December stands unique in the calendar of birthstones, offering not one, but three distinct gemstones to those born in the final month of the year: turquoise, zircon, and tanzanite. This multiplicity is not an anomaly but a reflection of the evolving nature of birthstone traditions, shaped by centuries of cultural practice, commercial influence, and geological discovery. Each of these gemstones carries its own distinct history, set of gemological properties, and body of symbolic meaning, making December a particularly rich and fascinating subject within the world of gemology. While the concept of birthstones dates back to Biblical times, the list has evolved significantly, especially in the 20th and 21st centuries. This article provides a comprehensive exploration of these three December birthstones, detailing their historical journey, geological origins, scientific characteristics, and the cultural lore that has cemented their place as symbols of the winter month.
Historical and Cultural Significance
The tradition of associating specific gemstones with birth months is believed to have originated in the Biblical Book of Exodus. The text describes Aaron’s breastplate, adorned with twelve stones representing the twelve tribes of Israel. Over centuries, these stones were gradually associated with the months of the year, a tradition adopted and adapted by various cultures. For December, the earliest historical references point to ruby as its birthstone. However, the list has undergone considerable transformation, particularly since the 19th century.
The modern list of December birthstones has seen several key changes, documented by industry authorities. In 1870, turquoise was designated as a December birthstone in a pamphlet published by Tiffany & Co. titled Gregorian Birthstone Poems. This commercial influence marked a significant step in formalizing birthstone traditions. By 1912, the National Association of Jewellers (now the Jewellers of America) had established a standardized list, naming turquoise as the primary December birthstone and lapis lazuli as an alternative. This list continued to evolve; in 1952, the Jewelry Industry Council of America added zircon to the list, replacing lapis lazuli. The most recent addition came in 2002, when the American Gem Trade Association (AGTA) officially recognized tanzanite as a December birthstone. This fluidity in the list reflects the dynamic nature of gemstone popularity and the influence of commercial and cultural trends on birthstone traditions.
Each of the three gemstones has a deep and storied history that predates its formal designation as a birthstone. Turquoise is one of the oldest known gemstones, with evidence of its use dating back to 5,000 BCE in Egypt, where it was used in jewelry and amulets. In ancient Egypt, turquoise was associated with the gods and was believed to offer divine protection. The pharaohs wore it to signify power and connection to the heavens. In China, turquoise was carved into intricate objects and used in ceremonies. Its use spread across the globe, from the Persian Empire, where it was a treasured gem, to the Americas, where it became a cornerstone of Native American art and spirituality.
Zircon is also an ancient gemstone. While often confused with cubic zirconia, a synthetic diamond simulant, natural zircon is one of the oldest minerals on Earth, with crystals found in Australia that are over 4.4 billion years old. Historically, blue zircon was particularly popular during the Victorian era, often used in fine jewelry. Its brilliance and fire made it a desirable alternative to diamonds.
Tanzanite, in contrast, is a relatively modern discovery. It was first found in the Merelani Hills of Tanzania in 1967. Its stunning violet-blue color and pleochroism (showing different colors from different angles) quickly captured the attention of the gemological world. The gemstone was initially marketed by Tiffany & Co., which named it after its country of origin. Its official addition to the December birthstone list in 2002 solidified its status as a modern classic, offering a contemporary alternative to the ancient stones of turquoise and zircon.
Turquoise: The Ancient Protector
Turquoise is the oldest and most traditional December birthstone, treasured for thousands of years. This gemstone is a phosphate mineral that is typically semi-transparent or opaque, with colors ranging from sky blue to green. The specific hue is determined by the presence of copper (which creates blue) and iron (which creates green). Many turquoise stones display dark veining known as “matrix,” which is the remnant of the host rock in which the turquoise formed. Highly prized varieties feature a vibrant, even color with minimal matrix.
Several specific varieties of turquoise are renowned for their quality and appearance. Persian turquoise is the most prized variety, celebrated for its vivid, evenly saturated sky-blue color and its characteristically minimal to nonexistent matrix. Sourced historically from Iran’s ancient mines, this premium turquoise has been admired for centuries for its purity, durability, and remarkable hue. Its clean, uninterrupted color makes it highly sought after for fine jewelry and collector-grade pieces.
Another famous variety is Sleeping Beauty Turquoise, renowned for its pure, robin’s-egg blue color and its exceptionally low to absent matrix. Mined exclusively from the Sleeping Beauty Mine in Arizona before its closure, this turquoise is treasured for its smooth, uniform appearance and vibrant hue. The mine’s closure has made stones from this source increasingly rare and valuable.
The color of turquoise is a subject of great appreciation. It occurs in a range of colors: from various shades of green to greenish-yellow to the more recognizable robin egg blue and sky blue. The gem is semi-translucent to opaque and can be found with veins or spiderwebs, which occur due to the presence of a host of different elements. The veins can appear brown or black. It can be waxy to the touch and glassy or dull in appearance. The gem’s unique color and texture have made it a favorite across cultures.
Turquoise has held significant meaning for Native American tribes, particularly in the Southwestern United States. For these cultures, turquoise is not merely a decorative stone but a living entity, a piece of the sky that fell to Earth. It is used in intricate jewelry, ceremonial objects, and as a talisman for protection and healing. The stone’s connection to water and the sky makes it a powerful symbol of life and renewal in arid landscapes.
Zircon: The Brilliant Ancient
Zircon is a naturally occurring mineral composed of zirconium silicate (ZrSiO₄). It is one of the hardest gemstones, with a Mohs hardness of 7.5, making it relatively durable for jewelry. While zircon occurs in a variety of colors, including green, yellow, brown, and red, the blue variety is most closely associated with December. Blue zircon is typically heat-treated to achieve its vibrant color; heat treatment is a standard and widely accepted practice in the gem trade.
The gemological properties of zircon are notable for their brilliance. It has a high refractive index, which gives it exceptional sparkle and fire, often compared to that of a diamond. Its dispersion (the ability to split light into spectral colors) is also high, contributing to its lively appearance. Zircon is also pleochroic, meaning it can show different colors when viewed from different crystal directions, though this is less pronounced than in tanzanite.
Historically, blue zircon was a popular gemstone during the Victorian era, often set in intricate gold jewelry. Its brilliance and relative affordability made it an attractive alternative to more expensive blue gems like sapphire. The gem’s ancient origins add to its allure; as mentioned, some zircon crystals are billions of years old, making them some of the oldest material on Earth.
In terms of symbolism, zircon is associated with clarity, wisdom, and a sense of balance. It is believed to sharpen focus and boost mental clarity. This association with clear thinking and wisdom aligns well with its brilliant, transparent appearance. For those born in December, zircon represents not only the icy blues of winter but also the clarity and insight that come with the end of the year.
Tanzanite: The Modern Marvel
Tanzanite is the newest member of the December birthstone family, yet it has quickly become one of the most sought-after gemstones of the modern era. Discovered in a single location in the world—the Merelani Hills of Northern Tanzania—tanzanite is a variety of the mineral zoisite. Its signature feature is its intense violet-blue color, which is the result of trace amounts of vanadium within its crystal structure. The color can range from a pale lavender to a deep, saturated blue-violet, and it is often enhanced by heat treatment to stabilize the color and remove undesirable brownish hues.
One of the most captivating properties of tanzanite is its strong pleochroism. When viewed from different angles, the stone can display three distinct colors: blue, violet, and burgundy-red. This dynamic color play makes tanzanite exceptionally lively and engaging in jewelry. However, this same property requires careful cutting to ensure the stone shows its best face-forward color. The gem has a Mohs hardness of 6.5 to 7, which makes it somewhat softer than zircon or sapphire, requiring careful handling to avoid scratches and impacts.
The discovery of tanzanite in 1967 revolutionized the gemstone market. Its unique color and rarity—found only in one small area of Tanzania—made it an instant sensation. Tiffany & Co. recognized its potential early on and launched a major marketing campaign, naming it after its country of origin and promoting it as the “gemstone of a generation.” This strategic move helped establish tanzanite as a desirable and fashionable gemstone.
In 2002, the American Gem Trade Association (AGTA) officially recognized tanzanite as a birthstone for December, a testament to its rapid rise in popularity and cultural significance. Symbolically, tanzanite represents transformation, new beginnings, and spiritual awakening. Its blue-violet hue is often associated with intuition and higher consciousness, making it a meaningful choice for those seeking personal growth and change.
Gemological Properties
Understanding the physical and chemical properties of these gemstones is essential for appreciating their value and care. The following table summarizes the key gemological characteristics of turquoise, zircon, and tanzanite based on the provided sources.
| Property | Turquoise | Zircon (Blue) | Tanzanite |
|---|---|---|---|
| Mineral Family | Phosphate | Zirconium Silicate | Zoisite (Variety) |
| Chemical Formula | CuAl₆(PO₄)₄(OH)₈·4H₂O | ZrSiO₄ | Ca₂Al₃(SiO₄)₃(OH) |
| Mohs Hardness | 5 - 6 | 7.5 | 6.5 - 7 |
| Crystal System | Triclinic | Tetragonal | Orthorhombic |
| Refractive Index | 1.61 - 1.65 | 1.92 - 2.01 | 1.69 - 1.70 |
| Specific Gravity | 2.6 - 2.9 | 4.6 - 4.7 | 3.35 |
| Color Range | Sky blue to green, often with matrix | Blue (often heat-treated) | Violet-blue to blue-violet |
| Transparency | Opaque to semi-transparent | Transparent to translucent | Transparent to translucent |
| Pleochroism | None | Weak | Strong (Blue, Violet, Red) |
| Primary Sources | Iran, USA (Arizona, Nevada), China, Afghanistan | Australia, Cambodia, Myanmar, Tanzania | Tanzania (Merelani Hills) |
Turquoise is a relatively soft and porous stone. Its hardness of 5-6 on the Mohs scale makes it susceptible to scratches and damage from chemicals. It is often treated or stabilized with resins to enhance its durability and color. The presence of matrix (host rock) is a natural characteristic and can affect value; stones with even, vibrant color and minimal matrix are most prized.
Zircon is one of the hardest gemstones in this group, with a Mohs hardness of 7.5. This makes it durable for everyday wear, though it can be brittle and prone to chipping if struck hard. Its high refractive index and dispersion give it exceptional brilliance. Most blue zircon on the market has been heat-treated to achieve its color, a stable and permanent process.
Tanzanite has a Mohs hardness of 6.5 to 7, placing it in the moderate range for gemstone durability. It is more susceptible to scratches than zircon and can be damaged by sharp blows. Its strong pleochroism requires skilled cutting to maximize its beauty. Like zircon, tanzanite is often heat-treated to enhance its color, and this treatment is considered standard and acceptable in the gem trade.
Symbolism and Metaphysical Beliefs
Beyond their physical properties, these gemstones are rich in symbolism and metaphysical lore, which has been passed down through generations.
Turquoise is universally regarded as a stone of protection, healing, and good fortune. In ancient Egypt, it was believed to offer divine protection and was used in amulets and jewelry for the pharaohs. In Persian culture, turquoise was thought to bring protection from unnatural death and to ensure the wearer’s safety. A notable belief, dating back to the 13th century, was that turquoise would protect the wearer from falling, leading to its use on horse bridles. There was also a belief that the gem would break into multiple pieces when disaster was imminent, acting as a warning system. For Native American tribes, turquoise is a sacred stone that connects the wearer to the sky and water, promoting peace, happiness, and spiritual grounding. Hindu mystics believed that seeing a turquoise after observing a New Moon would bring wealth. The stone has long been thought to possess the powers to ensure good health and fortune, promote happiness, peace, positive energy, protection, and spirituality.
Zircon is associated with clarity, wisdom, and mental focus. It is believed to sharpen the mind, enhance concentration, and promote a sense of balance and stability. In some traditions, zircon is thought to aid in spiritual growth and to help the wearer connect with their higher self. Its brilliant, clear appearance is often linked to the clarity of thought and purpose.
Tanzanite, as a modern gemstone, carries symbolism related to transformation and new beginnings. Its discovery in the 20th century and its rapid rise to fame mirror themes of change and evolution. It is often linked to intuition, spiritual awakening, and the pursuit of one’s destiny. The gem’s captivating color shift is seen as a metaphor for seeing the world from different perspectives and embracing change. It represents stepping into something new with clarity and curiosity.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of these gemstones, and their care requirements differ based on their physical properties.
Turquoise is the most delicate of the three. Due to its porosity and relatively low hardness, it is susceptible to damage from chemicals, heat, and prolonged exposure to sunlight, which can cause fading. It should be cleaned with a soft, damp cloth and mild soap. Avoid ultrasonic cleaners, steam cleaners, and harsh chemicals. It is best to remove turquoise jewelry before engaging in activities that could cause impact or exposure to lotions, perfumes, or cleaning agents. To prevent scratching, store turquoise separately from other jewelry.
Zircon, with its higher hardness, is more durable but can be brittle. It is relatively safe for everyday wear but should be protected from sharp blows. Cleaning zircon is straightforward; it can be washed with warm, soapy water and a soft brush. Ultrasonic cleaners are generally safe for untreated zircon, but caution is advised for stones that have been fracture-filled (though this is less common for blue zircon). It is best to avoid sudden temperature changes, which could cause thermal shock.
Tanzanite requires careful handling due to its moderate hardness and perfect cleavage in one direction, which makes it vulnerable to chipping or splitting if struck. It should never be exposed to ultrasonic cleaners or steam, as this can cause irreparable damage. Cleaning should be done with a soft brush, lukewarm water, and a mild detergent. It is advisable to remove tanzanite jewelry during physical activities, housework, or when applying cosmetics. When not in use, store tanzanite separately in a soft cloth or lined jewelry box to prevent scratches.
Conclusion
December’s birthstones—turquoise, zircon, and tanzanite—offer a remarkable trio that spans millennia of human history and geological time. From the ancient, protective talisman of turquoise to the brilliant, ancient clarity of zircon and the transformative, modern allure of tanzanite, each stone provides a unique narrative. Their journey from ancient artifacts and royal adornments to modern birthstones reflects the evolving relationship between humanity and the mineral world. Whether one is drawn to the historic depth of turquoise, the sparkling brilliance of zircon, or the vibrant, shifting colors of tanzanite, each gemstone carries a legacy of cultural significance, scientific fascination, and personal meaning. For those born in December, these stones are not just beautiful gems but symbols of protection, wisdom, and transformation, perfectly mirroring the reflective and celebratory spirit of the year’s final month.