For individuals born in December, the birthstone options are as varied and captivating as the winter month itself. December is uniquely associated with three distinct gemstones: turquoise, zircon, and tanzanite. Each possesses a unique geological origin, a rich historical tapestry, and a spectrum of symbolic meanings that have evolved over centuries. While turquoise has been revered for millennia, zircon offers a brilliant alternative with a history intertwined with the diamond, and tanzanite represents a modern marvel discovered in the 20th century. This article delves into the intricate world of these three birthstones, exploring their formation, gemological properties, historical significance, and the cultural beliefs that have cemented their place as symbols of December. By examining the scientific data and historical accounts available, we can appreciate why these stones are chosen to represent the final month of the year, offering wearers a connection to both ancient tradition and contemporary discovery.
History and Lore
The concept of birthstones has deep roots, evolving from ancient beliefs about the twelve stones on the High Priest’s breastplate in the Book of Exodus. Over time, these stones became associated with zodiac signs and, eventually, calendar months. The modern birthstone list, standardized by the National Association of Jewelers (now Jewelers of America) in 1912, has undergone several revisions to include new discoveries and cultural preferences. The December stones, in particular, have seen significant updates, reflecting a blend of ancient tradition and modern gemology.
Turquoise holds the distinction of being one of the oldest known gemstones in human history. Its use as a gemstone spans thousands of years, with archaeological evidence pointing to its significance in ancient cultures across the globe. In the Southwestern United States, Native American tribes were using turquoise over 2,000 years ago, creating intricate beads, pendants, inlay work, and small sculptures. This ancient artistry highlights the stone’s deep cultural integration, where it was not merely an ornament but a medium for artistic and spiritual expression. The stone’s enduring presence in Southwestern culture underscores its historical continuity and symbolic power.
Zircon, while not as ancient in its documented use as turquoise, has a storied history that is often intertwined with the diamond. For centuries, high-quality zircon was mistaken for diamond due to its exceptional brilliance and fire. This misidentification led to its inclusion in royal crowns and jewelry, where its diamond-like properties were prized. The stone’s journey to becoming a recognized December birthstone is more recent, with its addition to most birthstone lists occurring in 1952. At that time, topaz was the primary November birthstone, and zircon was introduced as a December alternative. The subsequent discovery of large deposits in Brazil dramatically reduced the price of zircon, making it more accessible and solidifying its place in the modern birthstone chart.
Tanzanite is the newest of the three, a product of 20th-century discovery. Its addition to the December birthstone list was a significant event, marking the first change to the list in 50 years when it was officially added by the American Gem Trade Association. Unlike the ancient lineage of turquoise and the historical confusion of zircon, tanzanite’s story is one of modern exploration and rapid recognition. Its unique violet-blue color and pleochroic properties (displaying different colors from different angles) made it an instant sensation in the gem world. While it lacks the millennia-long history of the other two, its rapid ascent to birthstone status reflects the evolving nature of gemological tradition and the desire to offer contemporary options that resonate with modern tastes.
The evolution of the birthstone chart itself is a key part of this history. The first major update to the U.S. list occurred in 1952, adding alexandrite, citrine, and pink tourmaline. Further revisions included tanzanite for December and spinel for August. These changes illustrate a dynamic tradition that incorporates new discoveries and cultural shifts, ensuring the birthstone list remains relevant and diverse. For December, the current trio of turquoise, zircon, and tanzanite offers a range of colors and origins, allowing individuals to choose a stone that best fits their personal style while connecting to a rich historical narrative.
Geological Formation and Sources
Understanding the geological origins of these gemstones reveals why they are so distinct and where they are found. Each of the December birthstones forms under different conditions and is sourced from specific regions around the world.
Turquoise is a hydrous phosphate mineral, specifically an opaque, blue-to-greenish mineral that forms in arid regions where acidic water percolates through rocks containing aluminum and copper. This process, known as secondary mineralization, occurs in the near-surface environment. The color of turquoise, ranging from sky blue to greenish-yellow, is primarily determined by the presence of copper (blue) and iron (green). The most prized turquoise is a bright, even blue, often found in the Southwestern United States, a region with a long history of turquoise mining and use. The stone’s opacity means it is typically cut into cabochons, often in freeform shapes to maximize the use of the rough material, rather than being cut into calibrated shapes. While genuine turquoise is affordable for many, lab-created versions are also available for cost-conscious shoppers, though transparency about the stone’s origin is crucial for ethical sales.
Zircon is a zirconium silicate (ZrSiO₄) and is one of the oldest minerals on Earth, with crystals dating back billions of years. It forms in a variety of geological settings, including igneous, metamorphic, and sedimentary rocks. The most significant commercial sources for gem-quality zircon are found in Cambodia, Sri Lanka, and Thailand, though deposits also exist in Australia, Myanmar, and the United States. The large deposits in Brazil, mentioned in the context of its price reduction, have made zircon more accessible. Zircon’s high luster and refractive index give it a brilliant sparkle, and it can exhibit a colorful fire similar to diamond. However, it is important to note that zircon is distinct from cubic zirconia (CZ), a synthetic diamond simulant. Natural zircon is a valuable gemstone in its own right.
Tanzanite is the blue to violet variety of the mineral zoisite, with the chemical formula Ca₂Al₃(SiO₄)₃(OH). It is a relatively rare gemstone, found almost exclusively in a small area of the Merelani Hills of northern Tanzania, near the base of Mount Kilimanjaro. This geographic limitation makes tanzanite one of the most location-specific gemstones in the world. The stone forms through a complex metamorphic process involving heat and pressure from tectonic activity. Its discovery in 1967 led to its rapid commercialization, and its unique color—ranging from ultramarine to violet-blue—is a result of the presence of vanadium and other trace elements. The pleochroic nature of tanzanite means it can display different shades of blue, violet, and burgundy depending on the viewing angle, making expert cutting essential to maximize its color.
The global mining locations for these stones are diverse. Turquoise is mined in the United States (especially Arizona and New Mexico), Iran, and China. Zircon sources include Asia (Cambodia, Sri Lanka, Thailand) and Australia. Tanzanite is mined exclusively in Tanzania. This geographic distribution not only affects the availability and price of each stone but also adds to their mystique, as each stone carries the geological signature of its unique origin.
Gemological Properties
The physical and optical characteristics of a gemstone determine its durability, appearance, and value. The December birthstones exhibit a wide range of properties, from the soft, opaque turquoise to the brilliant, hard zircon and the pleochroic tanzanite.
Turquoise is an opaque mineral with a hardness of 5 to 6 on the Mohs scale, making it relatively soft and susceptible to scratching. Its specific gravity ranges from 2.60 to 2.90, and it has a refractive index of approximately 1.61 to 1.65. Due to its opacity and moderate hardness, turquoise is almost always cut as a cabochon, a smooth, rounded dome shape that protects the stone and enhances its color. It is also prone to cracking and discoloration if exposed to chemicals, heat, or prolonged sunlight, which can dry it out. This vulnerability means turquoise jewelry requires careful handling and cleaning with mild, soapy water and a soft cloth.
Zircon is a much harder gemstone, with a Mohs hardness of 6.5 to 7.5, making it suitable for all types of jewelry, including rings. It has a high refractive index (1.92 to 2.01) and strong dispersion (0.039), which gives it exceptional brilliance and fire, often compared to that of diamond. Zircon is also pleochroic, showing different colors when viewed from different crystal directions. However, zircon can be brittle due to its crystal structure and may be prone to breaking if struck. It is important to note that zircon is often heat-treated to enhance its color, particularly to transform brownish zircon into the more desirable blue variety, which is commonly used in December jewelry.
Tanzanite has a hardness of 6 to 7 on the Mohs scale, making it moderately durable but suitable for jewelry with care. It has a specific gravity of 3.35 and a refractive index of 1.69 to 1.70. Its most distinctive property is its strong trichroism, displaying three different colors: blue, violet, and burgundy. This characteristic requires skilled cutting to orient the stone for the most desirable blue-violet hue. Like zircon, tanzanite is often heat-treated to achieve its vivid blue color; untreated tanzanite is typically brownish. The stone is also susceptible to abrasion and should be protected from sharp blows.
The following table summarizes the key gemological properties of the December birthstones:
| Gemstone | Chemical Formula | Mohs Hardness | Specific Gravity | Refractive Index | Typical Cut | Key Properties |
|---|---|---|---|---|---|---|
| Turquoise | Hydrous phosphate (Cu,Al)₆(PO₄)₄(OH)₈·4H₂O | 5 - 6 | 2.60 - 2.90 | 1.61 - 1.65 | Cabochon | Opaque, prone to scratching and cracking, color from copper. |
| Zircon | ZrSiO₄ | 6.5 - 7.5 | 4.6 - 4.7 | 1.92 - 2.01 | Faceted | High luster and fire, pleochroic, often heat-treated for color. |
| Tanzanite | Ca₂Al₃(SiO₄)₃(OH) | 6 - 7 | 3.35 | 1.69 - 1.70 | Faceted | Strong trichroism (blue, violet, burgundy), often heat-treated. |
These properties directly influence the care, setting, and wearability of each stone. For example, the low hardness of turquoise means it is best set in protective settings for daily wear, while the higher hardness of zircon and tanzanite allows for more versatile use, though their brittleness still requires caution.
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, gemstones have been imbued with symbolic meanings and metaphysical powers for centuries. The December birthstones are no exception, each carrying a legacy of beliefs that range from ancient protective talismans to modern tokens of good fortune.
Turquoise has long been regarded as a stone of protection, healing, and wisdom. In many cultures, it was believed to ward off evil spirits and bring good fortune to the wearer. For the Native American tribes of the Southwest, turquoise is sacred, symbolizing the sky, water, and the earth’s spiritual connection. It is often used in ceremonial jewelry and is believed to promote balance, peace, and clarity of mind. In other traditions, turquoise is thought to have healing properties, particularly for the respiratory and immune systems. Today, it is often worn as a token of good luck and a reminder of one’s connection to nature and tradition.
Zircon, with its diamond-like appearance, has historically been associated with wisdom, honor, and purity. It was believed to promote prosperity and protect against harm. In some cultures, zircon was thought to aid in sleep and bring peace to the wearer. Its brilliant fire was seen as a symbol of spiritual light. While not as steeped in ancient lore as turquoise, zircon’s reputation as a gem of clarity and brilliance has made it a popular choice for those seeking a stone that represents focus and enlightenment.
Tanzanite, as a modern discovery, has quickly developed its own set of symbolic meanings. It is often associated with transformation, intuition, and spiritual awakening. Its unique color, which shifts between blue and violet, is seen as a metaphor for the journey of self-discovery and the opening of the mind to higher consciousness. Some believe tanzanite enhances communication and creativity, making it a stone for artists and thinkers. While its metaphysical beliefs are more contemporary, they reflect a desire to connect the stone’s unique properties to personal growth and modern spiritual practices.
In the broader context of birthstone symbolism, all three stones are considered tokens of good fortune for December-born individuals. The choice between them often comes down to personal preference—whether one is drawn to the ancient heritage of turquoise, the brilliant sparkle of zircon, or the transformative allure of tanzanite. It is important to note that while these symbolic meanings are valued by many, they are rooted in folklore and tradition rather than scientific evidence. Nonetheless, they add a layer of personal significance that enhances the emotional value of the gemstone.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of any gemstone. The December birthstones, with their differing properties, require specific maintenance routines to prevent damage and preserve their appearance.
Turquoise, due to its relative softness (Mohs 5-6) and porosity, is the most delicate of the three. It should be protected from scratches, chemicals, and extreme temperatures. To clean turquoise jewelry, use only mild, soapy water and a soft cloth. Avoid ultrasonic cleaners, steam cleaners, and harsh chemicals, as these can damage the stone’s surface and cause discoloration. It is also advisable to store turquoise separately from harder gemstones to prevent abrasion. When not in use, keep it in a soft pouch away from direct sunlight and heat, which can dry out the stone and lead to cracking.
Zircon, while harder (Mohs 6.5-7.5), is brittle and can be prone to breaking if struck. It is also sensitive to heat, which can cause it to fracture. Therefore, zircon should not be exposed to sudden temperature changes. Cleaning can be done with warm, soapy water and a soft brush, but ultrasonic cleaners should be used with caution, as vibrations may cause damage. Steam cleaning is not recommended. When setting zircon in jewelry, it is best to use protective settings like bezels to minimize the risk of impact.
Tanzanite has a hardness of 6 to 7, making it moderately durable but still susceptible to scratches and abrasions. Its cleavage is also a concern; it can break along certain planes if struck. Cleaning should be done gently with warm, soapy water and a soft brush. Avoid ultrasonic cleaners and steam, as these can cause internal fractures. Like zircon, tanzanite should be stored carefully to avoid contact with harder materials. Given its rarity and value, it is often recommended to remove tanzanite jewelry during activities that could subject it to physical stress.
In general, all three gemstones benefit from regular, gentle cleaning and proper storage. For any gemstone, it is wise to consult a professional jeweler for advice on specific care, especially for intricate settings or older pieces. By following these guidelines, owners of turquoise, zircon, and tanzanite jewelry can ensure that their birthstones remain vibrant and beautiful for generations.
Conclusion
The December birthstones—turquoise, zircon, and tanzanite—offer a fascinating triad of options that span millennia of history, from ancient talismans to modern marvels. Turquoise carries the weight of ancient cultures, particularly in the Southwestern United States, where its use dates back over two millennia. Zircon provides a brilliant, diamond-like alternative with a history of misidentification and recent accessibility due to Brazilian deposits. Tanzanite, the newest addition, represents the dynamic nature of gemology, with its exclusive origin in Tanzania and its rapid rise to birthstone status in 1952. Each stone possesses distinct gemological properties: turquoise’s soft, opaque beauty; zircon’s exceptional hardness and fire; and tanzanite’s captivating pleochroism. Their symbolic meanings—from protection and wisdom to transformation—add layers of personal significance. Ultimately, the choice among these three stones allows December-born individuals to connect with a rich tapestry of geological, historical, and cultural narratives, selecting a gemstone that not only adorns but also resonates with their personal story.