The world of gemstones is filled with marvels, but few possess the captivating duality of alexandrite. As one of the modern birthstones for June, this remarkable gem is celebrated for its extraordinary ability to change color, shifting from a verdant green in daylight to a rich, purplish-red under incandescent light. This phenomenon, often described as "emerald by day, ruby by night," makes alexandrite a subject of fascination for collectors, jewelers, and gemologists alike. Its discovery is steeped in imperial Russian history, and its unique optical properties are a direct result of its specific geological formation. This article will explore the rich history, distinctive gemological characteristics, and enduring symbolism of alexandrite, the enigmatic birthstone of June.
History and Lore: A Gem Fit for a Czar
Alexandrite’s story begins not in the mists of ancient legend, but in the heart of the 19th-century Russian Empire. The gem was first discovered in the Ural Mountains of Russia in the early 1830s. The circumstances of its discovery were as fortuitous as the gem itself. As the story goes, mineralogists prospecting in the region initially mistook the green stones for emeralds. However, the gem’s true identity was revealed when a sample was observed in the evening lamplight, where it transformed to a reddish hue, a color highly favored by the Russian military and a symbol of the empire.
The gem was named in honor of the future Tsar Alexander II, whose birthday was on the same day the stone was found. This connection to the Russian monarchy immediately elevated its status. For a time, alexandrite became a symbol of national pride and was highly prized by the Russian aristocracy. Its dual coloration was seen as a reflection of the nation's vast landscape—the green of its forests and the red of its military colors. The gem’s popularity, however, was largely confined to Russia until the early 20th century. Following the Russian Revolution, the mines in the Ural Mountains became less productive, and the gem’s prevalence waned. It was not until new deposits were discovered in Ceyron (now Sri Lanka) and later in Brazil that alexandrite once again gained international recognition as a rare and desirable gemstone.
Geological Formation and Sources
Alexandrite is the color-changing variety of the mineral chrysoberyl. Its chemical formula is BeAl₂O₄. The gem’s formation requires a unique set of geological conditions. Chrysoberyl is typically found in mica schists and other metamorphic rocks, formed under high temperatures and pressures. The critical element that gives alexandrite its signature color change is the presence of chromium as a trace impurity within the crystal lattice. Interestingly, chromium also gives emerald its green color and ruby its red. In alexandrite, the specific concentration and interaction of chromium with the gem's inherent chemistry under different light sources create the dramatic color shift.
The primary historical source for alexandrite remains the Ural Mountains of Russia. These deposits, particularly those in the Yekaterinburg region, produced the finest material known for its intense color change from a vivid green to a deep red. However, as noted, these mines are no longer a major source of commercial-quality alexandrite.
Modern sources for alexandrite are more widespread. Sri Lanka has emerged as a significant producer, yielding alexandrite that often displays a more subtle color change, shifting from greenish-gray to a brownish or purplish-red. Brazilian deposits, particularly in the state of Minas Gerais, are also known to produce alexandrite. The material from Brazil can vary in quality, but some specimens exhibit a strong color change comparable to the historic Russian gems. Other, less significant sources have been reported in Madagascar, Myanmar, and India, but these do not currently contribute large quantities of gem-quality alexandrite to the market.
The rarity of fine alexandrite cannot be overstated. The specific conditions required for its formation, combined with the limited number of locations that produce gem-grade material, make large, clean stones with a strong color change exceptionally rare and valuable.
Gemological Properties
Alexandrite possesses a unique combination of physical and optical properties that define its character and value. Understanding these characteristics is essential for identifying the gem and appreciating its rarity.
The Phenomenon of Color Change
The defining characteristic of alexandrite is its pleochroism, specifically a strong form of color change. This is not a trick of the light but a result of how the gem absorbs light. The chromium ions in the crystal structure absorb light in the yellow portion of the spectrum. In daylight, which is rich in blue and green wavelengths, the gem transmits these colors, appearing green. In incandescent or lamp light, which is rich in red and yellow wavelengths, the gem transmits the red light, appearing red or purplish-red. The quality of a color change is graded on a scale from "weak" to "strong" or "distinct," with the most valuable stones showing a dramatic shift from a pure, saturated green to a pure, saturated red.
Key Physical Characteristics
Beyond its color change, alexandrite has a set of durable physical properties that make it suitable for all types of jewelry, particularly rings.
| Property | Value / Description |
|---|---|
| Mineral | Chrysoberyl |
| Chemical Formula | BeAl₂O₄ |
| Hardness (Mohs Scale) | 8.5 |
| Crystal System | Orthorhombic |
| Refractive Index | 1.746 – 1.755 |
| Specific Gravity | 3.73 – 3.75 |
| Luster | Vitreous (glass-like) |
Hardness: With a hardness of 8.5 on the Mohs scale, alexandrite is an exceptionally hard and durable gemstone. This makes it highly resistant to scratching and suitable for everyday wear in rings and other jewelry. It is harder than most other popular gemstones, including topaz, spinel, and sapphire.
Clarity: Like many gemstones, alexandrite can contain inclusions. Natural alexandrite often has "fingerprints" or "feather" inclusions. Some characteristic inclusions, such as long, parallel tubes or "trapiche" patterns (a six-rayed star pattern), can help gemologists identify the stone. While clean stones are more valuable, the presence of inclusions can also serve as evidence of the gem's natural origin.
Cut and Carat: Due to its rarity, alexandrite is often cut to retain as much weight as possible. Common cuts include oval, pear, and round shapes. The cut is crucial for displaying the color change to its best effect; a well-proportioned stone will show a more dramatic shift. Large alexandrites are exceptionally rare, and the price per carat increases exponentially with size.
Symbolism and Metaphysical Beliefs
Alexandrite's dramatic color change has imbued it with rich symbolism and a host of metaphysical beliefs throughout its history. Its dual nature is seen as a representation of the balance between the physical and spiritual worlds.
In Russian culture, the gem’s ability to shift from the green of the forest to the red of the military was seen as a symbol of the nation's strength and natural beauty. On a more personal level, alexandrite is often associated with duality and balance. It is believed to harmonize the intellect and the emotions, helping the wearer to see both sides of an issue and to embrace change.
In metaphysical traditions, alexandrite is considered a stone of good omens. It is said to bring luck, fortune, and intuition to its wearer. Some beliefs hold that the gem can intensify feelings of love and passion, while also providing a sense of calm and clarity. It is also associated with the crown chakra, believed to enhance spiritual awareness and connection to higher consciousness.
As a birthstone for June, alongside pearl and moonstone, alexandrite offers a modern and powerful option. It is often gifted to celebrate the 55th wedding anniversary, a testament to its enduring appeal and rarity.
Care and Cleaning
Despite its hardness, proper care is essential to maintain the beauty of an alexandrite gemstone. Fortunately, its durability makes it relatively easy to care for.
Cleaning: The safest way to clean alexandrite jewelry is with warm water, a mild soap (like dish soap), and a soft brush. Gently scrub the gemstone and the setting to remove any dirt or oils. Rinse thoroughly with clean water and dry with a soft, lint-free cloth. Avoid using harsh chemicals, bleach, or strong detergents, as these can damage the stone or its setting. Ultrasonic and steam cleaners are generally safe for alexandrite, but it is always wise to check with a professional jeweler first, especially if the stone has significant inclusions or if the jewelry setting is delicate.
Storage: When not being worn, store alexandrite jewelry separately from other gemstones to prevent scratching. A soft pouch or a compartmentalized jewelry box is ideal. While alexandrite is durable, it is still harder than many other gems and can scratch them. Avoid exposing the gemstone to extreme temperature changes, as this could potentially cause damage, although this is rare due to the gem's stability.
Conclusion
Alexandrite stands as a testament to the wonders of the natural world. Its discovery in the Russian Ural Mountains, its imperial heritage, and its mesmerizing color-changing ability combine to create a gemstone of unparalleled intrigue. As the primary modern birthstone for June, it offers a unique and meaningful choice for those born in this month, symbolizing joy, intuition, and the ability to adapt to life's changes. From its rare geological origins to its enduring legacy in both fine jewelry and metaphysical lore, alexandrite continues to captivate and inspire. Its exceptional hardness ensures it will remain a cherished heirloom for generations, its colors shifting from green to red as a perpetual reminder of nature's artistry and the enduring allure of a true gemological marvel.