Alexandrite, the rarest and most intriguing of June’s birthstones, is a chrysoberyl variant known for its extraordinary ability to change color based on the light source. This remarkable phenomenon, often described as “emerald by day, ruby by night,” has made alexandrite a symbol of transformation, adaptability, and duality. While June is also associated with pearls and moonstone, it is alexandrite’s dramatic color shift that sets it apart, capturing the imagination of gemstone collectors, jewelers, and historians alike.
This article explores the scientific, historical, and cultural dimensions of alexandrite, drawing from authoritative gemological resources and historical accounts. It delves into the gem’s geological origins, color-changing properties, global sources, and symbolic significance. With a focus on authenticity and accuracy, this guide is tailored for gemstone enthusiasts, jewelry buyers, and students of gemology who seek to understand the rare beauty and complexity of this captivating birthstone.
History and Lore
Alexandrite was first discovered in the 1830s in the Ural Mountains of Russia, a region known for its rich mineral deposits. The gem was named after Czar Alexander II, who was then the heir to the Russian throne. According to some accounts, the discovery coincided with his 18-year-old birthday and his coronation, and the gem was said to exhibit a ruby-like red hue under the warm light of a candle — a color traditionally associated with celebration and regal power.
The gem’s naming and early history are, however, marked by some controversy. Some sources suggest that the first alexandrites discovered were not the purest or most vivid specimens and that the most prized stones were later found in other regions. Despite these uncertainties, the gem quickly became a favorite among European royalty and aristocracy, who admired its rarity and the way it seemed to "change" under different lighting conditions.
In 1912, alexandrite was officially recognized as one of the birthstones for June, alongside pearl and moonstone. By the late 20th century, it had also become the designated gemstone for the 55th wedding anniversary. This dual association with both a birth month and a milestone anniversary has further elevated its status in the world of fine jewelry.
Despite its historical significance, alexandrite has remained relatively obscure compared to other gemstones due to its extreme rarity. High-quality, large alexandrite crystals suitable for jewelry are exceedingly rare, making them some of the most valuable and sought-after stones in the market.
Geological Formation and Sources
Alexandrite is a color-change variety of chrysoberyl, a mineral with the chemical formula BeAl₂O₄. Its ability to shift color is due to trace amounts of chromium and sometimes vanadium, which alter the way the stone absorbs and reflects light. The presence of these elements is crucial to the “alexandrite effect,” the term used to describe the gem’s dramatic color transformation.
The gem forms in metamorphic rock environments, typically in areas where beryllium-rich and aluminum-rich minerals have interacted under high pressure and temperature conditions. These conditions are relatively rare, which contributes to the scarcity of alexandrite deposits.
Primary Mining Locations
While alexandrite was first discovered in the Ural Mountains of Russia, this region no longer produces high-quality material. Today, the primary sources of alexandrite include:
- Brazil: Brazilian alexandrite is known for its pale blue-green color in daylight and pale mauve in artificial light. Some specimens from this region contain internal inclusions where aluminum has been replaced by gallium, a unique geological feature.
- Sri Lanka: Alexandrite from Sri Lanka often exhibits an olive-green or yellowish-green color in daylight and a brownish-red in artificial light. These stones tend to have higher birefringence than those from Brazil or Zimbabwe.
- Zimbabwe: Zimbabwean alexandrite is known for its rich emerald-green color in daylight and a purplish-red in artificial light. These stones have a lower birefringence than Russian and Sri Lankan material but a higher refractive index than material from Brazil and Burma.
Each of these sources produces alexandrite with distinct color characteristics and gemological properties, allowing gemologists and collectors to identify the origin of a stone based on these traits.
Despite the availability of alexandrite in several countries, finding large, high-quality stones with a strong color change remains extremely rare. This scarcity has led to the development of synthetic alexandrite in laboratory settings, which can replicate the gem’s chemical composition and optical properties.
Gemological Properties
Alexandrite is not only visually striking but also scientifically fascinating. Its unique properties make it one of the most interesting and valuable gemstones in the world. Below is a detailed overview of its gemological characteristics:
Hardness and Durability
Alexandrite ranks at 8.5 on the Mohs scale of hardness, making it one of the hardest natural gemstones. This high hardness makes it suitable for use in everyday jewelry, although it does have a distinct cleavage along the {110} plane, which can make cutting and polishing more challenging. Care should be taken to avoid subjecting the stone to sudden impacts or sharp blows, particularly along the cleavage direction.
Color and the Alexandrite Effect
The most defining feature of alexandrite is its color change, or "alexandrite effect." This phenomenon occurs because the stone absorbs light differently depending on the light source. In daylight or fluorescent light, alexandrite typically appears green, blue-green, or yellow-green. Under incandescent or candlelight, it shifts to red, raspberry red, or purplish-red.
The intensity of the color change is a key factor in determining a stone’s value. The degree of color change is measured as a percentage, ranging from 5% to 100%. Stones with a higher percentage of color change are more valuable and are considered the most desirable.
In addition to the color change, alexandrite exhibits strong pleochroism, meaning it can display different colors when viewed from different angles. This property is particularly noticeable in daylight, where the gem may appear green from one angle and yellow-orange from another.
Optical and Physical Properties
Alexandrite has a refractive index (RI) of 1.745–1.759, a birefringence of 0.008–0.010, and a dispersion of 0.015. These optical properties contribute to its brilliance and sparkle when cut and polished.
The gem is typically transparent to translucent and has a vitreous (glassy) luster. Its specific gravity ranges from 3.68 to 3.80, which is relatively high for a transparent gemstone.
Alexandrite also exhibits weak fluorescence under both short-wave and long-wave ultraviolet light, glowing in a faint red color. This property can be used as a diagnostic tool for gemologists when identifying the stone.
Symbolism and Metaphysical Beliefs
Throughout history, alexandrite has been associated with various symbolic meanings and metaphysical properties. In ancient times, it was believed to bring good fortune and protection to its wearer. The gem was also thought to enhance adaptability and flexibility, qualities that align with its ability to change color.
In modern times, alexandrite is often linked to themes of transformation, balance, and duality. These associations make it a popular choice for those seeking a gemstone that reflects the complexity of life’s transitions. The stone is also believed to promote emotional healing and clarity of thought.
Alexandrite is also associated with the heart chakra in metaphysical practices. It is thought to help open the heart to love, compassion, and forgiveness, while also encouraging personal growth and self-awareness.
Despite these beliefs, it is important to note that metaphysical properties are not scientifically proven. They are often based on cultural traditions and personal experiences rather than empirical evidence. Nonetheless, many people find comfort and inspiration in the symbolic meanings of alexandrite.
Care and Cleaning
Due to its high hardness, alexandrite is relatively durable and can be worn in everyday jewelry. However, to preserve its beauty and integrity, it is important to follow proper care and cleaning guidelines.
Cleaning Recommendations
Alexandrite can be cleaned with a soft brush and warm, soapy water. A mild detergent, such as dish soap, can be used to gently remove dirt and debris. The stone should be rinsed thoroughly and dried with a soft cloth to avoid water spots.
Ultrasonic and steam cleaners are generally safe for alexandrite, provided the stone is not treated or enhanced in a way that might be affected by high-frequency vibrations or heat. As with all gemstones, it is important to avoid exposing alexandrite to harsh chemicals, such as bleach or ammonia, which can damage the stone or its setting.
Storage and Handling
Alexandrite should be stored separately from other gemstones to prevent scratching or abrasion. Because of its cleavage, it is also advisable to avoid stacking stones on top of each other or subjecting the gem to pressure.
When wearing alexandrite jewelry, it is best to avoid activities that involve physical impact or exposure to abrasive materials. As with all precious stones, regular inspection for loose settings or damage is recommended to ensure the longevity of the piece.
Conclusion
Alexandrite is a gemstone of rare beauty and scientific wonder. Its ability to change color in different light sources makes it one of the most captivating and sought-after gems in the world. From its discovery in the Ural Mountains to its current status as an official birthstone for June, alexandrite has captivated the imagination of gemstone lovers and historians alike.
With a hardness of 8.5, a refractive index of 1.745–1.759, and a rich history of symbolism, alexandrite is not only a gemstone of extraordinary beauty but also one of exceptional scientific and cultural significance. Whether admired for its color-changing properties, its geological rarity, or its symbolic meaning, alexandrite continues to inspire and enchant those who encounter it.
As a birthstone, alexandrite represents the dynamic and transformative nature of life, making it a meaningful and powerful choice for those born in June. Its rarity, beauty, and unique properties ensure that it will remain a cherished gemstone for generations to come.