The gemstone world holds few marvels as captivating as alexandrite, a rare variety of chrysoberyl celebrated for its extraordinary ability to change color. Often described by connoisseurs as "emerald by day, ruby by night," this gem exhibits a distinct green to bluish green hue in natural daylight, which transforms into a rich red to purplish red under incandescent light. This dramatic optical phenomenon, combined with its scarcity, elevates alexandrite to one of the most valuable and sought-after gemstones on the market.
As one of the official birthstones for the month of June, alongside pearl and moonstone, alexandrite carries a weight of history and symbolism that few other gems can match. Its discovery in the 19th-century Russian Ural Mountains forged an immediate connection with the Imperial Court, imbuing it with a legacy of royalty and prestige. Beyond its aesthetic allure, the stone is steeped in lore, believed by many to promote balance, intuition, and adaptability. This article delves into the comprehensive history, geology, gemological properties, and cultural significance of alexandrite, exploring the science behind its mesmerizing color change and the reasons for its enduring value in fine jewelry.
History and Lore
The history of alexandrite is as dramatic as the gemstone's color change. Its story begins in the Ural Mountains of Russia during the 1830s, a region known for its rich deposits of precious minerals. The gem was first identified by the noted mineralogist Nils Gustaf Nordenskiöld, who recognized its unusual properties. In 1834, the stone was named in honor of the future Czar of Russia, Alexander II. This naming was not merely a tribute; it cemented the gem's status within the Russian aristocracy. The stone's signature colors—green and red—were the national military colors of the Russian Empire, further enhancing its appeal and prestige among the Czars and their court.
During the 19th and early 20th centuries, alexandrite became a symbol of Russian imperial power and fortune. Its rarity and unique appearance made it a prized possession, often featured in ornate jewelry worn by the elite. The gem’s association with the Imperial family helped it gain widespread recognition and desire across Europe.
Following the Russian Revolution, the primary sources of these prized Ural stones were largely depleted, making fine Russian alexandrite exceptionally rare. However, new deposits were later discovered in Sri Lanka, East Africa, and Brazil. While these new sources produced alexandrite, the fine material remained exceptionally rare and valuable. The gem's journey from a Russian imperial treasure to a globally recognized birthstone has solidified its place in history. Today, it is recognized not only as a June birthstone but also as the designated gem for the 55th wedding anniversary, adding to its significance as a gift for major life milestones. The lore surrounding the stone suggests it embodies the duality of its appearance, symbolizing a life of good and bad fortune, a belief that has persisted through its long history.
Geological Formation and Sources
Alexandrite is a variety of the mineral chrysoberyl, which forms under specific geological conditions involving beryllium and aluminum. The presence of chromium is the critical element responsible for the gem's signature color change; chromium ions absorb light in the yellow portion of the spectrum, allowing green and red wavelengths to pass through. However, the amount of chromium available in the geological environment where chrysoberyl forms is typically very low, which explains the extreme rarity of gem-quality alexandrite.
The original and most historically significant deposits were located in the Ural Mountains of Russia. These deposits, discovered in the 1830s, were alluvial, meaning the gems were weathered from their host rock and carried by water into gravels and riverbeds. The specific geological conditions in the Urals, including the presence of pegmatites and metamorphic rocks, allowed for the formation of these unique crystals. For decades, the Urals were the primary source of this coveted gem, but these mines are now largely exhausted, making fine Russian alexandrite a collector's item.
Modern sources of alexandrite have been identified in various locations around the world, though high-quality, facetable material remains rare. * Sri Lanka: This island nation has become a significant source of alexandrite, producing stones that often display a color change from green to a more violetish red. Sri Lankan alexandrite is known for its clarity and size, though the color shift may not always be as dramatic as the classic Russian material. * East Africa: Deposits in countries such as Tanzania and Zimbabwe have yielded alexandrite. These stones can exhibit a strong color change, often from a distinct green to a deep red. * Brazil: Brazilian deposits, particularly in the state of Minas Gerais, have produced alexandrite. The material from this region varies, with some stones showing a subtle color change and others a very pronounced one.
The rarity of alexandrite is compounded by the fact that even in these new localities, finding crystals large enough and of sufficient quality for faceting is a challenge. Consequently, the supply of natural alexandrite on the market is extremely limited, contributing to its high value.
Gemological Properties
Alexandrite possesses a unique set of physical and optical characteristics that define it as a member of the chrysoberyl family and distinguish it from other gemstones. Its durability and distinct optical phenomena make it a favorite among gemologists and jewelers.
The most critical property, of course, is its color-changing ability. This phenomenon is a result of a phenomenon known as pleochroism, combined with the specific way the human eye perceives color under different light sources. In daylight, which is rich in blue and green wavelengths, the stone appears greenish. In incandescent light, which is rich in red wavelengths, the stone appears reddish.
The following table summarizes the key gemological properties of alexandrite as documented in authoritative sources:
| Property | Description |
|---|---|
| Mineral | Chrysoberyl |
| Chemical Formula | BeAl₂O₄ |
| Color | Bluish green in daylight; purplish red in incandescent light |
| Mohs Hardness | 8.5 |
| Refractive Index | 1.746 to 1.755 |
| Specific Gravity | 3.73 |
| Birefringence | 0.008 to 0.010 |
Hardness and Durability: With a Mohs hardness of 8.5, alexandrite is exceptionally durable. This rating makes it suitable for all types of jewelry, including rings and bracelets that are subject to daily wear. It is harder than almost all other popular gemstones, second only to diamond, moissanite, and corundum (ruby and sapphire). This hardness means it is highly resistant to scratching and abrasion, though it should still be protected from sharp blows to avoid chipping or fracture.
Clarity and Inclusions: Natural alexandrite often contains inclusions. Unlike many other gems where inclusions are considered flaws, in alexandrite, they can sometimes be used as evidence of natural origin. A common inclusion pattern in Russian alexandrite is the "finger-print" or "jardin" inclusion, which resembles the whorls of a fingerprint. While eye-clean stones are prized, the presence of inclusions does not necessarily diminish the value as much as it might in other gems, provided the color change is strong.
Phenomena: Alexandrite can display two distinct phenomena: color change and the cat's-eye effect. The cat's-eye effect, or chatoyancy, occurs in cabochon-cut stones that contain parallel inclusions, creating a bright line that resembles a cat's eye. This makes alexandrite one of the few gemstones that can exhibit two separate and desirable optical phenomena.
Symbolism and Metaphysical Beliefs
Beyond its scientific marvels and historical prestige, alexandrite is deeply imbued with symbolic meaning and metaphysical lore. The gem's dramatic shift from green to red has led to a rich tapestry of interpretations across different cultures and eras.
The most prominent symbolism associated with alexandrite is balance and duality. The stone's two distinct colors represent the interplay of light and dark, joy and sorrow, and the material and spiritual worlds. It is believed to harmonize the mind and emotions, helping the wearer navigate life's contrasts with grace and adaptability. This idea of balance is central to its lore.
Alexandrite is also known as a stone of good fortune and luck. Its discovery by the Russian royal family, coinciding with the future Czar's coming of age, was seen as a powerful omen. This association with prosperity and positive change has persisted, and many believe that wearing alexandrite can attract success and ward off bad luck.
In modern metaphysical beliefs, alexandrite is linked to: * Intuition and Creativity: It is thought to enhance intuition and inspire creative thinking, making it a popular stone for artists and innovators. * Transformation and Renewal: As a June birthstone, it symbolizes adaptability and transformation, encouraging personal growth and the ability to embrace change. * Emotional Harmony: It is said to soothe emotional turmoil and promote a sense of inner peace and confidence.
Some traditions consider alexandrite a gemstone that harmonizes the mind and emotion. It is often associated with the crown chakra, believed to connect the wearer to higher states of consciousness. While these meanings are symbolic and not scientific, they contribute significantly to the gemstone's mystique and its appeal as a meaningful piece of jewelry.
Care and Cleaning
Given its exceptional hardness and durability, alexandrite jewelry is well-suited for everyday wear. However, proper care is essential to maintain its beauty and integrity over time. The gem's physical properties dictate the best practices for cleaning and storage.
Cleaning Instructions: The safest and most effective method for cleaning alexandrite is using warm, soapy water and a soft brush, such as a toothbrush. 1. Prepare a solution of lukewarm water and a few drops of mild dish soap. 2. Gently scrub the gemstone and its setting with the soft brush to remove any dirt, oil, or residue. 3. Rinse thoroughly with clean, lukewarm water to ensure all soap is removed. 4. Pat dry with a soft, lint-free cloth.
What to Avoid: * Ultrasonic Cleaners: These should be avoided, especially if the stone is set in a delicate or fracture-filled setting, as the intense vibrations can potentially damage the stone or its setting. * Harsh Chemicals: Avoid exposing alexandrite to bleach, ammonia, or other strong household chemicals, as they can damage the gem or the metal of its setting. * Abrasive Cleaners: Do not use abrasive powders or brushes, as they can scratch the surface of the gem, despite its hardness.
Storage: When storing alexandrite jewelry, it is important to keep it separate from other jewelry pieces to prevent scratching. While alexandrite is very hard, it can be scratched by harder gems like diamonds or sapphires. It is best to store it in a soft-lined jewelry box or a separate pouch. Additionally, it is advisable to protect alexandrite from sharp blows and extreme temperature changes, which could potentially cause internal fractures.
Conclusion
Alexandrite stands as a testament to the wonders of the natural world, combining scientific intrigue with profound historical and symbolic depth. Its unique color-changing property, a result of its specific geological formation, sets it apart as one of the most fascinating gemstones known to humanity. From its celebrated discovery in the Russian Ural Mountains and its enduring association with imperial power to its modern status as a cherished June birthstone, alexandrite has consistently captivated gem enthusiasts, jewelers, and collectors.
The gem's remarkable durability, characterized by a Mohs hardness of 8.5, ensures its longevity in fine jewelry, making it a practical choice for pieces intended for daily wear. Its rarity, both in its historical Russian deposits and in modern sources in Sri Lanka, East Africa, and Brazil, continues to drive its high market value and desirability. Whether valued for its scientific properties, its rich lore of balance and good fortune, or its sheer aesthetic beauty, alexandrite remains a pinnacle of gemological excellence. For those born in June or celebrating a 55th anniversary, it offers a gift that is not only beautiful but also rich in meaning and history, truly embodying the title of "emerald by day, ruby by night."