December occupies a unique place in the birthstone calendar, distinguished as the only month officially associated with four distinct gemstones. This multiplicity offers a remarkable range of colors and characteristics, all unified by a cool, wintry palette that reflects the season's icy skies and deep twilight blues. The four recognized December birthstones are Tanzanite, Turquoise, Blue Zircon, and Blue Topaz. Each possesses a unique geological origin, a rich tapestry of history, and distinct symbolic meanings, providing a diverse selection for jewelry enthusiasts and those seeking a personal connection to their birth month.
The tradition of assigning gemstones to specific months has ancient roots, believed to have originated in Mesopotamia and later adopted by the Greeks and Romans. The December birthstone list has evolved significantly over time. Originally, only Turquoise and Zircon were considered December’s gems. The 20th century saw expansions to the list, with Blue Topaz and, most recently, Tanzanite (added in 2002) being incorporated. This evolution reflects both the growing appreciation for new gemstone discoveries and the commercial appeal of offering variety in color, availability, and cost. While Turquoise is often cited as the traditional and most timeless choice, the modern list embraces a spectrum of blue hues, from the soft sky blue of turquoise to the rich, shifting violet-blue of tanzanite. This article will explore the history, geology, gemological properties, and symbolism of each of these four remarkable stones, providing a comprehensive guide for gemstone enthusiasts, jewelry buyers, and students of gemology.
Historical Lore and the Path to Modern Birthstone Status
The journey of these gemstones from ancient artifacts to modern birthstones is a story of cultural significance and evolving tradition.
Turquoise stands as the oldest member of the December quartet, with a history spanning over 5,000 years. Ancient miners first discovered it in Egypt’s Sinai Peninsula, where it was carved into jewelry, amulets, and ornaments for the pharaohs. Its presence is famously immortalized in the death mask of Tutankhamun, where turquoise details still shine after millennia. In Persia (modern-day Iran), turquoise represented the color of the heavens. Persian kings adorned their palaces with turquoise tiles, believing the stone brought victory, good fortune, and a connection to the sky. Traders later carried the stone along the Silk Road to Europe, where it became known as “Turkish stone.” Across the Atlantic, Native American tribes such as the Navajo, Zuni, and Pueblo peoples also valued turquoise deeply, seeing it as a sacred gift from the sky.
Zircon is one of the original December birthstones. Its history is long and often confused due to its frequent mistaken identity with diamond, a confusion born from its exceptional brilliance and fire. For centuries, zircon was prized not only for its beauty but also for its perceived protective qualities. It was often used as a talisman for travelers, believed to ward off evil spirits and promote restful sleep. Its inclusion in the 1912 list by the National Association of Jewelers solidified its status, and it was later confirmed in the 1952 update by the Jewelry Industry Council of America.
Blue Topaz has a more ambiguous historical origin, having been found throughout history, but its specific connection to December is a modern development. Its path to becoming a birthstone was largely commercial. The 1912 standardization by the National Association of Jewelers was a practical move to combine customs with gemstones that would be commercially viable for jewelry companies. Blue Topaz, with its attractive blue color and increasing availability, gained popularity and was formally added to the December list in the 1952 update.
Tanzanite is the most recent addition, officially recognized as a December birthstone in 2002. Its story is entirely modern, a tale of a recent geological discovery that captured the gemological world's imagination. Its addition reflects the tradition's ability to evolve, embracing new and captivating gemstones that resonate with contemporary tastes. Despite its newness, it has quickly become one of the most valued and sought-after of the December stones.
Geological Formation and Sources
Understanding where these gemstones come from adds a layer of appreciation for their rarity and beauty.
Turquoise is a hydrated phosphate mineral containing copper and aluminum. Its characteristic blue-green color comes from the presence of copper. It forms in arid regions where acidic, copper-rich groundwater percolates through aluminum-bearing rocks. The most significant historical sources are in Egypt’s Sinai Peninsula and Persia (Iran). Modern sources include the southwestern United States (Arizona, New Mexico, Nevada), China, and Tibet. Each location can impart slightly different characteristics to the stone, such as matrix patterns (the host rock within the turquoise).
Zircon is a zirconium silicate mineral and is one of the oldest minerals on Earth, often found in igneous and metamorphic rocks. While it occurs worldwide, the gem-quality blue zircon used in jewelry is primarily sourced from Cambodia, Sri Lanka, and Australia. The blue color in zircon is typically the result of heat treatment applied to brownish zircon crystals, a process that can also improve clarity.
Blue Topaz is a silicate mineral of aluminum and fluorine. Natural blue topaz is exceptionally rare; most of the vibrant blue topaz on the market is the product of treating colorless or pale blue topaz with heat and irradiation. The major commercial sources for the raw material include Sri Lanka, Brazil, Mexico, Nigeria, and the United States. In the U.S., blue topaz is notably found in Texas, Utah, and California, and it holds the distinction of being the official state gem of Texas.
Tanzanite is the trade name for the blue-violet variety of the mineral zoisite. Its geological formation is exceptionally unique. It is found in only one place on Earth: a small, four-square-kilometer mining area in the Merelani Hills of northern Tanzania, near the base of Mount Kilimanjaro. This extreme geographic limitation makes tanzanite significantly rarer than diamond. The stones are formed through a complex geological process involving intense heat and pressure, which is believed to have occurred during the formation of the East African Rift Valley millions of years ago.
Gemological Properties
A scientific examination reveals the distinct physical and chemical characteristics of each December stone.
| Gemstone | Chemical Formula | Mohs Hardness | Crystal System | Refractive Index | Key Characteristics |
|---|---|---|---|---|---|
| Turquoise | CuAl₆(PO₄)₄(OH)₈·4H₂O | 5 - 6 | Triclinic | 1.61 - 1.65 | Porous, often contains matrix (host rock). Color ranges from sky blue to greenish blue. |
| Zircon | ZrSiO₄ | 6.5 - 7.5 | Tetragonal | 1.92 - 2.01 | High refractive index and strong dispersion ("fire"). Often heat-treated to achieve blue color. |
| Blue Topaz | Al₂SiO₄(F,OH)₂ | 8 | Orthorhombic | 1.609 - 1.627 | Most durable of the December stones. Most blue color is from treatment of colorless topaz. |
| Tanzanite | Ca₂Al₃(SiO₄)₃(OH) | 6 - 6.5 | Orthorhombic | 1.691 - 1.700 | Pleochroic (shows different colors: blue, violet, burgundy). Often heat-treated to enhance blue color. |
Turquoise is the softest of the group (Mohs 5-6) and is porous, making it susceptible to damage from chemicals, heat, and prolonged exposure to skin oils and lotions. Its color can fade if exposed to intense light or heat. High-quality turquoise is valued for its even color and minimal matrix.
Zircon is notably brilliant due to its high refractive index and strong dispersion, which gives it exceptional "fire" that can rival a diamond's. With a Mohs hardness of 6.5 to 7.5, it is reasonably durable but can be brittle due to its crystal structure. The blue color is almost always a result of heat treatment, which can also improve clarity.
Blue Topaz is the most durable of the four December birthstones for everyday wear. With a Mohs hardness of 8, it is resistant to scratching and abrasion, making it an excellent choice for rings and bracelets. The vast majority of blue topaz on the market is treated; natural blue topaz in significant sizes is exceedingly rare.
Tanzanite has a Mohs hardness of 6 to 6.5, making it softer than topaz and zircon and more suitable for earrings and pendants than for rings subject to daily wear. Its most captivating gemological property is its strong pleochroism—the ability to show different colors when viewed from different crystal directions. A tanzanite crystal might appear blue from one angle, violet from another, and burgundy-red from a third. Most tanzanite is heat-treated to remove the brownish-red component and enhance the desirable blue-violet hue.
Symbolism and Metaphysical Beliefs
Across cultures and centuries, these gemstones have been imbued with profound meanings.
Turquoise is universally associated with protection, good fortune, and peace. Ancient Egyptians believed it offered protection from harm, while Persians associated it with victory and divine connection. For Native American cultures, it is a sacred stone symbolizing the sky and water. Modern interpretations often link turquoise to grounding, emotional balance, and calming chaotic energies.
Zircon has long been associated with clarity, wisdom, and balance. It was traditionally believed to aid in sleep, promote honor, and bring prosperity. Its brilliant sparkle is thought to stimulate energy and enthusiasm. As a birthstone, it symbolizes a clear mind and a balanced spirit.
Blue Topaz is often linked to love, fidelity, and calm communication. Its serene blue color evokes feelings of tranquility and peace. In modern crystal healing practices, it is associated with the throat chakra, promoting honest and clear expression. It is also believed to soothe tempers and reduce stress.
Tanzanite, as the newest member, has quickly developed its own symbolism centered on transformation, intuition, and new beginnings. Its unique discovery story and striking color shift are seen as metaphors for personal growth and spiritual awakening. It is often described as a stone of higher consciousness, encouraging a connection to one's destiny and higher purpose.
Care and Cleaning Recommendations
Proper care is essential to maintain the beauty and longevity of these gemstones, with recommendations varying significantly based on their physical properties.
Turquoise requires the most careful handling due to its porosity and softness. It should be cleaned with a soft, dry cloth. Avoid ultrasonic cleaners, steam cleaners, and any chemical cleaners, including soaps and lotions, which can be absorbed and cause discoloration or damage. Store it separately to avoid scratches from harder stones.
Zircon is relatively durable but can be brittle. It is safe to clean with warm soapy water and a soft brush. Avoid ultrasonic cleaners and sudden temperature changes, which can cause fractures. Its hardness makes it suitable for most jewelry settings, but care should be taken to avoid hard blows.
Blue Topaz, being the hardest of the group, is the most resilient. It can be cleaned with warm soapy water, a soft brush, and an ultrasonic cleaner (unless the stone has fractures or inclusions). However, as most blue topaz is treated, it is advisable to avoid prolonged exposure to intense heat or radiation, which could potentially alter the color.
Tanzanite is softer and more fragile, making it best suited for protective settings like bezels. Clean it gently with warm soapy water and a soft brush. Avoid ultrasonic cleaners, steam cleaning, and harsh chemicals. Due to its cleavage (a tendency to break along flat planes), it should be protected from sharp blows and extreme temperature changes.
Conclusion
The four December birthstones—Tanzanite, Turquoise, Blue Zircon, and Blue Topaz—offer a remarkable diversity within a unified color scheme. From the ancient, protective heritage of Turquoise to the modern, transformative allure of Tanzanite, each stone carries a unique narrative. Their geological origins span the globe, from the arid deserts of the American Southwest to the single, precious mining area in Tanzania. Their gemological properties range from the soft, porous turquoise to the exceptionally hard and durable blue topaz. Whether chosen for its historical significance, symbolic meaning, or sheer aesthetic beauty, any of these four gemstones provides a meaningful and beautiful connection to the month of December, capturing the essence of winter's cool, serene beauty.