December is a unique month in the gemological calendar, distinguished by its allowance of four distinct and officially recognized birthstones. Unlike months that are tied to a single gem, December offers a palette of cool, icy, and profound blues that perfectly mirror the winter season. The four birthstones—Turquoise, Tanzanite, Zircon, and Blue Topaz—provide a remarkable spectrum of color, history, and scientific properties. From the ancient, opaque charm of Turquoise to the modern, pleochroic brilliance of Tanzanite, these gems represent a fascinating intersection of geological rarity, human history, and personal expression. This article provides a comprehensive exploration of each of these four magnificent stones, detailing their unique stories, gemological characteristics, and the lore that has made them cherished symbols for those born in the final month of the year.
A Tapestry of History and Lore
The history of December’s birthstones is as diverse as the gems themselves, spanning millennia and continents. Each stone carries a legacy steeped in mythology, royalty, and spiritual belief, reflecting the cultures that first unearthed and revered them.
Turquoise: The Ancient Talisman
Turquoise is arguably the most historically significant of the four, with a lineage that stretches back thousands of years. Its name is derived from the French phrase pierre turquoise, meaning "Turkish stone," as it was first brought to Europe through Turkey, though it was originally mined in Persia (modern-day Iran). This semi-translucent to opaque gem, ranging in color from sky blue to green, has been a universal symbol of protection and wisdom. The pharaohs and other rulers of ancient Egypt adorned themselves with it, and Chinese artisans were carving it more than 3,000 years ago.
Throughout history, Turquoise was believed to possess potent beneficial powers. It was thought to guarantee health, good fortune, and protection from harm. From the 13th century onward, a specific superstition held that the stone would protect the wearer from falling, particularly from a horse, and would shatter at the approach of disaster to warn its owner. In Hindu mysticism, it was believed that seeing a turquoise after beholding the new moon would ensure fantastic wealth. For Native American cultures, particularly the Apache, the stone held deep spiritual significance; they believed turquoise could be found by following a rainbow to its end and that it offered a connection to the sky and water.
Tanzanite: The Modern Marvel
In stark contrast to Turquoise’s ancient origins, Tanzanite is a distinctly modern gem. It was discovered as recently as 1967 in the Merelani foothills of Mount Kilimanjaro in Tanzania. This velvety blue-violet stone is remarkable for its trichroic properties, meaning it can display three different colors—deep blue, violet, and reddish-brown—depending on the crystal axis and viewing angle. Its discovery is a 20th-century story, and its rapid ascent to prominence was fueled by its unique color and the marketing power of Tiffany & Co., which introduced it to the world in 1968 and named it after its country of origin. Despite its recent discovery, it has quickly become a beloved symbol of luxury and transformation.
Zircon: The Stone of Brilliance and Confusion
Zircon has a long history, though it is often confused with the synthetic cubic zirconia, a much more recent invention. For centuries, Zircon was a prominent gem in the Middle Ages, believed to bring wisdom, wealth, and protection. It was also said to promote honor and purity in its wearer. Its high refractive index and strong dispersion (fire) made it a popular diamond simulant for centuries. The confusion between Zircon and cubic zirconia has unfortunately overshadowed its historical significance, but for gem enthusiasts, natural Zircon remains a prized stone for its exceptional brilliance and range of colors, most notably the vibrant blue hues favored for December.
Blue Topaz: The Modern Classic
Blue Topaz has become one of the most popular and accessible blue gemstones in the modern market. While Topaz as a mineral occurs in many colors, the serene blue varieties have become a staple for December birthdays. Its journey to becoming a birthstone is more recent, reflecting evolving trends in the gemstone market. It is valued for its brilliant sparkle, clarity, and wide range of blue shades, from the palest sky blue to the deep, saturated tones of Swiss or London Blue Topaz. Its symbolism is tied to calmness, communication, and emotional balance, making it a meaningful and beautiful choice for contemporary jewelry.
Geological Formation and Global Sources
The origins of these four gems are as varied as their appearances. Each formed under unique geological conditions, and their sources are concentrated in specific, often rare, locations around the globe.
Turquoise is a secondary mineral that forms in arid regions where acidic, copper-rich groundwater percolates through aluminum- and phosphorus-rich rocks. This process occurs over millions of years, depositing the turquoise in veins and nodules. The most significant sources include the southwestern United States (Arizona, New Mexico, Nevada), Iran, Egypt, China, Mexico, and parts of Central Asia and Africa. The presence of a "matrix"—the remnants of the host rock—creates the unique spiderweb patterns seen in many turquoise specimens.
Tanzanite is a variety of the mineral zoisite and is found in only one location on Earth: the Merelani mining area near Mount Kilimanjaro in Tanzania. Its formation is linked to a unique geological event where the tectonic plates shifted and metamorphosed the host rock, allowing the necessary elements to combine under specific temperature and pressure conditions. This extreme rarity of location contributes significantly to its value and allure.
Zircon is one of the oldest minerals on Earth, found in the crust of every continent. It forms in igneous and metamorphic rocks. While it is mined in many countries, including Australia, Sri Lanka, and the United States, the highly prized blue zircon is most often created by heat-treating brown zircon from Cambodia, Thailand, or Vietnam. The heat treatment, which turns the stone a vivid blue, is a standard industry practice.
Blue Topaz is a crystalline mineral that forms in igneous rocks, particularly in pegmatites and high-temperature veins. While natural blue topaz does exist, the vast majority of the vivid blue topaz seen in the market is the result of irradiation and heat treatment of colorless or pale topaz. Major sources of the raw material include Brazil, Nigeria, and Sri Lanka, with the stones often being treated in the United States or other countries with advanced gemological facilities.
Gemological Properties: A Scientific Profile
Understanding the physical and chemical properties of these gemstones is crucial for gemologists, jewelers, and consumers alike. These properties determine a stone’s durability, appearance, and care requirements.
| Gemstone | Chemical Composition | Hardness (Mohs Scale) | Refractive Index | Crystal System | Key Features |
|---|---|---|---|---|---|
| Turquoise | Hydrated phosphate of copper and aluminum | 5 - 6 | 1.61 - 1.65 | Triclinic | Opaque, often contains matrix (veins of host rock) |
| Tanzanite | Calcium aluminum silicate hydroxide | 6.5 - 7 | 1.69 - 1.70 | Orthorhombic | Strong trichroism (blue, violet, reddish-brown) |
| Zircon | Zirconium silicate | 6.5 - 7.5 | 1.92 - 2.01 | Tetragonal | High refractive index, strong dispersion ("fire") |
| Blue Topaz | Aluminum silicate fluoride hydroxide | 8 | 1.63 - 1.64 | Orthorhombic | Often treated for color, excellent clarity |
Turquoise is the softest of the four, with a hardness of 5 to 6 on the Mohs scale. Its opacity and porosity mean it is susceptible to chemicals, lotions, and even the oils from human skin, which can alter its color over time.
Tanzanite is slightly harder at 6.5 to 7, making it more durable than Turquoise but still requiring care. Its most defining characteristic is its strong pleochroism (specifically trichroism), where the stone displays different colors when viewed from different directions. Gem cutters must orient the crystal carefully to showcase the dominant blue-violet hue.
Zircon is harder, ranging from 6.5 to 7.5, but it is known for its brittleness and can be easily fractured if struck. Its exceptional refractive index of up to 2.01 gives it a brilliance that rivals diamond, and its high dispersion creates a dazzling play of colored light.
Blue Topaz is the hardest and most durable of the group, rating an 8 on the Mohs scale. This makes it an excellent choice for all types of jewelry, including rings that are subject to daily wear. It is typically found in large, clean crystals, allowing for the creation of sizable, eye-clean gemstones.
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, December’s birthstones are rich in symbolic meaning and are believed by many to possess metaphysical properties.
Turquoise remains a powerful symbol of protection, wisdom, tranquility, and friendship. It is widely believed to promote self-expression and compassion, acting as a calming and balancing stone for its wearer.
Tanzanite, as a relatively new stone, is associated with transformation, spiritual growth, and creativity. It is considered a stone of higher consciousness, intended to open the mind and guide one toward their true destiny.
Zircon is thought to enhance mental clarity, intuition, and grounding. Historically, it was believed to bring honor and purity to the wearer, and its brilliance is said to help clear negative energy.
Blue Topaz is linked to calmness, communication, and emotional balance. It is often called the "stone of love and good fortune" and is believed to aid in honest communication and the expression of feelings.
Care and Cleaning: Preserving Your Gem
Proper care is essential to maintain the beauty and integrity of any gemstone. Due to their varying hardness and stability, the December birthstones require different approaches to cleaning and storage.
Turquoise: As the most delicate of the four, Turquoise should be kept away from water, oils, lotions, and harsh chemicals, which can cause discoloration or surface damage. Clean it only with a soft, dry cloth. Store it separately from other jewelry to prevent scratches.
Tanzanite: This gem is sensitive to abrupt temperature changes and should never be exposed to sudden heat or cold. It is also relatively brittle, so it is best suited for pendants and earrings rather than rings that might receive hard knocks. Clean with warm, soapy water and a soft brush.
Zircon: While hard, Zircon is brittle. It should be protected from sharp blows. Cleaning can be done with warm, soapy water and a soft brush. Avoid ultrasonic cleaners and steam cleaning, as these can fracture the stone.
Blue Topaz: Thanks to its high hardness, Blue Topaz is quite durable and easy to care for. It can be safely cleaned in an ultrasonic cleaner or with warm, soapy water and a soft brush. However, it is important to note that some irradiated topaz may be sensitive to heat, so it is wise to consult a professional jeweler before using high-heat cleaning methods like steam.
Conclusion
The four birthstones of December—Turquoise, Tanzanite, Zircon, and Blue Topaz—offer an unparalleled variety for those celebrating a December birthday. They span a vast spectrum of color, from the earthy greens and blues of ancient Turquoise to the electric blues and violets of modern Tanzanite. Their histories are equally diverse, ranging from the protective talismans of pharaohs to the celebrated discovery of a single mine in Tanzania. With distinct gemological properties that dictate their durability and care, each stone presents a unique combination of beauty and character. Together, they form a collection that is not only visually stunning but also deeply meaningful, capturing the cool, enchanting spirit of winter and providing a lifetime of beauty and significance.