Alexandrite is a rare and valuable gemstone that is prized for its unique color-changing properties. It is a variety of chrysoberyl, which is a mineral composed of beryllium, aluminum, and oxygen. Alexandrite was first discovered in the Ural Mountains of Russia in the 1830s, and it quickly gained popularity among the Russian aristocracy.
The discovery of alexandrite is credited to the Finnish mineralogist Nils Gustaf Nordenskiöld, who found the gemstone in 1830 while prospecting in the Ural Mountains. It was named after Alexander II, who was the future Czar of Russia at the time. Nordenskiöld initially thought the gemstone was emerald, but he soon realized that it had a unique color-changing property that set it apart from any other gemstone known at the time.
One of the most remarkable properties of alexandrite is its color-changing ability. The gemstone appears green in natural light but changes to a reddish-purple color in artificial light. This is due to the presence of chromium in the crystal lattice structure, which causes the absorption of certain wavelengths of light. The color change is most pronounced in high-quality specimens and can be seen even in low light conditions.
In addition to its color-changing properties, alexandrite is also known for its high degree of birefringence. Birefringence is the property of a material to split a single beam of light into two beams, each of which travels at a different speed. This property is what gives alexandrite its unique internal reflections and luster.
Despite its stunning properties, alexandrite is more rare than diamond. In fact, it is one of the rarest gemstones in the world. This is because it is found in only a few locations around the world, and the gemstones that are found are typically small and of low quality. The finest specimens of alexandrite are found in the Ural Mountains of Russia, but other sources include Sri Lanka, Brazil, and East Africa.
In terms of its physical properties, alexandrite has a hardness of 8.5 on the Mohs scale, which makes it a durable gemstone that can withstand wear and tear. It has a specific gravity of 3.7-3.8, which is higher than most other gemstones. This means that it is denser than other gemstones of the same size, which gives it a greater feeling of substance and weight.
In conclusion, alexandrite is a gemstone that is prized for its unique color-changing properties, high degree of birefringence, and rarity. It was first discovered in the Ural Mountains of Russia in the 1830s and quickly gained popularity among the Russian aristocracy. Today, it remains a highly sought-after gemstone among collectors and jewelry enthusiasts. If you are lucky enough to come across an alexandrite, it is sure to be a treasured addition to any collection.