December is uniquely associated with a palette of cool-toned gemstones, offering a diverse selection for those born in the final month of the year. While many months claim a single birthstone, December stands out with its array of traditional and modern options: Turquoise, Tanzanite, Zircon, and Blue Topaz. These stones, ranging from the earthy, sky-blue hues of Turquoise to the vivid, shifting blues of Tanzanite and the brilliant fire of Zircon, provide a spectrum of choices for jewelry enthusiasts and gift-givers alike. This article delves into the history, geological origins, gemological properties, and cultural significance of each of these December birthstones, providing a comprehensive guide for gemstone aficionados and those born under the signs of Sagittarius and Capricorn.
History and Lore of December's Gems
The tradition of birthstones is ancient, with roots tracing back to civilizations that attributed mystical and healing properties to specific gems. For December, the historical narrative is rich and varied, with each stone carrying its own legacy.
Turquoise, one of the oldest known gemstones, has been cherished for millennia. According to historical accounts, it was used by the pharaohs and other rulers of ancient Egypt for adornment. Chinese artisans were carving Turquoise more than 3,000 years ago, indicating its long-standing value in Eastern cultures. The stone’s name is believed to derive from the French phrase "pierre tourques," meaning "Turkish stone," reflecting its historical trade route from Persia through Turkey to Europe. In many cultures, Turquoise is considered a sacred stone. Native American tribes, such as the Apache, held beliefs that Turquoise could be found by following a rainbow to its end. The stone was also thought to possess protective powers; from the 13th century onward, it was believed to safeguard the wearer from falls, particularly from horses, and would break into pieces as a warning of impending disaster. Hindu mystics maintained that seeing a Turquoise after beholding the new moon ensured fantastic wealth. Its traditional symbolism is deeply tied to friendship, protection, and good fortune.
Tanzanite is a relatively modern addition to the gemstone world. It was first discovered in the 1960s in a single small area in the Merelani Hills of Tanzania, making it one of the rarest gemstones on Earth. Its discovery is often linked to a bushfire in 1967 that revealed its vivid blue color to local herders. The gem was later introduced to the international market by the jewelry company Tiffany & Co., which recognized its unique beauty and named it after its country of origin. While it lacks the ancient lore of Turquoise, Tanzanite has quickly accumulated modern symbolism. It is often associated with transformation, new beginnings, and a sense of clarity, making it a meaningful stone for those embarking on new chapters in life.
Zircon is one of the oldest minerals on Earth, with zircon crystals found in Australia dating back over 4.4 billion years. The name "zircon" may come from the Arabic "zarkun," meaning "vermillion" or "golden," or the Persian "zargun," meaning "gold-colored." Historically, colorless Zircon was a popular diamond simulant in the 19th century due to its high refractive index and brilliance. In the Middle Ages, Zircon was believed to promote honor, purity, and wisdom, and to ensure a restful sleep. It was also thought to ward off evil spirits and protect against lightning. As a December birthstone, it is linked to clarity, wisdom, and a sense of balance.
Blue Topaz, while not a traditional December birthstone, has become a popular modern alternative, especially in the United States. The word "topaz" is believed to originate from the Sanskrit word "tapas," meaning fire, or the Greek "Topazios," the ancient name of an island in the Red Sea where the gemstone was said to be found (though the stones from this island were later identified as Peridot). Historically, topaz was associated with strength and protection. In modern times, Blue Topaz has come to symbolize love, fidelity, and calmness, making it a favored choice for romantic gifts.
Geological Formation and Mining Locations
Each of December's birthstones forms under distinct geological conditions, resulting in unique appearances and mining locations.
Turquoise is a phosphate mineral that forms in arid regions where acidic, copper-rich groundwater seeps through rocks containing aluminum and phosphorus. Over thousands of years, the minerals crystallize into veins or nodules. Major sources include Iran (historically the most prized), the United States (particularly Arizona and New Mexico), Tibet, and India. American Turquoise often contains a "matrix," or remnants of the host rock, which creates distinctive web-like patterns within the stone.
Tanzanite is a variety of the mineral zoisite and owes its blue color to the presence of vanadium. It forms in a single, small geological area in the Merelani Hills of northern Tanzania, near the base of Mount Kilimanjaro. This geographic limitation makes Tanzanite exceptionally rare, as it is believed that the specific conditions required for its formation have only occurred in this one location in the entire world.
Zircon is a zirconium silicate mineral that forms in igneous and metamorphic rocks. It is commonly found in Sri Lanka, Cambodia, Australia, and Norway. Australian Zircon is particularly notable for its age, with some crystals dating back to the Hadean Eon. Zircon is often recovered as a byproduct of mining other minerals, such as tin and gold.
Blue Topaz is a silicate mineral that forms in pegmatites and hydrothermal veins. While natural blue topaz is extremely rare, the vast majority of blue topaz on the market is created by irradiating and heat-treating colorless topaz. Major sources for the raw material include Brazil, Nigeria, and Sri Lanka. The United States, particularly Texas (where it is the state gem), Utah, and California, also has deposits of topaz, though much of the commercial blue topaz is processed from stones mined elsewhere.
Gemological Properties: A Comparative Analysis
Understanding the physical and optical properties of these gemstones is crucial for both collectors and jewelers, as it influences their durability, care, and value. The following table compares key gemological properties based on the provided sources.
| Property | Tanzanite | Turquoise | Zircon | Blue Topaz |
|---|---|---|---|---|
| Mineral Group | Zoisite | Phosphate | Zirconium Silicate | Silicate |
| Chemical Formula | Ca₂(Al,OH)₂(SiO₄) | CuAl₆(PO₄)₄(OH)₈·4H₂O | ZrSiO₄ | Al₂SiO₄(F,OH)₂ |
| Mohs Hardness | 6 to 7 | 5 to 6 | 6.5 to 7.5 | 8 |
| Crystal System | Orthorhombic | Triclinic | Tetragonal | Orthorhombic |
| Refractive Index | 1.691 – 1.700 | 1.610 – 1.650 | 1.92 – 2.01 | 1.609 – 1.627 |
| Specific Gravity | 3.35 | 2.6 – 2.9 | 4.6 – 4.7 | 3.53 |
| Typical Treatments | Heat (to enhance blue color) | Stabilization (impregnation with resin/wax) | Heat (to improve color and clarity), Radiation | Irradiation and Heat (to produce blue color) |
| Common Colors | Blue to violet, often with pleochroism (showing different colors from different angles) | Sky blue to greenish-blue, often with matrix (veining) | Colorless, blue, yellow, brown, green; blue is most valued for December | Pale blue to deep "London Blue" |
| Cleavage | Imperfect | None | Poor | Good |
Tanzanite has a hardness of 6 to 7 on the Mohs scale, making it moderately durable but susceptible to chipping due to its cleavage. Its most distinctive feature is its strong pleochroism, showing blue, violet, and reddish hues from different crystal directions. This is why it is typically cut with the table facing the blue direction to maximize its signature color. Heat treatment is standard to transform the brownish zoisite into the desirable blue-violet variety.
Turquoise is relatively soft, with a hardness of only 5 to 6, making it porous and susceptible to damage from chemicals, cosmetics, and prolonged exposure to sunlight or heat. Most commercial Turquoise is stabilized—impregnated with a clear resin or wax—to enhance its durability, color, and polish. Natural, untreated Turquoise is rare and highly prized. Its color ranges from sky blue to greenish-blue, and the presence of matrix (the host rock) is a common characteristic, especially in American varieties.
Zircon is notably brilliant due to its high refractive index (1.92–2.01), which is higher than that of diamond. It also has strong dispersion, giving it exceptional fire (flashes of spectral color). However, Zircon is brittle and can chip along its cleavage planes, making it less suitable for rings unless set in protective settings. Most blue Zircon on the market is heat-treated from brown or yellow crystals, a process that is generally stable.
Blue Topaz is one of the hardest of the December stones, with a Mohs hardness of 8, making it highly durable and suitable for everyday wear in rings and bracelets. It is also relatively tough and resistant to cleavage. Nearly all blue topaz is treated; natural blue topaz is exceedingly rare. The treatment involves irradiation followed by heat, which creates the stable blue colors ranging from pale sky blue to deep London Blue. Topaz is also sensitive to sharp impacts, so care should be taken to avoid knocks.
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, these gemstones are imbued with symbolic meanings and metaphysical properties, which have evolved over centuries.
Turquoise is universally regarded as a stone of protection, truth, and calmness. Its association with friendship and good fortune makes it a popular gift. In spiritual practices, it is believed to align all chakras, promote inner peace, and shield the wearer from negative energy. Its connection to the sky and water elements in various cultures reinforces its symbolism of tranquility and healing.
Tanzanite, as a modern gem, symbolizes transformation, intuition, and spiritual awakening. It is often called the "stone of magic" and is believed to facilitate communication with higher spiritual realms. Its unique color, which can appear to shift, is seen as a metaphor for the multifaceted nature of reality and personal growth. It is particularly associated with the throat and third-eye chakras, aiding in clear communication and psychic awareness.
Zircon has long been associated with wisdom, honor, and purity. It is believed to promote self-confidence, increase willpower, and bring prosperity. In crystal healing, Zircon is said to help with sleep and dreams, warding off nightmares. Its brilliant sparkle is linked to clarity of thought and emotional balance, making it a stone for those seeking stability and insight.
Blue Topaz is considered a stone of love, fidelity, and calm communication. It is associated with the throat chakra, helping to express feelings and thoughts clearly and honestly. Its serene blue color is linked to mental clarity, reducing stress and anxiety. It is also believed to promote relaxation and peaceful sleep, making it a soothing companion for meditation and introspection.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of these gemstones, and it varies significantly based on their physical properties.
Turquoise requires the most delicate handling. With a hardness of only 5 to 6 and porosity, it should be protected from chemicals, perfumes, lotions, and prolonged exposure to sunlight or heat, which can cause discoloration. Clean Turquoise jewelry with warm, soapy water and a soft cloth. Avoid ultrasonic cleaners, steam, and harsh chemicals. It is best to store Turquoise separately to prevent scratches.
Tanzanite, with a hardness of 6 to 7, is moderately durable but is prone to chipping due to its cleavage. It should be protected from sharp blows and extreme temperature changes. Clean Tanzanite with warm, soapy water and a soft brush. Avoid ultrasonic and steam cleaners, as they can cause fractures. It is recommended to remove Tanzanite jewelry during physical activities.
Zircon is brittle and can be damaged by sharp impacts. While it has a high hardness, its cleavage planes make it vulnerable. Avoid ultrasonic cleaners and steam, as these can cause cracking. The best cleaning method is warm, soapy water and a soft brush. Store Zircon jewelry carefully to prevent chips, especially in rings.
Blue Topaz, with a hardness of 8, is the most durable of the common December stones. It is suitable for everyday wear but can be sensitive to sharp impacts. Clean it with warm, soapy water and a soft brush. It is generally safe for ultrasonic cleaners, but it is advisable to check with a jeweler first, especially if the stone has fractures. Avoid sudden temperature changes and harsh chemicals.
Conclusion
December's birthstones offer a remarkable diversity in color, history, and meaning. From the ancient, protective Turquoise to the rare and transformative Tanzanite, the wise and brilliant Zircon, and the durable, loving Blue Topaz, each gemstone provides a unique connection to the month. Their varying gemological properties dictate their care and suitability for different types of jewelry, while their rich histories and symbolic meanings add layers of significance. For those born in December, the choice of a birthstone is not merely aesthetic but a personal connection to a legacy of beauty, science, and culture. Whether selected for its spiritual properties, historical allure, or simply its captivating hue, a December birthstone is a timeless and meaningful treasure.