December is a unique month in the gemological calendar, distinguished by its association with not one, but three—and often four—distinct birthstones. This abundance offers those born in the winter month a rich palette of colors and properties to choose from. The primary birthstones recognized for December are Tanzanite, Turquoise, and Zircon, with Blue Topaz frequently included in modern lists. These gemstones, ranging from the ancient sky-blue of Turquoise to the vivid violet-blue of Tanzanite and the brilliant fire of Zircon, are united by their captivating blue hues, which are said to reflect the cool clarity of the winter season. Each stone carries a unique narrative, encompassing geological rarity, historical lore, and specific gemological characteristics that make them prized possessions for collectors and jewelry enthusiasts alike.
The selection of these specific gemstones is not arbitrary. It is the result of an evolving historical process, driven by both tradition and the practical needs of the jewelry trade. While some months are tied to a single, anciently revered stone, December’s list has expanded over time to include both traditional and modern additions. This guide will explore the distinct identity of each of December’s key birthstones—Tanzanite, Turquoise, and Zircon—delving into their geological origins, their journey through human history, their scientific properties, and the symbolic meanings that have been ascribed to them across cultures. We will also provide practical advice on the care and cleaning of these valuable minerals, ensuring their beauty endures for generations.
History and Lore
The history of December’s birthstones is a fascinating blend of ancient tradition and modern discovery. Turquoise, in particular, stands as one of the oldest known gemstones, with a history that spans millennia and continents. This semi-translucent to opaque gem, known for its distinctive blue-to-green coloration and often veined with a dark matrix, has been cherished by numerous civilizations. The pharaohs and elite of ancient Egypt adorned themselves with turquoise jewelry, valuing it not only for its beauty but also for its perceived protective powers. In China, artisans were carving turquoise into intricate objects more than 3,000 years ago, demonstrating its early cultural significance.
The lore surrounding Turquoise is rich with beliefs about its beneficial powers. It was widely thought to guarantee health and good fortune. A particularly enduring European belief, dating from the 13th century, held that the stone could protect the wearer from falls, particularly from horses, and would sacrifice itself by shattering in the face of impending disaster. Hindu mystics believed that gazing upon a turquoise after seeing the new moon would ensure immense wealth. In the Americas, the stone was equally revered; the Apache people believed turquoise could be found by following a rainbow to its end, linking the gem to celestial phenomena and promise.
Zircon is another of the Earth’s oldest minerals, with a history that predates many of the gemstones we know today. While it is often confused with the synthetic cubic zirconia, natural zircon has been a prized gem for centuries. In the Middle Ages, zircon was believed to induce sound sleep, ward off evil spirits, and promote prosperity and honor. Its brilliance and fire led to its association with wisdom and clarity of thought. Throughout history, zircon has been a popular decorative stone, often used in religious and ceremonial objects, as well as in jewelry for royalty and the wealthy.
In stark contrast to its ancient counterparts, Tanzanite is a thoroughly modern gemstone. It was not discovered until the 1960s, making it a relative newcomer to the world of fine gems. Its discovery near the majestic Mount Kilimanjaro in Tanzania, East Africa, was a significant geological event. The stone’s vibrant blue-violet hues, characterized by a unique trichroism (the ability to show three different colors—blue, violet, and redish-purple—from different crystallographic directions), immediately captured the attention of the global jewelry market. Its rapid rise to prominence was fueled by a major international jewelry house, which helped establish it as a premier gemstone. Its addition to the official birthstone list in 2002 solidified its status as a modern classic, representing transformation and new beginnings for those born in December.
The list of December’s birthstones has seen official revisions over the years, reflecting changes in gemstone availability and consumer preference. The modern standardization of birthstones began in 1912 with the National Association of Jewelers, which sought to create a practical list for the trade. In 1952, the Jewelry Industry Council of America updated the list, adding Zircon to December’s offerings. The most recent significant addition was Tanzanite in 2002. Blue Topaz is also frequently cited as a December birthstone, though it is more of a modern commercial addition than a traditional one. The inclusion of multiple stones provides greater choice in terms of color, price, and durability, a key reason why December stands apart.
Geological Formation and Sources
Understanding the geological origins of these gemstones reveals why they possess such different properties and appearances. Each is formed under unique conditions and is found in only specific regions of the world, which contributes significantly to its rarity and value.
Tanzanite: Tanzanite’s origin story is as unique as the stone itself. It is a variety of the mineral zoisite and owes its stunning blue-violet color to trace amounts of vanadium within its crystal structure. The conditions required for its formation were exceptionally rare, occurring only once in geological history. It is found in a small, four-square-kilometer mining area in the Merelani Hills of Northern Tanzania, near the base of Mount Kilimanjaro. This extreme geographic limitation is the primary reason for its rarity; geologists theorize that the specific metamorphic event that created Tanzanite was an isolated occurrence, making it a true "gem of a single source."
Turquoise: Turquoise is an opaque, hydrous phosphate of copper and aluminum. Its formation is a secondary mineral, meaning it is not formed from magma but through the percolation of water through rocks rich in copper and aluminum. This process occurs in arid regions, where the water evaporates and leaves behind the turquoise deposits. Major sources for turquoise have historically been in the Persian Plateau (modern-day Iran), the Southwestern United States (Arizona, New Mexico, Nevada), and China. The distinctive blue and green colors come from the copper (blue) and iron (green) content of the host rock. The presence of a "matrix"—the web-like remnants of the host rock within the turquoise—is a common characteristic that affects the stone’s appearance and is often used to identify its geographic origin.
Zircon: Zircon (zirconium silicate, ZrSiO₄) is a mineral that occurs naturally in a wide range of colors, but the blue variety is most associated with December. It is found in igneous and metamorphic rocks worldwide and is one of the oldest minerals on Earth, with some crystals dating back billions of years. Zircon forms in the cooling of magma, and its high refractive index gives it exceptional brilliance and fire. Major sources for gem-quality zircon include Australia (which produces a wide range of colors, including the prized "hyacinth" red-orange variety), Cambodia, Sri Lanka, Thailand, and Myanmar. The blue color in zircon is typically achieved through a heat treatment process, which transforms the common brownish zircon into the desirable bright blue hue.
Blue Topaz (A Note on a Modern Addition): While not one of the three core stones in the provided texts, Blue Topaz is often mentioned as a fourth December birthstone. It is a silicate mineral containing fluorine and aluminum. Natural blue topaz is extremely rare; the vibrant blues seen in jewelry (such as Swiss Blue and London Blue) are the result of irradiation and heat treatment of colorless or pale topaz. Major sources for the raw topaz include Brazil, Sri Lanka, Nigeria, and the United States. Its inclusion in the list is primarily a modern commercial development, offering a very durable and affordable blue gemstone option.
Gemological Properties
For gemologists and buyers, the physical and optical properties of a gemstone are paramount. These characteristics determine not only its beauty and value but also its durability for use in jewelry. The December birthstones present a diverse range of properties.
Tanzanite: * Hardness: On the Mohs scale of hardness, Tanzanite ranks from 6 to 7. This makes it a moderately durable stone, but it is more susceptible to scratches and abrasions than harder gems like Sapphire or Diamond. It also possesses perfect cleavage in one direction, meaning it can be split with a sharp blow and requires careful handling and setting. * Color: Its most celebrated feature is its intense blue to violet color. It is strongly pleochroic, meaning it can display different colors (blue, violet, and a reddish-purple) when viewed from different crystal directions. Gem cutters must orient the stone carefully to display the most desirable blue-violet hue. * Clarity: Tanzanite is typically found with high clarity, often being "eye-clean." Inclusions are uncommon, which enhances its appeal. * Refractive Index: 1.690 – 1.700
Turquoise: * Hardness: Turquoise is relatively soft, ranking from 5 to 6 on the Mohs scale. This makes it unsuitable for rings that will be worn daily, as it is prone to scratching and can be damaged by chemicals, lotions, and even the natural oils of the skin. It is best suited for pendants, earrings, and other less-impactful jewelry forms. * Color: The color ranges from sky blue to blue-green and green, depending on the amount of copper (for blue) and iron (for green) present. The most prized color is an even, intense "robin's egg" blue. * Clarity: Turquoise is almost always opaque. Its matrix, the remnant of the host rock, is a key identifying feature and can appear in a variety of web-like patterns (e.g., black, brown, or yellow). * Specific Gravity: 2.60 – 2.90
Zircon: * Hardness: Zircon is the hardest of the three primary December stones, ranking from 6.5 to 7.5 on the Mohs scale. It is reasonably durable for most jewelry types, though it can be brittle due to its tetragonal crystal structure. * Color: While Zircon occurs in a rainbow of colors, the blue variety is the focus for December. As noted, most blue zircon is heat-treated from brownish crystals. The stone is renowned for its exceptional brilliance and fire, which can rival that of a diamond. * Clarity: Like Tanzanite, high-quality Zircon is typically eye-clean. * Refractive Index: 1.92 – 1.98 (This is very high, contributing to its exceptional brilliance).
The following table summarizes the key gemological properties of the three main December birthstones as detailed in the provided sources.
| Gemstone | Mohs Hardness | Chemical Composition | Key Characteristics | Primary Origin |
|---|---|---|---|---|
| Tanzanite | 6 – 7 | Ca₂Al₃(SiO₄)₃(OH) | Strong pleochroism (trichroism), perfect cleavage, vibrant blue-violet color. | Tanzania |
| Turquoise | 5 – 6 | CuAl₆(PO₄)₄(OH)₈·4H₂O | Opaque, often contains matrix, color ranges from blue to green. | Iran, SW USA, China |
| Zircon | 6.5 – 7.5 | ZrSiO₄ | High refractive index and fire, brittle, commonly heat-treated for blue color. | Australia, Cambodia, Sri Lanka |
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, the December birthstones are deeply imbued with symbolic meaning and metaphysical beliefs that have been passed down through generations. These associations add another layer of significance to the stones, connecting the wearer to ancient traditions and spiritual concepts.
Tanzanite: As a modern discovery, Tanzanite’s metaphysical lore is less ancient but has developed quickly. It is widely associated with transformation, intuition, and spiritual growth. It is believed to facilitate a higher consciousness and a clearer connection between the heart and the mind. For those born on December 16, sources suggest it can enhance loyalty, unity, and confidence, serving as a guide for spiritual journeys and a catalyst for new beginnings.
Turquoise: The symbolism of Turquoise is rooted in protection, healing, and good fortune. Historically, it was considered a sacred stone by many cultures, worn as a powerful talisman to ward off evil and protect the wearer from physical harm. It is also linked to friendship and positive energy, making it a popular gift to symbolize affection and well-being. Its association with health and fortune is a recurring theme across many traditions, from ancient Egypt to Native American beliefs.
Zircon: Zircon is traditionally associated with wisdom, clarity, prosperity, and honor. It is believed to help the wearer achieve a sense of balance and mental clarity, warding off negative energies and promoting self-confidence. Some traditions also attribute to it the power to induce sound sleep and bring prosperity to its owner. Its brilliant sparkle is seen as a reflection of inner light and wisdom.
Care and Cleaning
Proper care is essential to maintain the beauty and integrity of any gemstone, but it is especially critical for the December birthstones due to their varying levels of hardness and unique vulnerabilities. The following guidance is derived from expert gemological advice.
Tanzanite: Given its perfect cleavage and moderate hardness, Tanzanite requires careful handling. It should be protected from hard blows and extreme temperature changes, which can cause it to fracture. For cleaning, use warm water, a mild soap, and a soft brush. Avoid ultrasonic and steam cleaners, as the vibrations and heat can damage the stone. Store Tanzanite jewelry separately in a soft cloth or padded box to prevent scratching by other gems.
Turquoise: Turquoise is the most delicate of the group. Its porosity and low hardness make it susceptible to damage from chemicals, cosmetics, and even the natural oils of the skin, which can cause discoloration over time. It should be wiped clean with a soft, dry cloth after each wear. Avoid exposing it to water, lotions, or any harsh cleaning agents. Ultrasonic cleaners are strictly forbidden. Store it away from other jewelry to prevent scratching.
Zircon: While Zircon is relatively hard, it is brittle and can be chipped by a sharp impact. It is also sensitive to heat, which can alter its color. Cleaning should be done with warm soapy water and a soft brush. It is generally safe to use an ultrasonic cleaner for Zircon, but it is wise to be cautious, especially if the stone has any fractures. As noted in the sources, Zircon should not be exposed to direct sunlight for extended periods, as this can cause its color to fade. Store it in a separate compartment to protect it from being scratched by harder stones like diamonds or scratched by softer stones.
Conclusion
The birthstones of December—Tanzanite, Turquoise, and Zircon—offer a remarkable diversity of color, history, and character. From the ancient, protective talisman of Turquoise to the brilliant, wisdom-bearing Zircon and the transformative, modern allure of Tanzanite, each gem provides a unique connection to the natural world and human culture. Their geological origins, from the single-source mines of Tanzania to the widespread deposits of zircon and turquoise, speak to the Earth’s varied and wondrous processes. Their gemological properties, ranging from the soft, opaque beauty of turquoise to the fiery brilliance of zircon, dictate their use and care in jewelry. Ultimately, for those born in December, these stones are more than mere ornaments; they are symbols of protection, success, and inner strength, each carrying a rich story waiting to be told.