For those born in the final month of the year, December offers a trio of birthstones that are as varied in their origins and properties as they are unified in their symbolic significance. While many months are associated with a single gem, December is uniquely represented by three distinct stones: turquoise, zircon, and tanzanite. Each possesses a rich history, unique geological story, and deep cultural lore. Turquoise, the traditional and ancient birthstone, has been cherished for millennia for its captivating sky-blue color and its association with protection and good fortune. Zircon, one of the oldest minerals on Earth, provides a brilliant alternative, often mistaken for diamond, with a history that spans centuries. The newest member of this trio, tanzanite, is a modern marvel, discovered only in the 20th century and celebrated for its intense violet-blue hue and remarkable rarity. Together, these stones capture the essence of December—a month of cold clarity, festive celebration, and the promise of new light. This article explores the history, geology, symbolism, and care of these three exceptional gems, providing a comprehensive guide for enthusiasts, collectors, and anyone captivated by the beauty of December’s birthstones.
History and Lore: A Journey Through Time
The history of December’s birthstones is a tale of ancient traditions, rediscovery, and modern innovation. Turquoise stands as the most ancient of the three, with a legacy that stretches back to civilizations that revered it as a talisman of power and protection. Its journey from the deserts of the world to the hands of kings and warriors is a testament to its enduring appeal. Zircon’s story is equally long, though its identity has been clouded by confusion and misidentification for much of its history. It is a gem that has witnessed the formation of the Earth itself and has been part of human adornment for thousands of years. In stark contrast, tanzanite’s history is brief but dramatic, emerging from a single, remote location in Africa to capture the global imagination in the late 20th century. The selection of these three stones as December’s birthstones is not arbitrary; it reflects a blend of tradition, geological rarity, and cultural significance.
The Ancient Legacy of Turquoise
Turquoise is arguably one of the oldest known gemstones in human history, with a documented use that predates recorded civilization. It has been found in ancient Egyptian tombs, dating back to 3000 BCE, where it was used in intricate jewelry and funerary masks, most famously in the burial goods of Tutankhamun. The Egyptians called it mefkat, which translates to “joy” or “delight,” and prized it for its celestial color, which they associated with the heavens and the divine. They believed it possessed the power to protect the wearer from harm and to bring good health and fortune.
The stone’s influence spread across the ancient world. In ancient Persia (modern-day Iran), turquoise was a national gemstone, used extensively in the art of inlaying and mosaic work. The Persian word for turquoise, firoza, means “victory,” reflecting the stone’s association with protection in battle and its role as a bringer of triumph. It was believed to ward off the “evil eye” and was often set into swords, horse bridles, and shields.
For the Native American peoples of the Southwestern United States, turquoise is a sacred stone, deeply intertwined with their spiritual beliefs and cultural identity. The Pueblo, Navajo, Zuni, and Apache tribes have mined and worked with turquoise for centuries. For them, the stone represents the sky, water, and the earth’s connection to the heavens. It is used in ceremonial objects and jewelry, not merely for ornamentation, but as a conduit for spiritual power and a symbol of life and health. The stone’s color is said to change with the health of the wearer, turning pale when illness is present and vibrant when the wearer is in good health.
Zircon: The Misunderstood Heirloom
Zircon’s history is one of longevity and misconception. It is one of the oldest minerals on Earth, with zircon crystals found in Australian sediments that are over 4.4 billion years old, providing geologists with a window into the planet’s earliest formation. However, its use in jewelry is often overshadowed by its confusion with other, more famous gems. For centuries, the term “zircon” was frequently used interchangeably with “jacinth,” a hyacinth-colored variety, and more damagingly, it was confused with synthetic cubic zirconia, a diamond simulant developed in the 1970s. This confusion led to zircon being unfairly perceived as a cheap imitation rather than a precious gemstone in its own right.
Despite this, zircon has a noble history. In the Middle Ages, it was believed to promote sleep, bring prosperity, and ward off evil spirits. Its high refractive index and strong dispersion (fire) made it a popular diamond substitute in Victorian-era jewelry, particularly in the 19th century. While it has never achieved the same level of fame as diamond or sapphire, zircon has always been appreciated by connoisseurs for its exceptional brilliance and fire, which rival those of diamond.
Tanzanite: A Modern Discovery
Tanzanite’s history is remarkably short, beginning with a single, dramatic event in 1967. A Maasai herder discovered a cluster of brilliant blue crystals in the Merelani Hills of northern Tanzania, near the base of Mount Kilimanjaro. The stones were soon identified as a variety of the mineral zoisite and were given the name tanzanite in honor of their country of origin. The discovery was quickly commercialized, and the gemstone’s intense violet-blue color, which ranges from ultramarine to lavender, captivated the international jewelry market.
The Tiffany & Co. jewelry company recognized tanzanite’s potential and launched a major marketing campaign in 1968, making it a household name almost overnight. Its rarity is a key part of its allure; tanzanite is found in only one known location in the world, making it thousands of times rarer than diamond. This geographic limitation has led to its nickname as “the gem of a generation,” with some geologists speculating that the deposits may be exhausted within a few decades. Its rapid rise to prominence and its unique color make it a distinctly modern birthstone, representing the innovation and discovery of the late 20th century.
The Birthstone Designation
The modern list of birthstones, which includes these three gems for December, was standardized by the American National Association of Jewelers (now Jewelers of America) in 1912. This list was updated in 1952 and again in 2002 and 2016, with tanzanite being added to the December list in 2002. The inclusion of tanzanite alongside the traditional turquoise and the classic zircon reflects the evolution of the birthstone tradition, embracing new discoveries while honoring ancient practices. This trio offers a range of colors and histories, providing a unique choice for those born in the last month of the year.
Geological Formation and Sources
Understanding the genesis of a gemstone is key to appreciating its value and uniqueness. Turquoise, zircon, and tanzanite are formed through vastly different geological processes and are sourced from distinct, often limited, regions of the world. Their formation stories are as compelling as their histories, explaining their rarity, color, and physical characteristics.
Turquoise: A Hydrated Mineral of the Arid Lands
Turquoise is not a single mineral but a hydrated phosphate of copper and aluminum, with the chemical formula CuAl₆(PO₄)₄(OH)₈·4H₂O. Its formation is a secondary process, occurring in arid or semi-arid regions where acidic, copper-rich water percolates through rocks containing aluminum and phosphorus. Over long periods, this process creates nodules or veins of turquoise within the host rock, often a porous sandstone or limestone. The presence of copper imparts the classic blue color, while iron imparts a greenish hue. The quality of turquoise is heavily influenced by the host rock, which can be left intact in the matrix, creating a distinctive and often prized pattern.
The world’s most significant sources of turquoise are located in the Southwestern United States (Arizona, New Mexico, Nevada, and Colorado), Iran (the historic source of Persian turquoise), Tibet, and China. The United States is particularly renowned for its diverse and high-quality deposits, with famous localities such as the Sleeping Beauty mine in Arizona (known for its pure sky-blue color) and the Bisbee mine (known for its rich blue with a chocolate-brown matrix). Iranian turquoise, often called “Persian turquoise,” is celebrated for its even, robin’s-egg blue color and is historically the most prized. The limited geographic distribution of high-quality turquoise deposits contributes to its enduring value and cultural significance.
Zircon: An Ancient Mineral of Igneous and Metamorphic Rocks
Zircon (zirconium silicate, ZrSiO₄) is a mineral that forms in the cooling of magma, primarily in igneous rocks like granite and syenite, and in metamorphic rocks such as gneiss and schist. It is highly resistant to weathering and chemical breakdown, which is why it is found in sedimentary deposits and is used in radiometric dating of rocks. The gem-quality zircon used in jewelry is typically sourced from placer deposits, where it has been eroded from its original host rock and concentrated by water or wind action.
The primary sources of gem zircon include Thailand, Sri Lanka, Australia, and the United States (particularly in the states of Montana and North Carolina). Australian zircon, often found in the heavy mineral sands of the east coast, is known for its rich colors. Sri Lankan and Thai zircon are frequently heat-treated to enhance their color, a common and accepted practice in the gem trade. The mineral’s high specific gravity and durability make it a common component of heavy mineral sands, which are mined for various industrial uses, with the gem-quality crystals being separated and cut for jewelry.
Tanzanite: A Gem of a Single Source
Tanzanite is a variety of the mineral zoisite, with the chemical formula Ca₂Al₃(SiO₄)₃(OH). Its formation is linked to a unique geological event: the metamorphism of limestone by heat and pressure from igneous intrusions, a process that occurred during the formation of the East African Rift. This specific combination of elements and conditions, which created the vanadium that gives tanzanite its color, is believed to have occurred only in a small area of the Merelani Hills in Tanzania.
The mining of tanzanite is concentrated in four small blocks (A, B, C, and D) near Mount Kilimanjaro. Block C is the most productive. The mining process is often challenging, with some operations involving small-scale, artisanal mining. The geographic limitation of this single source is a defining characteristic of tanzanite, contributing to its rarity and market value. Unlike turquoise and zircon, which are found in multiple locations worldwide, tanzanite’s origin is fixed, making it a true “gem of a generation” with a finite supply.
Gemological Properties
The physical and optical properties of a gemstone determine its durability, brilliance, and suitability for jewelry. Turquoise, zircon, and tanzanite differ significantly in these characteristics, which influences how they are cut, set, and cared for. The following table summarizes their key gemological properties, based on established standards.
| Property | Turquoise | Zircon (Blue) | Tanzanite |
|---|---|---|---|
| Chemical Formula | CuAl₆(PO₄)₄(OH)₈·4H₂O | ZrSiO₄ | Ca₂Al₃(SiO₄)₃(OH) |
| Crystal System | Triclinic | Tetragonal | Orthorhombic |
| Hardness (Mohs) | 5 - 6 | 6.5 - 7.5 | 6 - 7 |
| Refractive Index | 1.610 - 1.650 | 1.925 - 2.015 | 1.691 - 1.700 |
| Specific Gravity | 2.60 - 2.90 | 4.60 - 4.70 | 3.35 |
| Luster | Waxy to subvitreous | Adamantine | Vitreous |
| Color | Sky blue to blue-green; can be matrix-included | Colorless, yellow, brown, blue, green, red | Violet-blue to ultramarine |
| Transparency | Opaque to translucent | Transparent to translucent | Transparent |
| Pleochroism | None | Weak to strong | Strong (blue, violet, burgundy) |
Hardness and Durability: Zircon is the hardest of the three, with a Mohs hardness of 6.5 to 7.5, making it suitable for rings and daily wear, though it can be brittle. Tanzanite, with a hardness of 6 to 7, is also suitable for jewelry but is more susceptible to chipping and scratching than zircon. Turquoise, with the lowest hardness of 5 to 6, is the most delicate. It is prone to scratching and can be damaged by chemicals, heat, and even prolonged exposure to skin oils and cosmetics. For this reason, turquoise jewelry is often set in protective settings and is best suited for earrings, pendants, and occasional wear.
Color and Optical Properties: The color of these gems is a defining feature. Turquoise’s blue color comes from copper, and its hue can vary based on the specific mineral content and the presence of the host rock matrix. Zircon’s blue color is typically achieved through heat treatment of brown zircon, a process that is permanent and stable. The blue variety of zircon is prized for its exceptional brilliance and fire, which can rival that of diamond. Tanzanite’s color is its most celebrated attribute. It exhibits strong pleochroism, meaning it shows different colors when viewed from different crystal directions—typically blue, violet, and burgundy. Gem cutters must orient the stone carefully to present the desired blue-violet hue in the final gem. Most tanzanite is heat-treated to enhance its color, a process that mimics the natural conditions that would have occurred over millions of years.
Clarity and Inclusions: Zircon and tanzanite are typically faceted and valued for their clarity. Zircon can contain inclusions, but clean stones are common. Tanzanite is often found with inclusions, and its clarity can vary. Turquoise is almost always opaque and is valued for its uniform color and the pattern of its matrix. High-quality turquoise is judged by its color, consistency, and the absence of heavy pitting or mottling.
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, gemstones have long been imbued with symbolic meaning and metaphysical power. Turquoise, zircon, and tanzanite each carry a rich tapestry of beliefs, reflecting their diverse origins and cultural histories. These associations continue to resonate with modern wearers, adding a layer of personal significance to the jewelry they choose.
Turquoise: The Stone of Protection and Fortune
Turquoise is universally regarded as a stone of protection, good fortune, and healing. Across cultures, it has been believed to safeguard the wearer from harm, whether physical, spiritual, or emotional. In ancient Persia, it was worn as an amulet against unnatural death and was thought to change color to warn of impending danger. For Native American cultures, it is a sacred stone that connects the physical and spiritual worlds, used in rituals and ceremonies to bring balance and health.
Metaphysically, turquoise is associated with the throat and heart chakras, promoting honest communication, emotional balance, and inner calm. It is said to foster creativity, attract prosperity, and enhance intuition. Many believe it has a soothing energy that can alleviate stress and depression, making it a stone of tranquility and well-being. Its connection to the sky and water symbolizes the flow of life, purification, and the infinite.
Zircon: The Stone of Wisdom and Prosperity
Zircon has a long history of being associated with wisdom, honor, and prosperity. In the Middle Ages, it was believed to promote restful sleep, ward off evil spirits, and bring wealth to its owner. It was also thought to help with bone and lung ailments. Different colors of zircon carry different meanings; for example, yellow zircon is linked to wisdom and clarity, while red zircon (hyacinth) is associated with passion and vitality.
Metaphysically, zircon is considered a stone of grounding and protection. It is believed to enhance spiritual awareness and facilitate a connection with higher realms of consciousness. Its brilliant light is said to dispel negative energy and bring about a sense of peace and clarity. For those seeking to overcome obstacles and achieve their goals, zircon is thought to provide the mental fortitude and focus needed for success.
Tanzanite: The Stone of Transformation and Intuition
As a modern gem, tanzanite’s metaphysical beliefs are more contemporary but no less powerful. It is often called the “stone of transformation,” believed to facilitate a higher consciousness, intuition, and spiritual perception. Its intense violet-blue color is associated with the crown and third-eye chakras, which are linked to intuition, vision, and spiritual connection.
Tanzanite is said to help with overcoming trauma and grief, promoting a sense of calm and mindfulness. It is believed to open the mind to new possibilities and encourage a more compassionate and empathetic outlook. Some also associate it with enhanced communication and the ability to express one’s truth. Its rarity and unique color are thought to symbolize the preciousness of life and the importance of embracing change.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of any gemstone jewelry. Due to their differing physical properties, turquoise, zircon, and tanzanite require specific cleaning and storage methods to prevent damage.
Turquoise: Gentle and Protective Care
Turquoise is the most delicate of the three stones and requires the most careful handling. It is porous and can absorb chemicals, oils, and lotions, which can cause discoloration and damage over time. To clean turquoise jewelry, use only a soft, dry cloth. If necessary, a mild, pH-neutral soap and lukewarm water can be used, but the stone must be dried immediately and thoroughly. Avoid ultrasonic cleaners, steam cleaners, and harsh chemicals, as these can irreparably damage the stone and any stabilizing treatments it may have undergone.
Store turquoise jewelry separately from other pieces to prevent scratching. It is also advisable to keep it away from direct sunlight and extreme heat, as prolonged exposure can cause fading and cracking. Applying lotions, perfumes, and hairsprays before putting on turquoise jewelry will help minimize exposure to chemicals.
Zircon: Handling with Care
Zircon, despite its hardness, is brittle and can be prone to chipping or cracking if struck. It is also sensitive to heat, which can cause it to fracture. For cleaning, warm soapy water and a soft brush are safe. Avoid ultrasonic cleaners, especially for stones with inclusions, as the vibrations can cause fractures. Steam cleaning is also not recommended.
When storing zircon jewelry, it is best to keep it in a soft cloth or a separate compartment in a jewelry box to prevent it from being scratched by harder stones like diamond or scratched by softer stones. Due to its brittleness, it is not ideal for rings that are worn daily, especially in settings that expose the stone to impact.
Tanzanite: A Delicate Beauty
Tanzanite, with a hardness of 6 to 7, is moderately durable but can be scratched and is susceptible to chipping due to its cleavage properties. It is also heat-sensitive, so it should not be exposed to high temperatures. The safest method for cleaning tanzanite is with warm, soapy water and a soft brush. It is crucial to avoid ultrasonic and steam cleaners, as the vibrations and heat can cause internal fractures and damage the stone.
When setting tanzanite in jewelry, jewelers often use protective settings like bezels to minimize the risk of impact. It is also important to note that many tanzanite gems are treated with a thin coating or oil to fill surface-reaching fractures; these treatments can be damaged by harsh cleaning methods. Always consult a professional jeweler for cleaning and maintenance, especially for valuable pieces.
Conclusion
December’s birthstones—turquoise, zircon, and tanzanite—offer a remarkable journey through time, geology, and human belief. Turquoise, with its ancient legacy and protective symbolism, connects us to the earliest civilizations and the sacred traditions of the Americas. Zircon, an ancient mineral with a misunderstood history, provides a brilliant and fiery alternative with a connection to the very formation of our planet. Tanzanite, a product of a unique and recent geological event, represents modern discovery and the fleeting beauty of a rare gem. Together, they provide a diverse and meaningful choice for those born in the final month of the year, each stone telling a different story of color, resilience, and significance. Whether chosen for its historical depth, its brilliant sparkle, or its captivating hue, any of these three gems serves as a beautiful and enduring emblem of December.