The final month of the year is uniquely endowed with a rich palette of birthstones, offering a diverse spectrum of color, history, and significance. December’s birthstones—Tanzanite, Turquoise, Zircon, and Lapis Lazuli—provide a captivating range from the vibrant blues and purples of modern discoveries to the ancient, sky-like hues of timeless classics. This variety ensures that those born in December have a wealth of choices, each stone carrying its own distinct story, from the icy fire of a colorless zircon to the deep, celestial blue of lapis lazuli.
This comprehensive guide delves into the gemological properties, historical lore, and cultural symbolism of December’s birthstones. It explores how these gems are formed and sourced, examines their unique physical characteristics, and provides essential advice for their care and preservation. By drawing upon established information from gemological sources, this article offers an authoritative resource for enthusiasts, collectors, and anyone seeking to understand the profound legacy of December’s gems.
The Modern Standard: Tanzanite
Tanzanite is the most prominent modern birthstone for December, a relative newcomer to the world of colored gems that has nonetheless achieved immense popularity. Its story is one of recent discovery and rapid ascent to prominence.
History and Discovery
Unlike gems known for millennia, Tanzanite’s history is remarkably brief. It was first discovered in the mid-20th century in a single, small area of Tanzania, which gives the stone its name. This exclusive geographic origin is a key part of its allure and value proposition. The gemstone is a variety of the mineral zoisite and owes its existence to a unique geological event that occurred around 585 million years ago, during the Precambrian era. An intense heating event, likely from a massive natural tectonic event, altered the brownish zoisite crystals into the vibrant blue and purple stones we know today.
The Tiffany & Co. jewelry company introduced Tanzanite to the world in 1968, marketing it heavily due to its exceptional color and limited availability. Its association with the "birthstone for December" was solidified by the American Gem Trade Association (AGTA) in 2002, making it a relatively recent but official addition to the modern birthstone list.
Gemological Properties
Tanzanite is celebrated for its remarkable pleochroism, the ability to display different colors when viewed from different crystal directions. A single cut Tanzanite can show a vibrant blue, a deep violet, and a reddish-purple hue simultaneously. This characteristic makes the orientation of the rough stone critical for lapidaries aiming to present the most desirable color face-up.
- Mineral: Zoisite
- Chemical Composition: Ca2Al3(SiO4)3O
- Hardness (Mohs Scale): 6.5 - 7
- Refractive Index: 1.690 - 1.700
- Crystal System: Orthorhombic
The most sought-after color for Tanzanite is a deep, saturated blue with violet undertones, often described as "violetish blue." Because most rough material is naturally a brownish color, virtually all Tanzanite on the market has been heat-treated to remove the brown component and induce the desirable blue and violet hues. This treatment is stable and permanent and is accepted as a standard industry practice.
Symbolism and Meaning
As a modern gem, Tanzanite’s symbolism is tied to its unique origin and color. It is often associated with a unique sense of style and sophistication. Metaphysically, it is credited with promoting a calm and meditative state, helping to bridge the gap between the conscious and spiritual selves. Its color, reminiscent of the sky at twilight, connects it to themes of transformation and new beginnings.
The Ancient Classic: Turquoise
Turquoise is arguably one of the oldest known gemstones, with a history of use and reverence that spans continents and millennia. Its distinctive robin's-egg blue has made it a cultural icon, deeply embedded in the traditions of ancient Egypt, Persia, and the Americas.
History and Lore
The name "turquoise" itself points to its origin, as it was first brought to Europe from the Middle East via Turkey, having been mined for centuries in the Persian province of Khorasan. Ancient Egyptians mined turquoise as early as 3,000 B.C., adorning royalty and sacred objects with the stone. The Persian turquoise was highly prized for its pure, sky-blue color, often containing a fine, spiderweb-like matrix of dark host rock. For the ancient Persians, it symbolized protection and good fortune, a belief that has persisted through the ages. Similarly, many Native American cultures, particularly the Navajo, Zuni, and Pueblo peoples, hold turquoise as a sacred stone, representing the sky and water and using it in intricate inlay and jewelry work.
Gemological Properties
Turquoise is an opaque mineral, a hydrated phosphate of copper and aluminum. Its color is directly linked to its chemical composition; the presence of copper yields the blue hues, while iron contributes to greenish tones.
- Mineral: Turquoise
- Chemical Composition: CuAl6(PO4)4(OH)8·4H2O
- Hardness (Mohs Scale): 5 - 6
- Refractive Index: 1.610 - 1.650
- Crystal System: Triclinic
Turquoise is rarely found without some form of surface alteration or "matrix" from the host rock. The quality of turquoise is judged by its color, hardness, and the pattern of its matrix. High-quality, "sleeping" turquoise with a smooth, waxy luster is highly valued. Due to its porosity and relative softness, turquoise is often stabilized with wax or resin to enhance its durability and color.
Symbolism and Meaning
Turquoise is universally regarded as a stone of protection, healing, and good fortune. It was historically worn by warriors and travelers to ward off injury and bad luck. Its connection to the sky and water imbues it with a sense of tranquility and peace. In many cultures, it is a symbol of wisdom and communication, believed to align all the chakras and provide a sense of balance and serenity to the wearer.
The Fire-Bearing Gem: Zircon
Zircon is a gem whose name is often confused with the synthetic cubic zirconia, a common diamond simulant. This confusion does a great disservice to natural zircon, one of the oldest minerals on Earth and a gem of exceptional brilliance and fire.
History and Discovery
Zircon has been used in jewelry for centuries. Its name is derived from the Persian word zargun, meaning "gold-colored," a testament to the variety of hues this mineral can display. While today it is most famous for its colorless form, which rivals diamond in its dispersion ("fire"), zircon has a long history as a brownish gem that was heat-treated to achieve a blue color. In the Middle Ages, it was believed to promote honor, wisdom, and wealth. Its status as a December birthstone is long-standing, representing the traditional option for the month.
Gemological Properties
Zircon is the birthstone for December that boasts the highest refractive index and dispersion of any natural gemstone, giving it a spectacular brilliance and fire that is immediately noticeable. It is a heavy stone for its size, a property known as high specific gravity.
- Mineral: Zircon
- Chemical Composition: ZrSiO4
- Hardness (Mohs Scale): 6.5 - 7.5
- Refractive Index: 1.920 - 2.010
- Dispersion: 0.039 (High)
- Crystal System: Tetragonal
Colorless zircon is a celebrated diamond alternative, but it is more brittle and prone to chipping than diamond, requiring careful setting. Blue zircon, typically achieved through heat treatment of brown zircon, is a popular December birthstone. Other colors include green, yellow, and red (known as hyacinth). Its hardness makes it suitable for most jewelry, though care must be taken to avoid sharp blows.
Symbolism and Meaning
Zircon has long been associated with wisdom, honor, and riches. It is believed to help its wearer achieve their goals and promote spiritual growth. The colorless variety is associated with purity and clarity of thought, while the blue zircon is linked to tranquility and peace. Its fiery brilliance is seen as a symbol of passion and energy.
The Celestial Stone: Lapis Lazuli
Lapis Lazuli is not a single mineral but a metamorphic rock composed of multiple minerals, primarily the blue silicate lazurite, along with calcite and pyrite. Its intense, ultramarine blue has captivated humanity since antiquity.
History and Lore
The history of Lapis Lazuli is as deep as its color. It was one of the most prized stones in ancient Egypt, used for jewelry, amulets, and the famous eye makeup of Cleopatra. The Sumerians believed it contained the spirits of their gods. Its most significant historical role, however, was as a pigment. For centuries, ground Lapis Lazuli was the only source for the pigment ultramarine, the most expensive and prized blue used by Renaissance painters to depict the robes of the Virgin Mary. Its association with the heavens and divinity is a recurring theme across many cultures.
Gemological Properties
As a rock, Lapis Lazuli’s properties are an aggregate of its constituent minerals. Its value is determined by the intensity and uniformity of its blue color, with the most prized specimens being a deep, even azure with minimal calcite (white veins) and a dusting of golden pyrite flecks, which are considered a desirable feature.
- Composition: Primarily Lazurite, with Calcite and Pyrite
- Hardness (Mohs Scale): 5 - 5.5 (as a rock, varies by mineral component)
- Refractive Index: ~1.50 (average)
- Crystal System: Isometric (for lazurite)
Lapis Lazuli is relatively soft and porous, making it susceptible to damage from chemicals, heat, and pressure. It is often polished into cabochons, beads, or carved objects rather than faceted.
Symbolism and Meaning
Lapis Lazuli is a stone of wisdom, truth, and inner power. Its connection to the heavens has made it a symbol of universal truth and cosmic awareness. It is believed to enhance intellectual ability and stimulate the higher mind, promoting clarity and objectivity. Historically, it was a stone of royalty and priests, representing power, vision, and spiritual enlightenment.
Birthstone History and Standardization
The concept of wearing a specific gemstone corresponding to one's birth month has evolved over centuries. The modern list is largely derived from the Breastplate of Aaron, a religious garment described in the Book of Exodus, which was set with twelve stones representing the twelve tribes of Israel. These stones later became associated with zodiac signs and eventually, calendar months.
The first official standardization in the United States was established by the National Association of Jewelers (now Jewelers of America) in 1912. This list has been periodically updated to reflect market availability and consumer trends. The addition of Tanzanite in 2002 is a prime example of this evolution. The American Gem Trade Association (AGTA) has also played a key role in these updates, adding stones like tanzanite and spinel. This process ensures the birthstone list remains relevant while honoring tradition. For December, this has resulted in a diverse selection that includes both the modern choice (Tanzanite) and traditional options (Zircon, Turquoise, and Lapis Lazuli).
Caring for Your December Gems
Proper care is essential to maintain the beauty and longevity of gemstone jewelry. Due to their varying hardness and stability, December’s birthstones require specific handling.
- Tanzanite (Hardness 6.5-7): This gem is moderately durable but can be susceptible to chipping due to its cleavage. It is best cleaned with warm, soapy water and a soft brush. Avoid ultrasonic and steam cleaners, as the heat and vibrations can cause damage.
- Turquoise (Hardness 5-6): As a porous stone, turquoise is sensitive to chemicals, including cosmetics, lotions, and even skin oils, which can cause discoloration over time. Clean it gently with a soft, damp cloth. Avoid chemical cleaners and prolonged exposure to direct sunlight or heat.
- Zircon (Hardness 6.5-7.5): While harder than turquoise, zircon is brittle and can be damaged by sharp blows. It is generally safe to clean with warm, soapy water and a soft brush. Avoid ultrasonic cleaners, which can exacerbate any existing fractures.
- Lapis Lazuli (Hardness 5-5.5): This is the softest and most delicate of the December stones. It can be easily scratched and damaged by acids and heat. Clean only with a soft, dry cloth. If necessary, use a damp cloth with a tiny amount of mild soap, and dry immediately. Avoid all chemical cleaners, ultrasonics, and steam.
Conclusion
The birthstones of December offer an unparalleled journey through the worlds of geology, history, and human culture. From the recent discovery of Tanzanite in the foothills of Mount Kilimanjaro to the ancient quarries that yielded Turquoise for pharaohs and Lapis Lazuli for Renaissance masters, these gems carry the weight of time and the spark of the Earth’s creative power. Zircon, with its ancient origins and diamond-like fire, adds a touch of brilliant tradition to the month’s offerings.
Together, these four stones provide a complete spectrum of color, durability, and meaning, allowing anyone born in the final month of the year to choose a gem that resonates with their personal style and story. Whether one is drawn to the protective lore of turquoise, the celestial wisdom of lapis lazuli, the fiery brilliance of zircon, or the transformative beauty of tanzanite, December’s gems are a testament to the enduring fascination and remarkable diversity of the mineral kingdom.