Alexandrite, one of the birthstones for June, is a form of the mineral chrysoberyl and is one of the rarest colored gemstones.
It has a shorter history than most gemstones, and is best known for its sensational ability to change color depending on nature of ambient lighting (known as the 'alexandrite effect').
Alexandrite normally has a green or bluish-green color in daylight, but unlike other chrysoberyl stones it turns a soft shade of red, purplish-red or raspberry red in incandescent light. Other varieties can be yellowish or pink in daylight and a columbine or raspberry red by incandescent light. The reason for this unique color change effect lies in its chemical structure and the way it absorbs light, and it makes alexandrite one of the most valuable gemstones of all at its finest quality.
Like other chrysoberyl stones, including cat's eye, alexandrite is normally found in thick tabular crystals which often come in twins.
Measuring at 8.5 on the Moh's scale, alexandrite is a good, durable choice for jewelry.
Stones of five carats and larger were traditionally thought to be found only in the Ural Mountains, in Russia, but they've since also been found in Brazil, India, Sri Lanka and Madagascar. Certain labs can produce synthetic stones with the same properties as natural alexandrite.
Alexandrite was first discovered in 1830 in Russia’s Ural Mountains. It was named after the young Alexander II, heir apparent to the throne, and the stone caught people's attention not least for the fact that its red and green colors mirrored the Imperial Russian flag.
Since then, the Russian deposits were exhausted and interest in the stone decreased, especially since alexandrites from other mines hardly ever displayed the desired color change. Lab-grown alexandrites have been produced since the 1960s, but the process remains quite costly to create a true color change.
In 1987, natural alexandrites were discovered in Brazil demonstrating both a distinctive colour change and good clarity and colour. This rejuvenated the buzz around the stone, and although it's still considered rare, it's stocked by specialized gemstone dealers. Alexandrite is said to symbolize prosperity and longevity.
Natural alexandrite's rarity makes it extremely valuable, and its value increases with good clarity, strong colors and a spectacular color change.
The ideal alexandrite has a medium tone and intense or near-vivid colors. Top quality one-carat Russian gems have been said to sell for as much $10,000, and fine alexandrites weighing more than five carats can retail for as much as $40,000 per ct.
Alexandrite gemstones are normally untreated, but occasionally stones may be dyed or oiled.
Alexandrite is one of the world's most exotic gemstones for its rarity and its unique color-changing phenomenon.
It's an attention-grabbing stone for obvious reasons, and the fact it's so durable makes it even more desirable for use in jewelry. While larger natural alexandrites are still difficult to come by, lab-grown stones are popular choices for giving jewelry an intriguing and spectacular appearance.