ALEXANDRITE GEMSTONE

Alexandrite is part of the family of gemstones known as Chrysoberyl.
It is an extremely rare and very expensive gemstone most noted for its color changing abilities. It is the third hardest natural rock on earth.
This rock is especially interesting, and expensive due to its color changing properties. Shades are greenish in natural light, and reddish to violet under artificial light.

HISTORY
Alexandrite, the color change gem, was discovered by the Finnish mineralogist Nils Gustaf Nordenskiold on the Russian Tsarevitch Alexander's 16th birthday on April 17, 1834 and named alexandrite in honor of the future Tsar Alexander II of Russia.
Because of the green and red hues inside the gemstone, alexandrite became the national stone.

COLOR CHANGING PROPERTIES

Alexandrite is also one of the few gems that can actually change colors depending on the time of day and amount of light hitting the gem.

Alexandrite often appears to be a rich green or bluish-green color when sunlight reflects off the stone. That same gemstone reflects red hues at night when seen under incandescent light (light bulbs or candles) turning from a light shade of red to a deep purplish-red. The color change is caused by aluminum impurities in the stone being displaced by chromium oxide.
This color shift is independent of any change of hue with viewing direction through the crystal that would arise from Pleochroism.
Alexandrite is not the only gemstone that can change colors, tourmalines and opals can appear to be different colors based on the different elements within the stones.
Stones that display a change of 30% or less are of marginal interest and are arguably not even alexandrite.

CHARACTERISTICS

SOURCES
Today, Russia is still the primary source for alexandrite, 5 carats and larger were traditionally thought to be found only in the Ural Mountains. Other deposits are located in Brazil, Tanzania, Burma, Madagascar, and Zimbabwe. In the past decade, alexandrite has also been found in India (Andhra Pradesh).
Recently, excellent quality stones have been found in Sri Lanka, India, and the Tanduru region of Tanzania with all the color and life of an ideal Russian Alexandrite.
Alexandrite in sizes over 3 carats are very rare.

CLARITY
In terms of clarity, alexandrite is comparable to ruby, with clean faceted stones in sizes above one carat being rare and extremely rare in sizes above 2–3 carats. Negative crystals and parallel rutile silk are common inclusions.

CUT
In the market, Alexandrites are found in a variety of shapes and cutting styles. Ovals are cushions are the most common, but rounds are also seen, as are other shapes, such as the emerald cut.

VALUE
Alexandrite is one of the world‘s most expensive gems, with prices similar to those fetched by fine ruby or emerald. However, like all gem materials, low-quality pieces may be available for a few dollars per carat. Such stones are generally not clean enough to facet.
Significant brown or gray components in either of the twin colors will lower value dramatically.

 
HARDNESS
It’s a hard, durable stone rated at 8.5 on the Mohs Scale. The specific gravity of alexandrite is between 3.64 and 3.74. The specific gravity weighs the density of a stone in comparison to the volume of water displaced.

POWERS
Alexandrite was also thought to give mystical powers, the possibility of predicting the future and providing the wearer with good health and luck.