For those born in the final month of the year, the question of a birthstone is uniquely expansive. Unlike most months, which are traditionally linked to a single gem, December boasts a diverse quartet of blue-hued stones: turquoise, zircon, tanzanite, and blue topaz. This variety offers a remarkable range of colors, histories, and properties, allowing for a deeply personal choice. Each gem carries its own narrative, from ancient amulets of protection to modern marvels of geological rarity. This article provides a comprehensive exploration of these four December birthstones, detailing their historical significance, geological origins, gemological properties, and cultural symbolism, drawing exclusively from authoritative sources to guide gemstone enthusiasts, jewelry buyers, and students of gemology.
Historical Evolution and Lore
The association of specific gems with specific months is a practice that has evolved over centuries. The modern list of birthstones is largely rooted in historical and religious traditions, most notably the breastplate of Aaron described in the Old Testament, which featured twelve stones representing the tribes of Israel. Over time, these lists were adapted and formalized. In 1912, the National Association of Jewelers in the United States standardized an unofficial list, blending historical customs with gemstones practical for commercial jewelry. This list has been updated several times, with the most significant changes for December occurring in 1952, when zircon was added, and in 2002, when tanzanite was included. The expansion to four stones is unique to December; some sources suggest this was to provide consumers with a wider variety of colors and more affordable options, reflecting both new gemstone discoveries and commercial offerings.
Turquoise: The Ancient Protector
Turquoise is arguably the most ancient of the December birthstones, with a history spanning millennia. Its name derives from the French pierre turquoise, meaning "Turkish stone," as it was brought to Europe through the gem markets of Constantinople. Historically, turquoise was mined in Persia and along the Sinai Peninsula. This gem has been a favorite of royalty and cultures worldwide, from ancient Egypt, where it was used in King Tut's funerary mask, to the Tibetan Plateau and the American Southwest. Native Americans of the Southwest associated the stone with youth and strength, while Incas and Mayas offered it as a gift to their gods. Turquoise was prized as an amulet, believed to protect its wearer from harm, including falls and negative energy. It was also thought to warn of impending illness or danger by changing color. In Tibet, turquoise was considered a stone of fortune and health, so valuable it was used as currency. For lovers and married couples, it was believed to protect relationships and preserve friendship when gifted.
Zircon: The Stone of Clarity
Zircon's history is also long and distinguished. It is one of the oldest minerals on Earth, with some zircon crystals dating back billions of years. However, its specific role as a December birthstone is more modern. It was officially added to the American birthstone list in 1952 by the Jewelry Industry Council of America. Historically, zircon has been confused with other stones, most notably cubic zirconia, a synthetic material, but natural zircon is a distinct and valuable gem. It is associated with wisdom, mental clarity, and a sense of balance. While its blue variety is the standard for December, zircon occurs in a range of colors.
Tanzanite: The Modern Marvel
Tanzanite is the youngest of the four, a product of modern discovery. It was first found in the Merelani Hills of Tanzania in 1967, making it a 20th-century addition to the gem world. Its status as a December birthstone was cemented in 2002 when it was officially added to the modern list. Its rapid rise to prominence is a testament to its unique beauty and rarity. It is associated with transformation, growth, and new beginnings, symbolizing a fresh chapter with clarity and curiosity. Its discovery is a recent chapter in gemological history, yet it has quickly become one of the most sought-after blue gems.
Blue Topaz: The Durable Blue
Blue topaz has a more ambiguous historical origin, with evidence of its use found throughout history, but its exact historical origin is unknown. Its popularity as a December birthstone is a more recent phenomenon. It gained significant traction in modern times due to its attractive blue color, relative affordability, and excellent durability. While not always included in the most traditional lists, it has become a mainstream December birthstone for many consumers, offering a crisp, winter blue color. It is the official state gem of Texas, highlighting its cultural significance in the United States.
Geological Formation and Global Sources
Each of these four gems forms under distinct geological conditions, leading to their unique appearances and sourcing patterns.
Turquoise is a hydrous phosphate of copper and aluminum that forms in arid regions where acidic, copper-rich groundwater seeps into and reacts with pre-existing minerals containing aluminum and phosphorus. The process is slow, and the resulting material often contains a matrix (host rock) that can create distinctive patterns. Significant sources include the southwestern United States (Arizona, New Mexico, Nevada), Iran, Egypt, China, Mexico, and parts of Central Asia and Africa.
Zircon is a zirconium silicate that forms in igneous and metamorphic rocks. It is a common mineral in many rock types, but gem-quality crystals are rarer. It is mined in various locations worldwide, including Sri Lanka, Brazil, Nigeria, and the United States.
Tanzanite is a variety of the mineral zoisite, colored by vanadium. It is found in only one known location on Earth: the Merelani Hills of Tanzania, near Mount Kilimanjaro. This extreme geographic rarity is the primary reason for its high value and cost.
Blue topaz is a silicate mineral containing aluminum and fluorine. While topaz crystals are found in many locations, the intense blue color seen in commercial gemstones is almost always the result of irradiation and heat treatment of colorless or pale yellow topaz. Natural blue topaz is exceptionally rare. Major sources for the raw material include Sri Lanka, Brazil, Mexico, Nigeria, and the United States.
Gemological Properties
The four December birthstones vary significantly in their physical properties, which directly impact their durability, care, and suitability for different types of jewelry. The following table summarizes key gemological characteristics based on the provided sources.
| Gemstone | Chemical Composition | Mohs Hardness | Key Properties & Notes |
|---|---|---|---|
| Turquoise | Hydrous copper aluminum phosphate (CuAl₆(PO₄)₄(OH)₈·4H₂O) | 5 - 6 | Relatively soft and porous. Often exhibits a matrix pattern. Color ranges from soft sky blue to greenish hues. |
| Zircon | Zirconium silicate (ZrSiO₄) | Not specified in sources | Typically appears bright, clear blue. Known for its clarity and sparkle. |
| Tanzanite | Calcium aluminum hydroxyl silicate (Ca₂Al₃(SiO₄)₃(OH)) | Not specified in sources | Rich violet-blue that can shift in color depending on the light (pleochroism). Fragile. |
| Blue Topaz | Aluminum fluorine hydroxyl silicate (Al₂SiO₄(F,OH)₂) | 8 | The hardest of the December birthstones, making it the most durable for everyday wear. |
Color and Appearance: All four stones share a blue color palette, but the shades vary dramatically. Turquoise ranges from soft sky blue to greenish hues, often with a distinctive matrix. Zircon typically presents as a bright, clear blue. Tanzanite offers a unique rich violet-blue with a captivating color shift. Blue topaz provides a crisp, often intense, winter blue.
Durability and Wearability: For jewelry intended for daily wear, hardness is a critical factor. Blue topaz, with a Mohs hardness of 8, is the most durable of the four, resistant to scratching and suitable for rings and bracelets that see frequent use. Turquoise, at 5-6 on the Mohs scale, is the softest and most delicate. It is more prone to scratching and damage from chemicals, oils, and impacts, making it better suited for pendants or earrings. Zircon and tanzanite are not assigned a hardness in the provided sources but are described as more durable than turquoise yet still fragile, requiring careful handling. Zircon is noted as being "a bit more durable while still sparkling," and tanzanite is explicitly called "fragile."
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, these stones are deeply imbued with meaning, which has contributed to their enduring popularity.
- Turquoise is universally seen as a stone of protection, grounding, and calm. It is believed to offer good fortune, wisdom, tranquility, and friendship. Its historical use as an amulet against falls and negative energy underscores its role as a guardian stone. It is also associated with preserving relationships and warning of illness.
- Zircon is linked to mental clarity, focus, and balance. It is believed to sharpen the mind and promote wisdom, making it a stone for those seeking intellectual or spiritual equilibrium.
- Tanzanite symbolizes transformation, new beginnings, and growth. Its color, which shifts between blue and violet, is thought to reflect the journey of stepping into a new chapter of life with clarity and curiosity.
- Blue Topaz, while less steeped in ancient lore than the others, is associated with calm, communication, and emotional balance, aligning with its serene blue color.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of December birthstone jewelry, and recommendations are dictated by each stone's specific properties.
- Turquoise: Due to its softness and porosity, turquoise requires the most care. It should be cleaned only with a soft, dry cloth. Avoid ultrasonic cleaners, steam cleaners, and chemical exposure (including perfumes, lotions, and cleaning agents), as these can damage the stone and its surface. Store it separately to prevent scratching.
- Zircon and Tanzanite: While more durable than turquoise, these stones are still relatively fragile. They can be cleaned with warm water, a mild detergent, and a soft brush. It is advisable to avoid ultrasonic cleaners and extreme temperature changes, which could cause fractures. Store them carefully to avoid impact damage.
- Blue Topaz: As the hardest of the group, blue topaz is more resilient. It can be cleaned with warm soapy water and a soft brush. Ultrasonic cleaners are generally safe, but steam cleaning is not recommended due to potential thermal shock. As with all gems, avoid harsh chemicals and sudden temperature changes.
Conclusion
December offers a unique and beautiful selection of birthstones, each with a distinct identity. Turquoise provides a connection to ancient history and protective symbolism, though it demands careful handling. Zircon offers brilliant clarity and mental balance. Tanzanite, a modern rarity, captivates with its color-shifting beauty and association with transformation. Blue topaz delivers exceptional durability and a classic, crisp blue hue. The choice among them allows for personal expression based on color preference, budget, lifestyle, and the symbolic meaning that resonates most deeply. Together, these four gems form a treasury of blue, perfectly mirroring the cool, reflective light of the winter month they represent.