December holds a unique distinction in the world of gemstones: it is the only month with four officially recognized birthstones. This abundance offers a cool, wintry palette mirroring the season's icy skies and deep twilight blues, providing a diverse selection for those born in the final month of the year. The traditional birthstones for December are Turquoise, Tanzanite, and Blue Zircon, with Blue Topaz often considered a modern addition, particularly in the United States. Each of these gemstones carries its own rich history, distinct gemological properties, and symbolic meaning, making them ideal choices for jewelry and personal adornment. While some stones, like Turquoise, have been cherished for millennia, others, such as Tanzanite, are relatively modern discoveries, reflecting the evolving nature of the birthstone tradition itself.
The concept of birthstones can be traced back to ancient civilizations, including ancient Egypt, Greece, and Rome, where gemstones were believed to have mystical and healing properties. The modern list is largely based on the gemstones described in the Bible's book of Exodus, specifically the twelve stones set in the breastplate of Aaron, or the gems from the foundation of New Jerusalem. Over time, these ancient lists were adapted and standardized by various cultures and trade organizations. The expansion to include multiple stones for December in the 20th century—adding Blue Topaz and later Tanzanite—reflects both a growing appreciation for new gemstone discoveries and their commercial appeal, as well as a desire to offer more variety in color and style to suit personal preferences.
This article provides an in-depth exploration of these four December birthstones, drawing from historical, geological, and cultural sources to present a comprehensive overview for gemstone enthusiasts, jewelry buyers, and students of gemology.
History and Lore
The history of December's birthstones is a tapestry woven from ancient tradition and modern discovery. Turquoise is arguably the oldest of the four, with a lineage stretching back thousands of years. It has been cherished by royalty and commoners alike, from the pharaohs of ancient Egypt to King Tutankhamun, who was buried with turquoise adorned artifacts. In many cultures, this mineral was believed to protect its wearer from harm, including falls and negative energy, and was often associated with wisdom, tranquility, and friendship. Its journey to becoming a traditional December birthstone is deeply rooted in these ancient beliefs.
Blue Zircon also has a long history, though its identity has sometimes been confused with other blue stones like sapphire or topaz. Historically, zircon has been valued for its brilliance and fire, which can rival that of diamond. It has been associated with clarity, wisdom, and a sense of balance, beliefs that have persisted into the modern era. As one of the traditional December stones, it carries the weight of this historical significance.
The 20th century saw the addition of new stones to the December list. Blue Topaz was added later and quickly became part of the story, especially for anyone who loves a crisp winter blue with extra durability. While the name "Topaz" originates from the Greek word "Topazios," an ancient name for an island in the Red Sea, it is important to note that the stones from this island were later discovered to be Peridot, not topaz. Despite this historical mix-up, blue topaz has carved out its own niche as a popular modern birthstone.
The most recent addition is Tanzanite, discovered in the 20th century and officially added to the December birthstone list in 2002. Its discovery in a single known location in Tanzania gave it an immediate mystique, and its captivating blue-violet color captured the public's imagination. While it lacks the ancient lore of Turquoise or Zircon, it is often linked to shifts, growth, and fresh chapters in life, reflecting its modern origins and the sense of discovery it represents.
Geological Formation and Sources
Each of December's birthstones originates from distinct geological processes and is mined in specific regions around the world, which influences its availability and characteristics.
Turquoise is a secondary mineral formed in arid regions where acidic, copper-rich groundwater seeps through pre-existing rocks and reacts with minerals containing aluminum and phosphorus. This process occurs primarily in areas with specific weather conditions that facilitate its formation. The most significant sources include the southwestern United States (particularly Arizona and New Mexico), Iran, Egypt, China, Mexico, and parts of Central Asia and Africa. Turquoise is often known for its matrix-like look—the host rock that becomes part of the gem—creating a web-like pattern of color that adds to its distinctive character.
Tanzanite is a variety of the mineral zoisite and is found in only one location on Earth: the Merelani Hills of northern Tanzania, near Mount Kilimanjaro. Its formation is linked to a unique geological event where the host rock was subjected to intense heat and pressure, transforming the original zoisite into the vibrant blue-violet variety known as tanzanite. This single-source origin makes it exceptionally rare, and its discovery in the 1960s led to its rapid rise in popularity.
Blue Zircon is a mineral belonging to the zircon group, which is one of the oldest minerals on Earth, with crystals dating back billions of years. While zircon occurs in many colors, the blue variety is typically achieved through heat treatment of brown or yellow zircon crystals. Major sources for zircon include Sri Lanka, Cambodia, Myanmar, and Australia. The heat treatment process is a standard industry practice that enhances the stone's color and clarity, making the vibrant blue hues more marketable.
Blue Topaz is a silicate mineral that forms in igneous rocks, particularly granites and rhyolites. Natural blue topaz is quite rare; most of the blue topaz available in the market is the result of irradiation and heat treatment of colorless or pale topaz crystals. Major sources of topaz include Brazil, Sri Lanka, Nigeria, and the United States (notably Texas). The treatment process is stable and widely accepted in the gemological community, allowing for the production of consistent, vivid blue colors that range from pale sky blue to deep Swiss blue.
Gemological Properties
Understanding the physical and optical properties of these gemstones is crucial for their identification, valuation, and care. The following table summarizes key gemological data for each December birthstone, based on established standards.
| Gemstone | Chemical Composition | Mohs Hardness | Crystal System | Refractive Index (Typical) | Specific Gravity (Typical) | Key Characteristics |
|---|---|---|---|---|---|---|
| Turquoise | Hydrated copper & aluminum phosphate | 5 - 6 | Triclinic | 1.61 - 1.65 | 2.6 - 2.9 | Often porous, can be stabilized; color ranges from sky blue to greenish blue; matrix patterns common. |
| Tanzanite | Calcium aluminum silicate hydroxide | 6.5 - 7 | Orthorhombic | 1.69 - 1.70 | 3.35 | Pleochroic (shows blue, violet, and burgundy); often heat-treated to enhance color. |
| Blue Zircon | Zirconium silicate | 7.5 | Tetragonal | 1.92 - 1.98 | 4.6 - 4.7 | High refractive index and strong dispersion ("fire"); typically heat-treated from brown to blue. |
| Blue Topaz | Aluminum silicate fluoride hydroxide | 8 | Orthorhombic | 1.61 - 1.62 | 3.49 - 3.57 | Often treated (irradiation & heat) to achieve blue color; good durability for jewelry. |
Turquoise is relatively soft compared to the other December stones, with a Mohs hardness of 5 to 6. This makes it more susceptible to scratching and requires careful handling. Its chemical composition makes it porous, and many commercial turquoise stones are stabilized with resins or waxes to improve durability and color consistency. The presence of a matrix (the host rock) is a natural characteristic and not considered a flaw.
Tanzanite has a Mohs hardness of 6.5 to 7, making it suitable for jewelry but requiring care to avoid hard impacts. It is strongly pleochroic, meaning it can show different colors—blue, violet, and burgundy—when viewed from different angles. Most tanzanite on the market has been heat-treated to remove the brownish tones and enhance its signature blue-violet hue, a treatment that is permanent and stable.
Blue Zircon is one of the hardest of the December stones, with a Mohs hardness of 7.5. It is also known for its exceptional brilliance and fire, which are due to its high refractive index and strong dispersion. Most blue zircon is heat-treated to achieve its vivid blue color from naturally occurring brown or yellow crystals. It is generally considered a durable gemstone for jewelry, though it can be brittle and may chip if struck hard.
Blue Topaz is the hardest of the four, with a Mohs hardness of 8, making it very durable for everyday wear. Its color is almost always the result of treatment; natural blue topaz is exceedingly rare. The treatment process involves irradiation followed by heat treatment to stabilize the color, resulting in shades like sky blue, Swiss blue, and London blue. This treatment is permanent under normal conditions, and blue topaz is valued for its clarity and consistent color.
Symbolism and Metaphysical Beliefs
Across cultures and centuries, gemstones have been imbued with symbolic meanings and metaphysical powers. December's birthstones are no exception, each carrying a distinct set of beliefs that add to their allure.
Turquoise is widely regarded as a stone of protection, grounding, and good fortune. In many traditions, it is believed to ward off negative energy and bring peace of mind. Its calming blue and green hues are associated with tranquility and emotional balance. Historically, it was thought to be a sacred stone that connected the wearer to the spiritual world, and it remains a popular choice for those seeking wisdom and friendship.
Tanzanite, as a modern gemstone, has developed its own symbolism centered on transformation and new beginnings. Its unique color, which shifts with the light, is said to reflect the process of change and personal growth. It is often associated with clarity of mind and curiosity, encouraging those who wear it to step into new chapters of their lives with confidence and vision.
Blue Zircon is traditionally linked to clarity, wisdom, and mental focus. It is believed to enhance concentration and help the wearer make clear decisions. Some cultures also associate it with prosperity and good fortune, making it a stone of both intellectual and material well-being. Its brilliant sparkle is thought to mirror the clarity of thought it is said to inspire.
Blue Topaz is often connected to communication, creativity, and emotional balance. Its cool blue color is associated with calmness and serenity, and it is believed to help soothe stress and anxiety. Some metaphysical traditions suggest that blue topaz can aid in expressing oneself clearly and truthfully, making it a stone for artists, writers, and public speakers.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of any gemstone jewelry. The varying hardness and stability of December's birthstones require specific attention.
Turquoise, with its relatively low hardness and porous nature, is the most delicate of the four. It should be protected from harsh chemicals, perfumes, and cosmetics, which can damage or discolor the stone. Cleaning should be done with a soft, damp cloth; avoid ultrasonic cleaners, steam cleaners, and harsh soaps. It is best to store turquoise jewelry separately to prevent scratching by harder stones.
Tanzanite is moderately hard but can be brittle due to its cleavage properties. It should be protected from sharp blows and extreme temperature changes. Cleaning can be done with warm water, a mild soap, and a soft brush. Avoid ultrasonic cleaners and sudden temperature changes, which could cause cracking. It is also advisable to remove tanzanite jewelry during vigorous activities.
Blue Zircon is relatively hard and durable but can be brittle. It is generally safe for everyday wear but should be protected from hard impacts. Cleaning is straightforward: use warm soapy water and a soft brush. Avoid harsh chemicals and ultrasonic cleaners, especially if the stone has inclusions or fractures. Due to its high refractive index, it can show dirt and oils more readily, so regular gentle cleaning is recommended.
Blue Topaz, being hard and durable, is well-suited for regular wear. It can be cleaned with warm soapy water and a soft brush. Ultrasonic cleaners are generally safe, but steam cleaning should be avoided due to the potential for thermal shock. As with all gemstones, it is wise to avoid exposing blue topaz to sudden temperature changes and harsh chemicals to preserve its color and integrity.
Conclusion
December's four birthstones—Turquoise, Tanzanite, Blue Zircon, and Blue Topaz—offer a remarkable range of colors, histories, and properties. From the ancient, earthy allure of Turquoise to the modern, transformative vibrancy of Tanzanite, each stone provides a unique connection to the winter season. Their diverse origins, from single-source Tanzanite to globally sourced Topaz and Zircon, reflect the vast geological diversity of our planet. While their gemological properties vary significantly, from the soft, matrix-rich Turquoise to the hard, brilliant Blue Topaz, all share a symbolic resonance with clarity, protection, and calmness. For those born in December, this abundance of choice allows for a personal selection that aligns with individual style, lifestyle, and the meanings they wish to carry. Whether chosen for its historical significance, metaphysical beliefs, or simply its captivating beauty, any of these four gemstones serves as a meaningful and cherished emblem of the final month of the year.