December is a month of deep twilight, icy landscapes, and festive celebration. Its birthstones reflect this cool, serene palette, offering a spectrum of blue from the earthy sky of turquoise to the electric violet of tanzanite, the fiery sparkle of zircon, and the crisp brilliance of blue topaz. While most months are assigned a single gem, December boasts a unique collection, each with its own distinct history, geological origin, and symbolic meaning. This diversity provides a wealth of choice for those born in the final month of the year, allowing for personal expression through color, durability, and lore. The following guide delves into the characteristics, origins, and significance of these four remarkable gemstones, drawing upon gemological data and historical accounts to provide a comprehensive overview for enthusiasts, collectors, and students of gemology.
Historical and Cultural Significance
The tradition of birthstones is ancient, with roots often traced to the biblical description of Aaron’s breastplate in the Book of Exodus, which featured twelve gemstones representing the twelve tribes of Israel. Later, in the 1st century AD, the historian Josephus linked these stones to the twelve signs of the zodiac, establishing a connection between gems and specific periods of the year. This concept evolved over centuries, culminating in the modern standardized lists. For December, the journey to its current collection was gradual.
Turquoise is one of the oldest known gemstones in human adornment, with a history spanning millennia. It was a favored gem for amulets in ancient civilizations, prized for its ease of cutting and ability to hold inscriptions. Historical sources note that turquoise was found in Persia and along the Sinai Peninsula, and it reached European markets through Constantinople, Turkey, which influenced its name. The stone was deeply embedded in various cultures: Tibetans considered it a birthstone of fortune, health, and success, and it was so valued that it was often used as currency. Ancient Incas and Mayas offered turquoise as gifts to their gods, while Native American tribes of the Southwest associated the gem with youth and strength. Its protective powers were widely believed; it was thought to warn its wearer of approaching illness or danger by becoming pale, and it was prized by lovers and married couples as a gem that protected relationships and preserved friendship when gifted.
The other December stones have more recent histories. Tanzanite is a modern discovery, found only in Tanzania. Its origin story is attributed to a Maasai tribesman in 1967. A Maasai legend claims that the ground was struck by a bolt of lightning from the sky, turning all the rocks a shimmering blue. For the Maasai tribe, tanzanite is a gift given upon the birth of a baby, symbolizing health, well-being, and wealth. Historically, it was believed to strengthen the immune system, detoxify blood, and regenerate cells, skin, and hair. Its association with new beginnings, transformation, and intuition has made it a popular stone for modern metaphysical beliefs. In 2002, the American Gem Trade Association officially added tanzanite as a birthstone for December, solidifying its place in the contemporary list. It is also recognized as the stone for the 8th and 24th wedding anniversaries.
Zircon, often confused with the synthetic cubic zirconia, is one of the oldest minerals on Earth, with some specimens dating back over 4.4 billion years. However, its use as a gemstone is also ancient, with blue zircon being particularly prized. While its historical lore is less documented in the provided sources compared to turquoise, it has long been associated with clarity, wisdom, and balance. Its brilliant fire and sparkle have made it a popular diamond simulant throughout history.
Blue Topaz is the newest addition to the December family, though topaz itself has been known since antiquity. The use of blue topaz as a birthstone is a more modern development, driven by its availability and desirable icy blue color. It is often treated to achieve its blue hue, a common practice in the gem trade. Its inclusion expanded the color options for December-born individuals, offering a durable and brilliant alternative.
The American Gem Trade Association (AGTA) and the Jewelers of America (JA) recognize the modern birthstone list, which for December includes turquoise, zircon, and tanzanite. Blue topaz is widely accepted as an alternative or additional stone, particularly in commercial jewelry.
Geological Formation and Sources
Each December birthstone forms under unique geological conditions, resulting in distinct physical and chemical properties.
Turquoise is a secondary mineral that forms in arid regions where acidic, copper-rich water percolates through rocks containing aluminum and phosphorus. It is found in a "host rock," typically a porous rock like sandstone or limestone, where it fills cavities and veins. The finest turquoise comes from Iran (historically Persia), but significant deposits are also found in the United States (especially Arizona and New Mexico), China, Mexico, and Egypt. The provided sources note that turquoise is found worldwide.
Tanzanite is unique in that it is found in only one location on Earth: the Merelani Hills of northern Tanzania, near Mount Kilimanjaro. It is the blue to blue-violet to purple variety of the mineral zoisite, colored by trace amounts of vanadium. Its formation is linked to a specific geological event—the heating of zoisite by regional metamorphism—which created the conditions for tanzanite to develop. The limited geographic source makes it exceptionally rare.
Zircon is a zirconium silicate mineral that forms in igneous and metamorphic rocks. Major sources include Sri Lanka, Cambodia, Australia, and Myanmar. The blue variety, which is most associated with December, is typically heat-treated to enhance or create its color, as natural blue zircon is relatively rare. It is found in alluvial deposits (gravels and sands) where weathering has released the hard, durable crystals.
Blue Topaz forms in igneous rocks, particularly in pegmatites and high-temperature veins. While topaz crystals are found in many locations, including Brazil, Nigeria, Sri Lanka, and the United States, the vibrant blue color seen in jewelry is almost always the result of irradiation and heat treatment of colorless or pale yellow topaz. Natural blue topaz is extremely rare. The provided sources list its geographic origin as "worldwide."
Gemological Properties
Understanding the physical properties of these gemstones is crucial for their identification, valuation, and care. The following table summarizes key data for the four December birthstones, based on information from the provided sources.
| Property | Tanzanite | Turquoise | Zircon | Blue Topaz |
|---|---|---|---|---|
| Natural Color | Blue to violet | Sky blue to greenish | Blue | Pale blue to dark blue |
| Mohs Hardness | 6 to 7 | 5 to 6 | 6.5 to 7.5 | 8 |
| Heat Treatment | Common | Stabilization common | Common | Common |
| Best For | Occasional rings, earrings, pendants | Earrings, pendants, beads | Earrings, pendants, and protected rings | Daily wear rings, all jewelry |
| Sensitivity | Prone to chipping | Sensitive to chemicals and moisture | Brittle at edges | Sensitive to sharp impacts |
| Chemical Composition | Zoisite (Ca2Al3(SiO4)3(OH)) | Hydrated copper aluminum phosphate (CuAl6(PO4)4(OH)8·4H2O) | Zirconium silicate (ZrSiO4) | Topaz (Al2SiO4(F,OH)2) |
| Geographic Origin | Tanzania only | Worldwide | Sri Lanka, Cambodia, Australia | Worldwide |
Tanzanite is the blue variety of zoisite, colored by vanadium. Its hardness ranges from 6 to 7 on the Mohs scale, making it relatively durable but susceptible to chipping due to its cleavage. It is commonly heat-treated to enhance its blue color, a stable process that mimics the natural geological heating that created the gem.
Turquoise is a phosphate mineral with a hardness of 5 to 6, making it one of the softer gemstones. It is often found in a porous, chalky state and is commonly stabilized with resins or waxes to improve its durability and color—a process known as stabilization. It is sensitive to chemicals, moisture, and prolonged exposure to skin oils, which can cause discoloration.
Zircon is a dense, brilliant gem with a hardness of 6.5 to 7.5. It is known for its exceptional refractive index and fire, often rivaling that of diamond. However, it can be brittle, especially at its edges, and is prone to chipping if struck. Most blue zircon on the market is heat-treated from brownish or greenish zircon. It should be protected from sharp impacts and extreme temperature changes.
Blue Topaz is a silicate mineral with a hardness of 8, making it one of the hardest and most durable of the December stones, suitable for everyday wear. Its color is almost always the result of treatment, typically irradiation followed by heat. While durable, it can be sensitive to sharp impacts, which may cause fractures along cleavage planes. It is generally low-maintenance and can be cleaned with mild soapy water.
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, December birthstones are imbued with rich symbolism and metaphysical properties, which have been attributed to them across different cultures and eras.
Turquoise is universally regarded as a stone of protection, grounding, and good fortune. It is seen as a steadying force, offering calm and balance in times of chaos. Historically, it was believed to warn of danger or illness by changing color. For lovers and married couples, it was a symbol of fidelity and enduring friendship. Tibetans viewed it as a key to health, success, and fortune, while Native Americans linked it to youth and strength. Its association with the sky and water in many cultures reinforces its calming and protective qualities.
Tanzanite is deeply connected to themes of transformation, new beginnings, and intuition. Its vivid blue-violet hue is said to represent the feeling of stepping into a new chapter with clarity and curiosity. It is believed to raise consciousness, dissolve old patterns and habits, and enhance psychic abilities. For the Maasai people, it is a blessing symbolizing health, well-being, and wealth, often given at births. Historically, it was thought to have healing properties for the immune system, blood, and cellular regeneration.
Zircon is associated with clarity, wisdom, and mental focus. It is believed to sharpen the mind and promote a sense of balance and stability. Its brilliant sparkle is thought to reflect inner clarity and truth. While less documented in ancient lore within the provided sources, its enduring presence as a gemstone suggests a long-standing appreciation for its light-reflecting qualities, which may have contributed to its symbolic link with wisdom and enlightenment.
Blue Topaz, with its icy, serene color, is often linked to calm, communication, and creativity. It is believed to soothe the mind, reduce stress, and encourage honest expression. Its durability and clarity make it a symbol of strength and resilience. While its metaphysical properties are more modern compared to turquoise, it is embraced for its cooling and calming energy, aligning with the tranquil imagery of winter.
Care and Maintenance
Proper care is essential to preserve the beauty and integrity of these gemstones, given their varied physical properties.
Turquoise requires the most careful handling. Due to its porosity and softness, it should be protected from chemicals, including perfumes, lotions, and cleaning agents. Avoid prolonged exposure to water, which can cause the stone to become unstable or change color. Clean turquoise jewelry with a soft, dry cloth. If necessary, use a slightly damp cloth, but dry it immediately. Avoid ultrasonic cleaners and steam cleaners.
Tanzanite is relatively durable but has perfect cleavage in one direction, making it susceptible to chipping or cracking from sharp blows. It should not be subjected to sudden temperature changes, extreme heat, or steam cleaning, as these can cause damage. Clean tanzanite with a soft brush and warm, soapy water, then dry thoroughly with a soft cloth. It is best suited for earrings, pendants, and occasional-wear rings where it is less likely to be knocked.
Zircon is hard but brittle. It should be protected from sharp impacts and rough handling. Avoid ultrasonic cleaners and steam, as these can cause fractures, especially if the stone has inclusions or has been treated. Clean zircon with warm, soapy water and a soft brush. Store it separately from other jewelry to prevent scratching.
Blue Topaz, with a hardness of 8, is the most durable of the group and can be worn in daily jewelry. However, it is still sensitive to sharp impacts, which can cause cleavage. It is generally safe to clean with warm, soapy water and a soft brush. Avoid harsh chemicals and extreme temperature changes. Ultrasonic cleaners are usually safe for untreated blue topaz, but caution is advised for treated stones.
Conclusion
December’s birthstones offer a remarkable diversity in color, origin, and character. From the ancient, protective turquoise to the modern, transformative tanzanite; the brilliant, clarifying zircon; and the durable, icy blue topaz, each gem provides a unique connection to the month’s wintry essence. Their selection is not merely a matter of birth month but a reflection of personal preference in color, style, and symbolic meaning. Understanding their geological backgrounds, gemological properties, and historical significance allows for a deeper appreciation of these gems, whether one is selecting a piece of jewelry, studying gemology, or simply exploring the rich tapestry of birthstone lore. Together, they form a cohesive yet varied collection that captures the serene and sparkling spirit of December.