The month of December is uniquely endowed in the world of gemology, holding the distinction of being the only month with four official birthstones: Turquoise, Zircon, Tanzanite, and Blue Topaz. This remarkable quartet offers a diverse palette of colors, from the iconic sky-blue of turquoise to the fiery brilliance of zircon and the serene blues of tanzanite and topaz. Each stone carries its own rich history, geological story, and set of gemological properties, providing a wealth of options for those born in the final month of the year. This article delves into the characteristics, origins, and lore of these four December birthstones, offering a comprehensive guide for enthusiasts, collectors, and jewelry buyers.
History and Lore of December's Birthstones
The tradition of assigning specific gemstones to birth months has evolved over centuries, with the modern list solidified in the early 20th century. The National Association of Jewelers in the United States released the first modern birthstone list in 1912, which has been periodically updated. Notably, spinel was introduced as a modern birthstone for August in 2016, demonstrating that these lists can adapt to market trends and gemstone popularity. For December, the four stones each possess distinct historical narratives and cultural symbolism.
Turquoise is arguably the most ancient of the December stones. Cherished since antiquity, it was a favorite of royalty, including the famed Egyptian pharaoh King Tutankhamun. Historical records indicate that turquoise was valued for its protective qualities, believed to safeguard the wearer from harm, falls, and negative energy. Its symbolism has endured through the ages; in contemporary culture, turquoise is associated with wisdom, tranquility, and friendship. The stone’s connection to winter is also noted, as its light blue and green hues complement the cool color palette of the season.
Zircon has a long and sometimes misunderstood history. The etymology of its name is debated, with some scholars tracing it to the Arabic zarkun (cinnabar or vermilion) and others to the Persian zargun (gold-colored). This ambiguity reflects the stone’s broad color range, which includes red, orange, yellow, brown, green, and blue. For centuries, colorless zircon was prized for its brilliance and flashes of multicolored light, known as "fire," leading to frequent confusion with diamond. During the Middle Ages, zircon was thought to induce deep sleep and repel evil spirits. In Hindu tradition, zircon is one of the nine gems of the navaratna, a set believed to protect the wearer and confer wealth, wisdom, and good health when worn together. The Victorian era also showed a particular fondness for blue zircon.
Tanzanite is a relatively recent addition to the gemological world, first discovered in the mid-20th century. Its rapid rise to prominence is a testament to its unique beauty and rarity. While its historical lore is not as ancient as that of turquoise or zircon, it has quickly developed modern associations with transformation and a connection to the natural world, given its exclusive geographic origin.
Blue Topaz, while part of the topaz family which includes a range of colors, has become a celebrated modern birthstone. Topaz itself has been known since antiquity, but the vibrant blue varieties that are popular today are often the result of treatment processes. The stone is noted for its durability and has been associated with various beliefs across different cultures, though its specific lore as a December stone is more modern.
Geological Formation and Sources
The geographic origins of these four stones are as varied as their appearances, each tied to specific geological conditions.
Turquoise is a secondary mineral formed in arid regions where acidic, copper-rich groundwater percolates through rocks containing aluminum and phosphorus. The most significant sources are located in the southwestern United States (particularly Arizona and New Mexico), Iran, Egypt, China, Mexico, and parts of Central Asia and Africa. The stone is often characterized by its matrix, a web-like pattern of host rock that can add distinctive color and texture. The presence of copper contributes to its blue hues, while iron can create green variations.
Zircon is a zirconium silicate mineral that forms in various geological environments, including igneous, metamorphic, and sedimentary rocks. It is a common mineral in many types of rock but gem-quality crystals are rarer. While not specified in the provided sources, zircon is mined in several countries, including Cambodia, Sri Lanka, and Australia. The stone’s color can be influenced by trace elements and heat treatment, which is often used to enhance or change its color, particularly to produce the coveted blue hues.
Tanzanite is one of the world's most recently discovered gemstones. It was first identified in the Merelani Hills of northern Tanzania in 1967. Geologically, it is a variety of the mineral zoisite, and its formation is linked to specific tectonic and thermal events. Its exclusive origin in a small area of Tanzania makes it significantly rarer than many other gemstones. Some estimates suggest that tanzanite is up to 1,000 times rarer than diamond, with experts believing the primary source may be depleted within a few decades.
Blue Topaz is a variety of the topaz mineral, which is a silicate of aluminum and fluorine. Natural blue topaz is very rare; most of the vibrant blue topaz available in the market today is produced by irradiating and heating colorless or pale blue topaz. The primary sources for topaz include Brazil, Sri Lanka, Pakistan, and the United States (particularly Texas). The stone forms in igneous rocks, often in pegmatites, and can be found in large crystal formations.
Gemological Properties
Understanding the physical and chemical properties of these gemstones is crucial for their identification, valuation, and care. The following table summarizes key gemological data for the four December birthstones, based on the provided sources.
| Gemstone | Chemical Composition | Mohs Hardness | Typical Colors | Key Properties & Notes |
|---|---|---|---|---|
| Turquoise | Hydrated copper/aluminum phosphate | 5 - 6 | Light blue to green | Often exhibits a matrix (host rock) pattern. |
| Zircon | Zirconium silicate (ZrSiO₄) | 6.5 - 7.5 | Wide range: red, orange, yellow, brown, green, blue, colorless | High refractive index and strong fire; can be confused with diamond. |
| Tanzanite | Calcium aluminum silicate hydroxide (variety of zoisite) | 6.5 - 7 | Blue to violet, often with pleochroism (showing different colors from different angles) | Heat treatment is standard to enhance color. |
| Blue Topaz | Aluminum silicate with fluorine and hydroxyl | 8 | Blue (often treated) | Very durable; natural blue topaz is extremely rare. |
Turquoise ranks lower on the Mohs hardness scale, between 5 and 6, making it relatively soft and susceptible to scratching and damage from sharp impacts. Its porous nature also means it can absorb oils and chemicals, which may alter its color over time.
Zircon is notably harder, with a Mohs hardness of 6.5 to 7.5, making it more suitable for jewelry that will see regular wear, though it can still be chipped due to its cleavage. Its most celebrated optical property is its high refractive index and strong dispersion, which gives colorless zircon its diamond-like fire.
Tanzanite has a Mohs hardness of 6.5 to 7. While not as soft as turquoise, it is still considered a gem that requires careful handling. It is not recommended for daily wear in rings without a protective setting, as it is susceptible to chipping and abrasion. Its most defining characteristic is its strong pleochroism, where a single stone can appear blue, violet, and burgundy depending on the crystal orientation and viewing angle. Heat treatment is a standard and permanent practice to transform the naturally brownish zoisite into the desirable blue-violet tanzanite.
Blue Topaz is the most durable of the four, with a hardness of 8 on the Mohs scale. This makes it an excellent choice for all types of jewelry, including rings intended for daily wear. The blue color in commercially available topaz is almost always the result of irradiation and heat treatment, a process that is stable and does not fade. Natural blue topaz is exceptionally rare and usually pale in color.
Symbolism and Metaphysical Beliefs
Across cultures and eras, gemstones have been imbued with symbolic meaning and metaphysical properties. The December birthstones are no exception, each carrying a legacy of beliefs.
Turquoise has been revered for millennia as a protective talisman. Ancient warriors and travelers wore it to guard against injury and evil forces. Its symbolism has evolved to represent wisdom, tranquility, and enduring friendship, making it a popular gift to signify loyalty and emotional balance.
Zircon has been associated with sleep and spiritual protection. Medieval Europeans believed it could induce peaceful slumber and ward off nightmares and evil spirits. In Hindu tradition, as part of the navaratna, it is linked to the planet Venus and is thought to bring prosperity and wisdom. Its association with clarity and purity, especially in its colorless form, has also made it a symbol of enlightenment.
Tanzanite, as a modern discovery, has quickly accumulated its own set of meanings. It is often described as a stone of transformation, said to facilitate a higher consciousness and spiritual awakening. Its exclusive origin in Tanzania has also tied it to the majesty of the African landscape, evoking themes of rarity and connection to the earth.
Blue Topaz is often associated with calm, clarity, and communication. In some metaphysical traditions, it is believed to soothe the mind, reduce stress, and encourage truthful expression. Its durability is sometimes metaphorically linked to emotional resilience and steadfastness.
Care and Cleaning
Proper maintenance is essential to preserve the beauty and integrity of any gemstone. The varying hardness and stability of the December birthstones necessitate different care approaches.
Turquoise requires the most careful handling. It should be protected from harsh chemicals, including cosmetics, perfumes, and even some cleaning agents. Cleaning should be done with a soft, dry cloth. Avoid ultrasonic cleaners, steam cleaners, and prolonged exposure to water, as it can cause the stone to crack or become discolored. Store turquoise jewelry separately to prevent scratching by harder gems.
Zircon is relatively hard but can be brittle. It is best to avoid sharp blows and extreme temperature changes, which can cause fracturing. Cleaning can be done with warm, soapy water and a soft brush. Ultrasonic cleaners are generally safe, but caution is advised for stones with inclusions or fractures. Steam cleaning is not recommended.
Tanzanite is sensitive to heat and pressure. As noted, it is not recommended for daily wear in rings due to its relative softness and cleavage. Cleaning should be done with warm, soapy water and a soft brush. Ultrasonic and steam cleaners are never recommended for tanzanite, as the vibrations and heat can cause damage. The stone should be stored carefully to avoid contact with harder materials.
Blue Topaz, with its high hardness of 8, is the most resilient of the group. It can withstand daily wear and is relatively easy to clean. Warm, soapy water and a soft brush are effective for routine cleaning. Ultrasonic and steam cleaners are generally safe for blue topaz, provided the stone is not fractured and the jewelry setting is secure. However, as with any gemstone, it is wise to inspect the setting regularly to ensure the stone is secure.
Conclusion
The four birthstones of December—Turquoise, Zircon, Tanzanite, and Blue Topaz—offer a remarkable diversity that caters to a wide range of tastes and preferences. From the ancient, protective turquoise to the brilliant, diamond-like zircon, the recently discovered and rare tanzanite, and the durable, vibrant blue topaz, each stone possesses a unique combination of history, geology, and beauty. Understanding their distinct properties, origins, and care requirements allows individuals to make informed choices, whether selecting a piece of jewelry for themselves or as a meaningful gift. Together, they form a captivating quartet that celebrates the richness of the natural world and the enduring allure of gemstones.