The realm of dark blue gemstones is rich with history, symbolism, and geological wonder. While sapphire is most prominently recognized as the dark blue birthstone, particularly for the month of September, a diverse array of other gems also exhibit captivating shades of blue, offering a spectrum of choices for those seeking this evocative color. This article delves into the world of dark blue gemstones, exploring their origins, properties, historical significance, and the meanings attributed to them across cultures.
A History Rooted in Reverence
The allure of blue gemstones dates back millennia. Sapphire, belonging to the corundum family—second in hardness only to diamond—has been prized for centuries. Sources indicate that sapphires were worn by biblical King Solomon, highly regarded by the Jewish people, and even hidden from invading Romans during the siege of Jerusalem. Lapis lazuli, a deep blue metamorphic rock, also boasts a long and storied past, serving as the original eleventh stone of Aaron’s breastplate before being superseded by sapphire as the official September birthstone by the Gemological Institute of America (GIA).
Beyond these ancient connections, blue topaz has a history stretching back to the Greek Islands over two millennia ago. Even diamonds, typically known for their colorless brilliance, can occur in blue shades, though these “fancy” colored diamonds command exceptionally high prices. The reverence for blue stones is deeply ingrained in human history, often associated with royalty, spirituality, and protection.
Geological Origins and Global Sources
The formation of these dark blue gemstones is a testament to the powerful forces within the Earth. Sapphires, composed of aluminum oxide, form over millions of years under conditions of intense heat and pressure deep within the Earth’s crust. These gems are mined in various locations worldwide, including Russia, Nigeria, and the United States.
Blue topaz, a silicate mineral containing silicon, oxygen, fluorine, and aluminum, is also mined globally, with sources in Russia, Nigeria, China, and the United States. While naturally occurring blue topaz is rare, the market is largely supplied by stones that have been treated with radiation and heat to achieve their vibrant blue hues.
Other blue gemstones, like zircon, are found in diverse geological settings. Tanzanite, a relatively recent discovery, is mined from a small area in Tanzania and is notable for its trichroism—displaying blue, violet, and burgundy depending on the crystal orientation. Even amber, typically associated with warm hues, can rarely be found in a blue variety, exclusively in the Dominican Republic.
Gemological Properties: A Spectrum of Characteristics
The gemological properties of dark blue gemstones vary considerably, influencing their durability, brilliance, and value. Sapphire’s exceptional hardness (9 on the Mohs scale) makes it highly resistant to scratching, ensuring its longevity. The rich dark blue color of sapphires is attributed to the presence of trace amounts of iron and titanium, which absorb light in the red and orange-yellow spectrum, reflecting blue light. The most desirable shade is often referred to as “cornflower blue,” a medium-dark tone.
Blue topaz also scores well on the Mohs scale, with a hardness of 8, making it relatively durable. However, London blue topaz, a darker shade, is noted to be less durable and more susceptible to damage than other varieties. The color in topaz is often achieved through irradiation and heat treatment.
Zircon, another blue gemstone, can rival diamond in its radiance, but its properties differ. Lapis lazuli, being a rock rather than a single mineral, has a different set of characteristics, lacking the same hardness as corundum or topaz.
Here's a comparative table of some key properties:
| Gemstone | Chemical Composition | Hardness (Mohs) | Color Range |
|---|---|---|---|
| Sapphire | Aluminum Oxide (Al₂O₃) | 9 | Dark blue to light blue, various other hues |
| Blue Topaz | Silicate (with F, Al) | 8 | Light to dark blue |
| Blue Zircon | Zirconium Silicate | 6.5-7.5 | Various shades of blue |
| Lapis Lazuli | Lazurite | 5-6 | Deep blue |
Symbolism and Metaphysical Beliefs
Throughout history, dark blue gemstones have been imbued with symbolic meaning. Sapphires have long been associated with wisdom, loyalty, and nobility. In the Middle Ages, blue topaz was believed to heal mental disorders and physical ailments, even preventing death. Egyptians wore topaz as an amulet for protection against injury.
Blue topaz, in general, is considered a stone of fidelity and love, believed to calm tempers, cure insanity, improve vision, and relieve asthma. Some believe it aids digestion and stimulates metabolism. Lapis lazuli, with its celestial hue, was linked to hopes and dreams, evoking the vastness of the heavens.
Dark blue gemstones are often thought to promote inner peace, enhance intuition, and relieve stress. Their calming colors are believed to foster open communication and deepen emotional connections. These beliefs, while not scientifically proven, contribute to the enduring appeal of these stones.
Care and Cleaning
Maintaining the beauty of dark blue gemstones requires appropriate care. Sapphire’s hardness makes it relatively resistant to scratching, but it should still be protected from harsh impacts. Blue topaz, while durable, requires more caution, particularly London blue topaz, which is more prone to chipping or scratching.
Generally, cleaning these gemstones can be done with warm, soapy water and a soft brush. Avoid ultrasonic cleaners and harsh chemicals, as these can damage the stones. Regular cleaning will help preserve their brilliance and luster.
Beyond Sapphire: A Diverse Palette
While sapphire reigns as the most recognized dark blue birthstone, the variety of options is extensive. From the rich depths of lapis lazuli to the vibrant hues of blue topaz and the rare trichroism of tanzanite, a spectrum of blue gemstones awaits discovery. Other options include blue zircon, agate, diamond, beryl, garnet, jade, spinel, and tourmaline, each offering unique characteristics and appeal.
Conclusion
Dark blue gemstones represent a captivating intersection of geological processes, historical significance, and cultural symbolism. Sapphire, as the primary dark blue birthstone, embodies enduring beauty and strength. However, the broader world of blue gemstones offers a diverse palette of options, each with its own unique story and allure. Whether sought for their aesthetic appeal, metaphysical properties, or historical connections, these stones continue to fascinate and inspire.