Turquoise stands as one of the most ancient and recognizable gemstones in human history. Its distinctive blue-to-green hue, often veined with a unique matrix, has captivated civilizations for millennia. As one of the three traditional birthstones for December, alongside tanzanite and zircon, turquoise offers a unique palette of color and lore that resonates with modern gemstone enthusiasts. This article explores the rich history, geological origins, gemological properties, and cultural significance of this semi-translucent to opaque gem, drawing exclusively from verified gemological and historical sources to provide a comprehensive overview for collectors, jewelers, and students of gemology.
History and Lore
The history of turquoise is as deep as the mines from which it is extracted. This December birthstone has been cherished for millennia, with evidence of its use dating back to ancient civilizations. The pharaohs and other rulers of ancient Egypt adorned themselves with turquoise, integrating it into their regalia and burial artifacts. Chinese artisans were also early adopters, carving the stone more than 3,000 years ago.
Beyond its ornamental use, turquoise was imbued with powerful protective and beneficial properties. Across various cultures, it was believed to guarantee health and good fortune. From the 13th century onward, a specific European belief held that the gemstone could protect the wearer from falling, particularly from horses, and would shatter into several pieces as a warning of an impending disaster. Hindu mystics attached a different ritual to the stone, maintaining that seeing a turquoise after beholding the new moon would ensure fantastic wealth.
The stone also played a vital role in the spiritual and practical lives of Native American tribes. The Apache, for instance, believed that turquoise could be found by following a rainbow to its end, linking the gemstone directly to celestial phenomena. In the Hindu religion, turquoise is not listed among the nine gems of the navaratna, but other gemstones like zircon and hessonite garnet are, illustrating the region's deep gemological traditions. In more recent history, the Victorians developed a fondness for blue zircon, but turquoise remained a staple in jewelry, often set in silver, a combination that became iconic in Southwestern American design. The stone is also said to impart peace to those who wear it, adding a layer of spiritual calm to its list of attributes.
Geological Formation and Sources
Turquoise is a hydrous phosphate mineral containing copper and aluminum. Its formation requires a specific geological environment where acidic, copper-rich water percolates through rocks containing aluminum and phosphorus, leading to the precipitation of the mineral. The resulting gem is semi-translucent to opaque and frequently contains veins of matrix—the remnants of the host rock in which it formed.
The geographical sources of turquoise are diverse and historically significant. The Nishapur district of Iran has been a mining center for more than 1,000 years, producing some of the most prized turquoise in the world. The even-colored, intense blue from this region is so distinctive that it has given rise to descriptive terms like “robin’s egg blue,” “sky blue,” and “Persian blue.” In the gem trade, these terms are now used to describe any turquoise of this specific color, regardless of its actual geographic origin.
In the United States, turquoise mining has a rich history. New Mexico was the largest producer until the 1920s, but today, the majority of U.S. production comes from Arizona and Nevada. Mines in these states bear evocative names such as Dry Creek, Easter Blue, Emerald Valley, and Fox. The Kingman mine in Arizona is a historically important source known for its intense blue turquoise. Another notable Arizona mine, the Sleeping Beauty mine, was a prolific producer for over four decades but is now closed to turquoise mining.
Globally, the landscape of production has shifted. Today, China is the world’s largest producer of this December birthstone. Most of the gem-quality turquoise currently mined there originates from Hubei Province in central China.
Gemological Properties
Understanding the physical and chemical properties of turquoise is essential for its identification, care, and valuation. As an opaque gem, its color is its most defining characteristic, ranging from blue to green. The presence of copper imparts the blue hue, while iron content tends to shift the color toward green. The matrix, or the host rock remnants, can appear as a black, brown, or golden web-like pattern, adding to the stone’s unique character.
Turquoise Gemological Properties
| Property | Description |
|---|---|
| Chemical Formula | Hydrous copper aluminum phosphate |
| Crystal System | Triclinic (but typically found in massive form) |
| Hardness (Mohs Scale) | 5 to 6 |
| Refractive Index | Not typically measured due to opacity |
| Specific Gravity | 2.60 to 2.90 |
| Luster | Waxy to subvitreous |
| Transparency | Semi-translucent to opaque |
| Treatments | Dyeing, stabilization with epoxy or acrylic resin |
The Mohs hardness of 5 to 6 indicates that turquoise is relatively soft compared to many other gemstones. This makes it susceptible to scratching and abrasion, which is a critical consideration for jewelry design and wear. To improve durability, appearance, and polish, some turquoise is treated. Common treatments include dyeing to enhance or uniform color, and stabilization—a process where an epoxy or acrylic resin is added to the stone. Stabilization increases hardness and improves color consistency. According to gemological sources, the resulting color from such treatments is permanent, and there are no additional durability concerns post-treatment.
Symbolism and Metaphysical Beliefs
The symbolic power of turquoise is as varied as the cultures that have prized it. Across history, it has been more than a decorative element; it was a talisman, a protector, and a conduit to spiritual wealth. In ancient Egypt, it was a symbol of rebirth and protection in the afterlife. The protective belief from medieval Europe—that it could warn of danger by breaking—highlights its role as a physical guardian.
In Hindu tradition, while turquoise itself is not part of the navaratna (nine gems), the concept of gemstone synergy is present. The navaratna includes other December birthstones like zircon and garnet, and when worn together, these gems are believed to protect the wearer and confer wealth, wisdom, and good health. This illustrates a broader cultural belief in the interconnected powers of gemstones.
For the Apache people, the link between turquoise and the rainbow imbued the stone with a connection to the heavens and good fortune. The belief that it could be found at a rainbow’s end suggests a treasure of immense value and divine origin. Furthermore, the stone is associated with imparting peace, offering a calming influence to its wearer. These metaphysical beliefs, while not scientifically verifiable, form a crucial part of the gemstone’s enduring appeal and cultural legacy.
Care and Cleaning
Given its relative softness and potential for treatment, turquoise requires specific care to maintain its beauty and integrity. The Mohs hardness of 5 to 6 means it can be scratched by harder materials, including dust and other gemstones. It is also porous, especially if untreated, making it susceptible to absorbing liquids, chemicals, and cosmetics, which can lead to discoloration or damage.
For daily wear, jewelry settings should be protective. Turquoise is best set in earrings or pendants, where it is less likely to be knocked or abraded. While not recommended for daily wear in a ring, it can be used for special-occasion rings if set in a protective mounting (such as a bezel setting) and handled with care.
Cleaning turquoise should be done gently. The recommended method is to use warm, soapy water and a soft brush. It is imperative to avoid ultrasonic cleaners and steam cleaners, as the vibrations and heat can damage the stone, especially if it has been stabilized or dyed. After cleaning, the gem should be dried thoroughly with a soft, lint-free cloth. It is also advisable to avoid exposing turquoise to prolonged bright light or high heat, as these can potentially alter the color of some treated stones, though the sources indicate that turquoise itself is generally stable.
Conclusion
Turquoise remains a cornerstone of December's birthstone trio, celebrated for its captivating blue-green color, ancient history, and rich cultural symbolism. From the royal tombs of Egypt to the mines of Arizona and Iran, its journey through human history is a testament to its enduring value. While its softness demands careful handling and setting, its unique beauty and the deep lore surrounding it make it a cherished gemstone for collectors and jewelry lovers alike. Whether valued for its historical significance, its aesthetic appeal, or its believed metaphysical properties, turquoise continues to be a gemstone of profound beauty and meaning.