lighting. Alexandrite is also a strongly pleochroic gem. It can display emerald green, red, orange and yellow colors depending on which angle the stone is viewed from.
The pleochroic properties of alexandrite are completely independent from its unique color change ability. Typically, alexandrite exhibits an emerald-green color in daylight, and raspberry-red under incandescent lighting. Alexandrite can also occur with yellowish and pink colors, and extremely rare specimens can exhibit chatoyancy (cat's eye) effects when cut en cabochon. The color change 'alexandrite effect' is a result of the strong absorption of light in the yellow and blue portions of the color spectrum.
Now that you have a idea of the gemstone itself,lets dive into the history!
The history of alexandrite is quite controversial, dating back to the times of Imperial Russia. It is said that the stone was named after the Russian tsar, Alexander II (1818 - 1881), but was discovered by a French mineralist called Nils Gustaf Nordenskiöld (1792 - 1866). When Nordenskiöld first discovered alexandrite in 1834, it was initially thought to be an emerald because it was discovered in emerald mines located in Russia's Ural region, near the Tokovaya River. The specimen was later identified as a chromium bearing, color change variety of chrysoberyl. Legends claim that the discovery of alexandrite was made on the very day the future tsar of Russia became of age. Inevitably, the red and green color change stone was to be declared the official gemstone of Imperial Russia's Tsardom.
The original source for alexandrite was in the Ural region of Russia, but these mines have long been depleted. For quite some time, the worked out mines of the Urals were thought to have been the only source for large alexandrite stones, specifically specimens weighing 5 carats or more, but very recently in 1987, large specimens were discovered in Minas Gerais, Brazil. Other sources for alexandrite include Myanmar (Burma), Sri Lanka, Tanzania, India (Andhra Pradesh) and Madagascar.
When it comes to identifying Alexandrite,there are few things to take into account. Most chrysoberyl is colored by iron, but alexandrite color is a result of chromium traces. Through spectroscopic analysis and testing, alexandrite can be distinguished from other similar stones. Ordinary specimens of chrysoberyl may also contain chromium coloring agents, but unless they exhibit a color change ability, they are only identified as chrysoberyl and not Alexandrite.
Alexandrite gemstones are typically untreated, but imitation stones do exist. Occasionally, alexandrite stones may be dyed or oiled, but this is not very common. Many alexandrites are synthetic (lab-grown) and others may be natural 'simulated' gemstones, such as color change garnet, sapphire or spinel. Many lab-grown (synthetic) alexandrite stones are actually corundum (ruby / sapphire) that has been laced or infused with either chromium or vanadium to provide color. It is very expensive to create synthetic alexandrite, so even lab-grown stones can be very costly. Synthetic alexandrite has been available on the market since the 1960s.
It is truly a fascinating gem,history and all,but getting your hands on Alexanderite is very difficult in this modern age. So even if you never see or own one in your lifetime,you can admire it's beauty through photos,museums and in spirit.