For those born in the final month of the year, the birthstone selection is uniquely abundant. Unlike most months, which are traditionally associated with a single gem, December boasts a quartet of celebrated stones: Turquoise, Zircon, Tanzanite, and Blue Topaz. This variety offers a remarkable spectrum of blue hues, from the soft, sky-like tones of turquoise to the deep, shifting violet-blues of tanzanite. The expansion of the December birthstone list is a modern phenomenon, driven by both historical tradition and commercial evolution, providing December-born individuals with a range of choices based on color, durability, and personal significance. This article explores the history, geology, gemological properties, and symbolism of these four distinct blue gemstones, delving into the lore that has made them cherished for millennia and the practical considerations that make them suitable for contemporary jewelry.
History and Lore
The historical journey of December’s birthstones is a fascinating blend of ancient tradition and modern adaptation. The concept of birthstones itself has deep roots, often traced back to the biblical description of Aaron’s breastplate in the Book of Exodus, which featured twelve gemstones representing the twelve tribes of Israel. Later interpretations linked these stones to the twelve months of the year and the twelve signs of the zodiac, creating the foundation for the modern birthstone list. The first standardized list of birthstones by month was published in 1912 by the National Association of Jewelers in the United States, which combined longstanding customs with gemstones deemed practical for the jewelry trade. This list has been updated several times, most notably in 1952, when the Jewelry Industry Council of America added zircon to December’s list, and again in 2002, when tanzanite was officially included.
Turquoise is arguably the oldest of the December stones with a continuous history of use. Its name derives from the French pierre turquoise, meaning "Turkish stone," as it was brought to Europe from the gem markets of Constantinople (modern-day Istanbul), though its origins lay further east. Historical sources indicate turquoise was mined in Persia (modern-day Iran) and along the Sinai Peninsula. From the earliest times, it was a favored gem for amulets and talismans. Its relative softness made it easy to cut into various shapes and inscribe with protective symbols. In ancient Tibet, turquoise was so valued that it was used as a currency and was considered a birthstone of fortune, health, and success. For the Incas and Mayas, it was a sacred offering to their gods. Among Native American tribes of the American Southwest, turquoise is deeply embedded in culture, associated with youth, strength, and the sky and water deities. Its lore as a protective stone is widespread; it was believed to warn its wearer of impending illness or danger by changing color, typically becoming pale. It was also prized by lovers and married couples as a stone that could preserve friendship and protect relationships.
Zircon’s history is equally rich, though its identity has sometimes been confused with the synthetic cubic zirconia. The gemstone zircon is one of the oldest minerals on Earth, with zircon crystals found in Australia dating back over 4.4 billion years. For centuries, it has been appreciated for its high refractive index and brilliance, which can rival that of diamond. In the Middle Ages, it was believed to bring prosperity and honor to its wearer and to aid in sleep. Blue zircon, specifically, became a popular alternative to diamond in the Victorian era. Its inclusion in the modern birthstone list in 1952 solidified its place as a traditional December stone.
Tanzanite is the newest addition, a gem of modern discovery. It was identified in 1967 in the Merelani Hills of Tanzania, East Africa. Its rapid rise to prominence was due to its captivating violet-blue color and the marketing efforts of the jewelry company Tiffany & Co., which introduced it to the world in 1968 and named it after its country of origin. Recognizing its unique beauty and growing popularity, the Jewelry Industry Council of America added tanzanite to the official birthstone list in 2002, making it the most recent addition to the December family.
Blue Topaz has a more ambiguous historical origin. Unlike its cousin, the yellow topaz, which has been known since antiquity, the historical use of blue topaz is less clearly documented. However, it has become a staple of modern jewelry. Its widespread availability and durable nature have made it a popular choice for December-born individuals seeking a blue gemstone. The state of Texas designated blue topaz as its official state gem, further cementing its cultural significance in the United States.
Geological Formation and Sources
The four December birthstones originate from vastly different geological processes and are mined in distinct regions of the world, contributing to their rarity and value.
Turquoise is a secondary mineral formed in the near-surface environment where water carrying dissolved copper, aluminum, and phosphorus reacts with pre-existing rocks. This process occurs in arid regions, which is why its most significant deposits are found in dry climates. Key historical and modern sources include Iran (formerly Persia), the Sinai Peninsula, and the American Southwest (Arizona, New Mexico, and Nevada). The material from these regions can vary in color and matrix (the host rock embedded within the stone), with Persian turquoise often prized for its uniform, sky-blue color and lack of matrix.
Zircon is a primary mineral that crystallizes directly from magma. It forms in igneous rocks like granite and syenite and is also found in metamorphic rocks. As an accessory mineral, it is widespread but gem-quality crystals are less common. Major sources of gem zircon include Sri Lanka (Ceylon), Cambodia, Myanmar (Burma), Australia, and the United States (especially in the states of Arkansas and North Carolina). The blue variety of zircon is typically heat-treated to achieve its vibrant color, as natural blue zircon is rare.
Tanzanite is a variety of the mineral zoisite and is found in only one location on Earth: the Merelani Hills near Mount Kilimanjaro in Tanzania. Its formation is unique, believed to have occurred under specific geological conditions involving the metamorphism of limestone and the presence of trace elements like vanadium. This extreme rarity is a primary factor in its high value and cost. The mining area is small, leading to concerns about the long-term supply of the gemstone.
Blue Topaz is a silicate mineral that crystallizes in pegmatites and hydrothermal veins. While natural blue topaz exists, the vast majority of blue topaz on the market is created by irradiating colorless or pale yellow topaz. The natural sources for the base material include Sri Lanka, Brazil, Mexico, Nigeria, and the United States (Texas, Utah, and California). The treatment process to achieve the desired blue hue is a standard and stable industry practice.
Gemological Properties
Understanding the physical and chemical properties of these gemstones is crucial for appreciating their differences and determining their care. The table below summarizes key gemological data for each stone.
| Gemstone | Chemical Formula | Mohs Hardness | Crystal System | Refractive Index (approx.) | Key Characteristics |
|---|---|---|---|---|---|
| Turquoise | CuAl₆(PO₄)₄(OH)₈·4H₂O | 5 - 6 | Triclinic | 1.61 - 1.65 | Porous, often contains matrix (host rock), color can fade with prolonged exposure to light, heat, or chemicals. |
| Zircon | ZrSiO₄ | 6.5 - 7.5 | Tetragonal | 1.92 - 2.01 | High refractive index and strong dispersion ("fire"), can be brittle due to cleavage. Heat treatment is common for color enhancement. |
| Tanzanite | Ca₂Al₃(SiO₄)₃(OH) | 6.5 - 7 | Orthorhombic | 1.69 - 1.70 | Pleochroic (shows different colors from different angles: blue, violet, burgundy). Often heated to enhance color and remove brown undertones. |
| Blue Topaz | Al₂SiO₄(F,OH)₂ | 8 | Orthorhombic | 1.61 - 1.63 | High durability for everyday wear. The vast majority of blue topaz on the market is irradiated to achieve its color. |
Turquoise is the softest and most porous of the group, making it susceptible to damage from chemicals, heat, and prolonged sunlight. Its hardness can vary depending on its water and copper content. High-quality turquoise is often stabilized with a resin or wax to improve its durability and color retention.
Zircon is notable for its exceptional brilliance and fire, which are due to its high refractive index and strong dispersion. However, it can be brittle due to its cleavage planes, meaning it can split if struck with force. It is also heat-sensitive and should not be subjected to high temperatures during jewelry repair.
Tanzanite is prized for its strong pleochroism, displaying a dramatic shift from blue to violet to reddish-brown depending on the viewing angle. This property requires careful cutting to showcase the most desirable blue-violet hue. It is often heated to around 600°C to dissolve the brownish color zones and produce a uniform, vibrant blue. This treatment is permanent and stable.
Blue Topaz is the hardest and most durable of the December stones, with a Mohs hardness of 8. This makes it an excellent choice for rings and jewelry that will be worn daily. Its color, typically a rich, saturated blue, is almost always the result of irradiation followed by annealing. This process is stable and does not fade over time with normal wear.
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, each December birthstone carries a wealth of symbolic meaning and metaphysical beliefs that have been passed down through generations.
Turquoise is universally regarded as a stone of protection, healing, and good fortune. Its lore as a protective talisman is ancient, believed to guard against accidents, violence, and negative energy. It is often called the "master healer" and is associated with calming emotions, promoting inner peace, and fostering self-forgiveness. In many cultures, it is a stone of friendship and love, meant to be gifted to preserve and strengthen bonds. Its connection to the sky and water elements symbolizes tranquility and spiritual grounding.
Zircon is associated with clarity, wisdom, and spiritual grounding. It is believed to enhance mental clarity, focus, and memory. Some traditions hold that zircon can help its wearer connect with their higher self and gain deeper spiritual insight. It is also thought to promote prosperity and honor, making it a stone for those seeking success in their endeavors. The blue variety, in particular, is linked to peace and tranquility.
Tanzanite is a stone of transformation, intuition, and new beginnings. As a relatively new gemstone, its metaphysical properties are modern but potent. It is believed to facilitate spiritual awakening and higher consciousness, opening the mind to new perspectives and ideas. Its shifting colors are seen as a metaphor for change and the journey of self-discovery. It is also associated with calming an overactive mind and relieving stress, making it a stone for meditation and introspection.
Blue Topaz symbolizes communication, clarity of thought, and calm. It is believed to help express one's thoughts and feelings more clearly and effectively. As a stone of peaceful energy, it is thought to soothe anger, release tension, and promote relaxation. Its durable nature is metaphorically linked to resilience and stability, helping its wearer navigate life's challenges with a calm and clear mind.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of any gemstone. The differing physical properties of the December birthstones require specific attention.
Turquoise requires the most gentle handling. Due to its porosity, it should be protected from chemicals, including household cleaners, cosmetics, perfumes, and even sweat. Clean it only with a soft, dry cloth. Avoid ultrasonic cleaners and steam cleaning, as they can damage the stone and any stabilizing treatments. Store turquoise jewelry separately to prevent scratching by harder gems.
Zircon is relatively durable but can be brittle. Avoid knocks and impacts, especially in settings like rings that are prone to contact. To clean, use warm, soapy water and a soft brush. Avoid sudden temperature changes, as zircon can be damaged by thermal shock. Ultrasonic cleaners are generally safe, but steam cleaning is not recommended.
Tanzanite is also somewhat brittle and should be protected from hard blows. It is sensitive to heat, so it should not be exposed to high temperatures during repair work. Clean with warm, soapy water and a soft brush. Ultrasonic cleaners and steam cleaning are not recommended, as the vibrations and heat can potentially damage the stone.
Blue Topaz is the most durable of the group, making it relatively easy to care for. It can be cleaned with warm, soapy water and a soft brush. Ultrasonic cleaners are generally safe for untreated or heat-treated topaz, but caution is advised for irradiated stones (though modern treatments are stable). It is resistant to chemicals and heat, making it suitable for daily wear with minimal special precautions.
Conclusion
The December birthstones—Turquoise, Zircon, Tanzanite, and Blue Topaz—offer a remarkable diversity that reflects the complexity and richness of the month itself. From the ancient, protective talisman of turquoise to the brilliant, fiery sparkle of zircon, the transformative violet hues of tanzanite, and the durable, serene blue of topaz, each stone tells a unique story. Their histories span millennia and continents, their geology speaks to the dynamic processes of our planet, and their properties provide both beauty and practical considerations for jewelry. The expansion of the December birthstone list is a testament to the evolving nature of gemology and commerce, providing individuals with a palette of blue options to suit their personal style, budget, and spiritual inclinations. Whether chosen for its historical significance, its symbolic meaning, or simply its captivating color, any of these four gemstones provides a meaningful and beautiful connection to the month of December.