For those born in the twelfth month of the year, December offers a remarkable palette of gemstones that mirror the cool clarity of winter skies and the deep, serene hues of twilight. While the query for "December 15th birthstone color" points to a specific date, the tradition of December birthstones encompasses a trio of distinct yet harmonious gems: Turquoise, Tanzanite, and Zircon. Each stone carries a unique geological origin, a rich tapestry of historical lore, and a spectrum of color that has captivated humanity for millennia. This guide delves into the science, history, and symbolism of these three celebrated December birthstones, providing a comprehensive resource for gemstone enthusiasts, jewelry buyers, and students of gemology.
The modern list of December birthstones is not a singular entity but a curated collection of gems that share a common theme of cool, blue-dominated hues. According to the Gemological Institute of America (GIA), the primary December birthstones are Turquoise, Tanzanite, and Zircon. Over time, the list has expanded to include Blue Topaz, which has gained significant popularity, particularly in the United States. This expansion offers individuals born in December a wider range of choices in terms of color, durability, and price, allowing for a more personalized connection to their birthstone. The colors associated with these stones are predominantly blue, ranging from the sky blue of classic Turquoise to the vibrant violet-blue of Tanzanite and the icy pale blue of Zircon. This diversity ensures that every December-born individual can find a gem that resonates with their personal style and aesthetic.
History and Lore: A Journey Through Time
The concept of birthstones is ancient, with roots tracing back to civilizations that believed in the mystical and healing properties of gemstones. The tradition is often linked to the Breastplate of Aaron, a ceremonial garment described in the Old Testament, which was set with twelve different gemstones representing the twelve tribes of Israel. By the 1st century AD, Jewish historian Josephus made a connection between these twelve stones and the twelve signs of the zodiac, a concept later adopted by Christians in the 5th century who associated the stones with the twelve apostles. This early association laid the groundwork for the modern birthstone tradition, which assigns a specific gem to each month of the year.
Turquoise, as the traditional December birthstone, boasts one of the longest histories of any gem. Its use dates back over 6,000 years, with ancient Egyptian pharaohs adorning themselves with this semi-translucent to opaque blue-green stone. Chinese artisans were carving Turquoise more than 3,000 years ago. The stone’s name derives from the French "pierre turquoise," meaning "Turkish stone," as it was brought to Europe from Persia (modern-day Iran) via Turkey. Historically, Turquoise was believed to possess protective powers. From the 13th century onward, it was thought to safeguard the wearer from falls, particularly from horses, and would break into several pieces to signal an approaching disaster. Hindu mystics maintained that beholding a Turquoise after seeing the new moon would bring fantastic wealth. In Native American cultures, particularly among the Apache, Turquoise held deep spiritual significance; they believed it could be found by following a rainbow to its end, and it was used in ceremonies and as a talisman for protection and health.
Zircon, one of the oldest minerals on Earth, has been used in jewelry since the 4th century. Its name is likely derived from the Persian word "zargun," meaning "gold-colored," though Zircon is now most prized for its brilliant blue hues. For centuries, Blue Zircon was believed to possess properties of wisdom, honor, and purity. It was often used as a protective stone, said to bring prosperity and to drive away evil spirits. The stone’s high refractive index, which gives it a diamond-like sparkle, contributed to its mystique and value.
Tanzanite is a relative newcomer to the gemological world, discovered in the 20th century. Its story is one of modernity and serendipity. In 1967, a Masai herder in the Merelani Hills of northern Tanzania discovered a cluster of vivid blue crystals. Initially mistaken for Zircon, it was later identified by the New York-based gemologist Frederick Kunz as a new variety of the mineral zoisite. He named it "Tanzanite" after its country of origin. Its rapid rise to fame was fueled by the luxury jewelry company Tiffany & Co., which recognized its unique beauty and marketed it heavily in the 1960s and 1970s. While it lacks the ancient lore of Turquoise or Zircon, Tanzanite quickly acquired modern symbolism, often associated with transformation, clarity, and emotional healing.
Blue Topaz, while a popular modern alternative, also has ancient roots. The name "Topaz" comes from the Greek word "Topazios," the ancient name for an island in the Red Sea. Ironically, the gemstones found on that island were later identified as Peridot, not Topaz. Despite this, the name persisted. Natural Blue Topaz is rare, and most of the vivid blue stones on the market today are the result of treating colorless Topaz through irradiation and heat. This modern treatment process has made Blue Topaz an accessible and popular choice for December-born individuals seeking an affordable yet striking blue gem.
Geological Formation and Sources
Understanding the geological origins of these gems enhances their appreciation and reveals why they are found in specific, often limited, locations worldwide.
Turquoise is a hydrous phosphate of copper and aluminum. It forms in arid regions where acidic, copper-rich groundwater percolates through rocks containing aluminum and phosphorus minerals. Over millennia, this process creates nodules or veins of Turquoise within the host rock. The color ranges from sky blue to greenish-blue, primarily determined by the amount of copper (blue) or iron (green) present. The stone is often found with a "matrix," which is the remnants of the host rock (typically iron pyrite or sandstone) in which it formed, creating a webbed or spotted pattern. Major sources of high-quality Turquoise include Iran (Persian Turquoise), which historically produced the most prized sky-blue stones with little to no matrix. The United States is another significant source, with famous deposits in Nevada, Arizona, and New Mexico, producing stones with a wide range of colors and matrix patterns. Other notable sources include Tibet and India, where Turquoise is culturally significant and often used in traditional jewelry.
Tanzanite is a variety of the mineral zoisite, colored by vanadium. It is found in only one location on Earth: the Merelani Hills of Tanzania, near the base of Mount Kilimanjaro. This extreme rarity is a key factor in its value. The gem forms in the presence of intense heat and pressure, a process linked to the geological activity of the East African Rift Valley. The crystals are often elongated and can be heat-treated to enhance their blue color, a standard and permanent practice in the gem trade. Due to its single-source origin and the finite nature of the deposits, Tanzanite is considered one of the most precious gemstones of the 20th century.
Zircon is a zirconium silicate (ZrSiO₄) and is one of the oldest minerals on Earth, with some crystals dating back billions of years. It is found in many parts of the world, including Australia, which is the leading producer of gem-quality Zircon. Other significant sources include Cambodia, Myanmar, and Sri Lanka. Zircon forms in igneous and metamorphic rocks. The blue color in Blue Zircon is typically achieved through heat treatment of brownish Zircon crystals, a process that has been used since the 1920s. The treatment is stable and enhances the stone's color and brilliance. Unlike Tanzanite, Zircon is found in multiple locations, which helps ensure a more consistent supply, though the finest blue hues remain rare.
Blue Topaz is a variety of the mineral topaz, which is a fluorine aluminum silicate. It forms in igneous rocks, particularly in pegmatites and rhyolites. Natural blue topaz is exceedingly rare. The vast majority of Blue Topaz on the market is produced by irradiating colorless Topaz (often from Brazil, Nigeria, or Sri Lanka) and then heating it to achieve the desired shade of blue, ranging from pale "Sky Blue" to deeper "Swiss Blue" and "London Blue." This treatment is permanent and safe, making Blue Topaz a durable and affordable alternative.
Gemological Properties
The following table summarizes the key gemological properties of the three primary December birthstones, based on data from the provided sources.
| Property | Turquoise | Tanzanite | Zircon (Blue) |
|---|---|---|---|
| Mineral Group | Phosphate | Zoisite (a variety of Epidote group) | Zirconium Silicate |
| Chemical Formula | CuAl₆(PO₄)₄(OH)₈·4H₂O | Ca₂Al₃(SiO₄)₃(OH) | ZrSiO₄ |
| Mohs Hardness | 5 – 6 | 6.5 – 7 | 6.5 – 7.5 |
| Crystal System | Triclinic | Orthorhombic | Tetragonal |
| Refractive Index | 1.610 – 1.650 | 1.691 – 1.700 | 1.92 – 1.98 |
| Specific Gravity | 2.60 – 2.90 | 3.35 | 4.6 – 4.7 |
| Optical Character | Opaque to semi-translucent | Transparent | Transparent to translucent |
| Key Inclusions | Matrix (host rock remnants), spiderweb patterns. | Zoisite needles, inclusions are common. | Zircon crystals, liquid inclusions, "zircon twins." |
| Color Range | Sky blue, greenish-blue, with matrix. | Vivid violet-blue, blue-violet. | Icy pale blue to deep blue. |
| Durability | Low to moderate; porous, prone to cracking, sensitive to chemicals, heat, and light. | Moderate; good hardness but can be brittle due to cleavage. | High hardness but has poor toughness due to cleavage; susceptible to chipping. |
| Treatments | Stabilization (impregnation with resin) is common to improve durability and color. | Heat treatment is standard to enhance blue color. | Heat treatment is standard to enhance color (from brown to blue). |
Turquoise is the softest and most delicate of the three. Its hardness of 5–6 on the Mohs scale makes it susceptible to scratching and abrasion. Its porosity means it can absorb oils, chemicals, and cosmetics, which can dull its color and luster. Most commercial Turquoise is "stabilized," meaning it is impregnated with a clear resin under pressure to increase its durability and lock in the color. This is a standard and accepted industry practice.
Tanzanite has a good hardness (6.5–7) but is known for its "perfect cleavage" in one direction, meaning it can split along a plane if struck with force. This makes it more susceptible to chipping than a gem like Sapphire, which lacks cleavage. Care must be taken when setting and wearing Tanzanite jewelry.
Zircon is one of the hardest natural gemstones (6.5–7.5), close to that of Sapphire and Ruby. However, it also has perfect cleavage, making it brittle and prone to chipping or cracking if impacted. Its high refractive index (1.92–1.98) gives it exceptional brilliance and fire, often rivaling that of diamond. It is one of the few gemstones that can exhibit double refraction, which can be observed with a loupe.
Symbolism and Metaphysical Beliefs
Across cultures and centuries, these December birthstones have been imbued with profound symbolic meaning.
Turquoise is universally regarded as a stone of protection, wisdom, and good fortune. Its color is often associated with the sky and water, elements of life and tranquility. In many cultures, it is believed to connect the wearer to the spiritual world and to promote inner calm and balance. It is also known as a stone of friendship, said to foster trust and understanding between people. For those born under Sagittarius (Nov 22 – Dec 21), Turquoise is said to support their honest, dynamic energy and quest for truth. For Capricorn (Dec 22 – Jan 19), it offers emotional balance and protection.
Tanzanite, a gem of the modern era, is associated with transformation, intuition, and emotional healing. Its striking violet-blue color is often linked to the higher chakras and spiritual awareness. It is believed to facilitate communication with one's higher self and to provide a sense of clarity and purpose. For Capricorns, Tanzanite is said to aid in focus and ambition while supporting emotional healing, making it an ideal stone for those born on dates like December 27.
Zircon has long been associated with wisdom, honor, and purity. Its brilliant sparkle is thought to inspire clarity of thought and to enhance self-confidence. Historically, it was believed to bring prosperity and to protect the wearer from negative energies. Its durability and enduring beauty make it a symbol of stability and long-lasting success.
Blue Topaz, as a modern alternative, embodies calmness, clarity, and communication. Its cool blue hues are associated with soothing energies, reducing stress and anxiety. It is often linked to the throat chakra, making it a stone for clear and honest communication.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of any gemstone, and the December birthstones each have specific requirements due to their unique physical properties.
Turquoise Care: Due to its porosity and relative softness, Turquoise requires gentle handling. * Cleaning: Use only a soft, dry cloth. Avoid water, chemicals, and ultrasonic cleaners, as they can damage the stone or its stabilizing treatment. For a deeper clean, use a damp cloth with mild soap, but dry immediately. * Storage: Store separately in a soft pouch to avoid scratches from harder gems. * Wearing: Apply cosmetics, perfumes, and hairsprays before putting on Turquoise jewelry to prevent chemical exposure.
Tanzanite Care: While harder than Turquoise, its cleavage makes it vulnerable to impact. * Cleaning: Use warm, soapy water and a soft brush. Avoid ultrasonic and steam cleaners, as the vibrations and heat can cause the stone to crack along its cleavage planes. * Storage: Store in a fabric-lined jewelry box, ideally in its own compartment to prevent contact with other gems that could scratch or chip it. * Wearing: It is best to remove Tanzanite jewelry during physical activities, gardening, or household chores.
Zircon Care: Zircon's hardness is an advantage, but its brittleness is a concern. * Cleaning: Safe to clean with warm, soapy water and a soft brush. Ultrasonic cleaners are generally not recommended due to the risk of chipping from the vibrations. Steam cleaning should also be avoided. * Storage: Store carefully, ideally in a padded box. Given its hardness, it can scratch other gems, so separate storage is advised. * Wearing: Due to its brittleness, Zircon jewelry should be worn with care, avoiding hard impacts.
Blue Topaz Care: Blue Topaz is relatively durable but can be sensitive to heat and light in its natural state. * Cleaning: It is safe to use warm, soapy water and a soft brush. Ultrasonic cleaners are generally safe, but steam cleaning is not recommended. * Storage: Store away from direct sunlight for prolonged periods, as some colored Topaz can fade over time when exposed to strong light and heat. * Wearing: It is a good choice for everyday wear but should still be protected from hard blows.
Conclusion
The December birthstones—Turquoise, Tanzanite, and Zircon—offer a captivating range of options that reflect the month's serene and festive spirit. From the ancient, protective lore of Turquoise to the modern, transformative symbolism of Tanzanite and the brilliant, wise sparkle of Zircon, each gem carries a unique story. Their geological origins, from the arid deserts of Iran to the single, remote location in Tanzania, add to their mystique and value. While they differ in hardness, color, and care requirements, they are united by their stunning blue hues and their enduring appeal. For those born in December, this trio of gems provides not just a beautiful accessory but a meaningful connection to history, science, and personal identity. Whether chosen for its traditional significance, its vibrant color, or its modern allure, a December birthstone is a timeless treasure.