December is unique among the months, boasting not one, but four official birthstones. This abundance offers a remarkable spectrum of color, history, and symbolism, perfectly mirroring the multifaceted nature of the year's final month. The traditional and modern birthstones for December are Turquoise, Tanzanite, Blue Zircon, and Blue Topaz, each a distinct gemstone with its own story, properties, and allure. While all are celebrated for their captivating blue hues—ranging from the soft sky tones of turquoise to the deep, shifting blues of tanzanite—they vary significantly in terms of origin, durability, and value. This article delves into the geological formation, historical lore, gemological properties, and cultural significance of each of these four December jewels, providing a thorough exploration for gemstone enthusiasts, jewelry buyers, and students of gemology.
The inclusion of multiple stones for December is a relatively modern development. The National Association of Jewelers standardized the unofficial American birthstones in 1912, combining historical customs with gemstones deemed practical for the jewelry industry. This list has evolved over time; zircon was added in 1952, and tanzanite was included in 2002. The reason for December's four options is not definitively known, though some speculate it was to provide more affordable choices and a greater variety of colors and styles for consumers. Each stone captures a different facet of December's chill beauty, from the ancient allure of turquoise to the modern discovery of tanzanite, the dazzling sparkle of zircon, and the popular affordability of blue topaz.
History and Lore
The historical significance of December's birthstones spans millennia and continents, reflecting a rich tapestry of human belief and adornment.
Turquoise is one of the oldest known gemstones in human history, cherished for millennia. Its use dates back over 3,000 years in China, where artisans carved it into intricate objects. In ancient Egypt, pharaohs and other rulers adorned themselves with turquoise, considering it a stone of power and protection. The turquoise birthstone was thought to possess many beneficial powers, like guaranteeing health and good fortune. From the 13th century onward, a widespread European belief held that turquoise could protect the wearer from falling, particularly off horses, and would break into several pieces at the approach of disaster. Hindu mystics believed that seeing a turquoise after beholding the new moon ensured fantastic wealth. In Native American cultures, particularly among the Apache, turquoise held deep spiritual significance; they believed it could be found by following a rainbow to its end. The stone's name is derived from the French "pierre tourqueise," meaning "Turkish stone," as it was brought to Europe from Persian mines via Turkish trade routes.
Zircon has a long and storied history, often mistaken for diamond due to its high brilliance and fire. The name "zircon" may come from the Persian "zargun," meaning gold-colored, though it is most prized today for its brilliant blue varieties. Historically, zircon was believed to promote honor and purity in its wearer. Its remarkable sparkle led to its use in medieval times as a diamond simulant. While its specific historical lore is less documented than that of turquoise, its association with clarity, wisdom, and balance speaks to its enduring value as a gemstone of insight and spiritual grounding.
Tanzanite is the newest of the four, a recent addition to the gemological world. It was discovered in the 1960s in a single small area of Tanzania, hence its name. Due to its extreme rarity—found only in one location on the planet—it is considered one of the most valuable of the December stones. Its modern symbolism is tied to transformation and new beginnings, a fitting narrative for a stone that was virtually unknown a few decades ago. Its rapid rise to prominence in the jewelry market and its addition to the birthstone list in 2002 highlight how birthstone traditions can evolve with new discoveries.
Blue Topaz has a more ambiguous historical origin. The exact historical origin of blue topaz is unknown, as it has been found throughout history. The name "topaz" itself is believed to originate from the Sanskrit word "tapas," meaning fire, or from the Greek "Topazios," the ancient name of an island in the Red Sea. However, the stones from this island were later discovered to be peridot, but the name stuck. Historically, topaz was associated with strength and protection. In modern times, blue topaz, specifically, has become known as a symbol of love, fidelity, and clarity, making it a popular choice for romantic jewelry gifts.
Geological Formation and Sources
The formation and mining locations of each December birthstone are as diverse as their histories.
Turquoise is an opaque mineral, a hydrous phosphate of copper and aluminum. It forms in arid regions where acidic, copper-rich groundwater reacts with minerals containing aluminum and phosphorus. This process occurs in the near-surface environment, creating veins and nodules that are mined. Major sources of turquoise include the United States (particularly in the Southwest), Iran, China, and Egypt. The stone often contains a "matrix," which are remnants of the host rock in which it formed, appearing as veins or web-like patterns within the gem. The color of turquoise ranges from soft sky blue to greenish hues, depending on the specific copper and iron content during formation.
Zircon is a zirconium silicate (ZrSiO₄) and is one of the oldest minerals on Earth, with crystals found in ancient geological formations. It forms in igneous and metamorphic rocks. Blue zircon, the variety celebrated as a December birthstone, is typically heat-treated from brown zircon to achieve its desirable color. Natural blue zircon is rare. Zircon is mined in various locations worldwide, including Sri Lanka, Cambodia, Myanmar, and Australia. It is known for its high refractive index and strong dispersion, which gives it exceptional brilliance and fire.
Tanzanite is a variety of the mineral zoisite, colored by traces of vanadium. Its formation is geologically unique. It is found only in the Merelani Hills of Tanzania, in a small area of less than 8 square kilometers. The gemstone formed from the metamorphism of limestone under high heat and pressure, a process that occurred about 585 million years ago. The specific geological conditions that created tanzanite are not believed to exist anywhere else on Earth, which underscores its rarity. Mining is limited to this single, localized source, making it a finite resource.
Blue Topaz is a silicate mineral with the chemical formula Al₂SiO₄(F,OH)₂. It crystallizes in igneous rocks, particularly in pegmatites and rhyolites. While natural blue topaz exists, it is exceedingly rare. The vast majority of blue topaz on the market is produced by irradiating and heat-treating colorless or pale yellow topaz to induce a blue color. This treatment is stable and permanent. Topaz is mined in several countries, including Sri Lanka, Brazil, Mexico, Nigeria, and the United States. In the U.S., it is notably found in Texas, where it is the official state gemstone, as well as in Utah and California.
Gemological Properties
Understanding the physical and optical properties of these gemstones is crucial for their identification, valuation, and care.
| Gemstone | Chemical Composition | Mohs Hardness | Crystal System | Typical Treatments | Key Optical Properties |
|---|---|---|---|---|---|
| Turquoise | CuAl₆(PO₄)₄(OH)₈·4H₂O | 5 - 6 | Triclinic | Stabilization (waxing, impregnation) | Opaque, waxy luster, refractive index ~1.61 |
| Zircon | ZrSiO₄ | 6.5 - 7.5 | Tetragonal | Heat treatment (for blue color) | High refractive index (1.92-1.98), strong dispersion |
| Tanzanite | Ca₂Al₃(SiO₄)₃(OH) | 6.5 - 7 | Orthorhombic | Heat treatment (commonly required) | Pleochroic (blue, violet, burgundy), trichroic |
| Blue Topaz | Al₂SiO₄(F,OH)₂ | 8 | Orthorhombic | Irradiation and heat treatment | Transparent, vitreous luster, refractive index ~1.63 |
Turquoise is a relatively soft gemstone, ranking between 5 and 6 on the Mohs hardness scale, which makes it susceptible to scratching and abrasion. It is typically opaque to semi-translucent and has a waxy to vitreous luster. Due to its porosity, turquoise is often stabilized with wax or resin to enhance its durability and color. The presence of matrix (the host rock) is a natural characteristic and does not necessarily detract from its value if it is aesthetically integrated.
Zircon is significantly harder and more durable than turquoise, with a Mohs hardness ranging from 6.5 to 7.5. This makes it suitable for all types of jewelry, including rings. It has a high refractive index and strong dispersion, giving it a brilliance and fire that can rival diamond. Blue zircon is almost always the result of heat treatment applied to brown zircon crystals. The blue color is typically a bright, clear blue.
Tanzanite has a Mohs hardness of 6.5 to 7, making it moderately durable but more fragile than topaz or sapphire. It is strongly pleochroic, meaning it shows different colors when viewed from different crystal directions—typically blue, violet, and burgundy. This characteristic is a key identifier for the gem. Most tanzanite on the market has been heat-treated to remove the brownish-yellow hues and enhance its blue-to-violet color, a process that is considered permanent and stable.
Blue Topaz is the hardest and most durable of the four December birthstones, with a Mohs hardness of 8. This makes it an excellent choice for everyday wear, especially in rings and bracelets. It is transparent with a vitreous luster and is typically cut to maximize its brilliance. As noted, the blue color is almost always the result of treatment. The intensity of the blue can vary, from light "Sky Blue" to the deeper "London Blue" and "Swiss Blue" shades.
Symbolism and Metaphysical Beliefs
The metaphysical properties attributed to these stones are as varied as their origins.
Turquoise has long been considered a stone of protection, healing, and good fortune. It was believed to ward off negative energy and bring peace to the wearer. Its association with health was strong; it was thought to cure ailments and ensure a long life. The belief that it would break to warn of impending danger is a testament to its role as a protective talisman. For many cultures, especially in the Americas, turquoise is a sacred stone connecting the wearer to the earth and sky.
Zircon is associated with clarity, wisdom, and spiritual balance. It is believed to help organize one's thoughts, promote clarity of mind, and enhance intuition. Historically, it was thought to bring honor and purity to the wearer. Its brilliant sparkle is often linked to the idea of enlightenment and the attainment of wisdom.
Tanzanite, as a modern discovery, carries symbolism aligned with its unique origin and appearance. It is often associated with transformation, spiritual awakening, and new beginnings. Its striking trichroic nature—showing three colors—symbolizes the ability to see situations from multiple perspectives. It is considered a stone of intuition and higher consciousness.
Blue Topaz is linked to calmness, love, and clarity. Its serene blue color is believed to promote relaxation, reduce stress, and foster open communication. It is often associated with emotional balance and is considered a stone of truth and forgiveness. Its modern symbolism as a gem of love and fidelity makes it a popular choice for engagement and anniversary jewelry.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of these gemstones, and their care instructions are dictated by their physical properties.
Turquoise requires the most careful handling due to its softness and porosity. It should be cleaned with a soft, dry cloth. Avoid exposing it to chemicals, cosmetics, perfumes, and even prolonged water immersion, as these can cause discoloration or damage the stabilizing treatments. It should be stored separately from other jewelry to prevent scratching.
Zircon is relatively durable but can be brittle. While hard, it has poor toughness, meaning it can chip or abrade if struck hard. Clean it with warm water, mild soap, and a soft brush. Ultrasonic and steam cleaners are generally safe, but caution is advised due to its potential brittleness.
Tanzanite is moderately hard but has perfect cleavage in one direction, making it susceptible to splitting if struck with force. It should be protected from sharp blows and extreme temperature changes. Cleaning with warm, soapy water and a soft brush is recommended. Avoid ultrasonic and steam cleaners, as vibrations and heat can cause damage.
Blue Topaz, being the hardest of the group, is the most durable for daily wear. It can be cleaned with warm, soapy water and a soft brush. It is generally safe for ultrasonic cleaning, but steam cleaning should be avoided if the stone has been fracture-filled (though this is less common for blue topaz compared to other varieties). Due to its hardness, it is less likely to scratch but should still be stored carefully to avoid contact with harder gems like diamonds or sapphires.
Conclusion
The four birthstones of December—Turquoise, Tanzanite, Blue Zircon, and Blue Topaz—offer a remarkable journey through geological time, human history, and artistic expression. From the ancient, protective talisman of turquoise to the modern, transformative allure of tanzanite; from the brilliant, diamond-like fire of zircon to the durable, serene beauty of blue topaz, each gemstone provides a unique connection to the winter month. Their shared blue color palette evokes the icy skies and deep waters of the season, yet their individual stories, properties, and symbols cater to a wide range of personal tastes and beliefs. For those born in December, the choice among these four jewels is not merely a matter of color but an opportunity to select a stone that resonates with their personal history, style, and spiritual inclinations. Together, they form a cohesive yet diverse group, ensuring that every December birthday can be adorned with a gemstone as special and multifaceted as the month itself.