For those born on December 24th, the world of gemstones offers a unique and captivating selection. The primary birthstones for this date are Tanzanite, Turquoise, and Zircon, each celebrated for its distinct blue hues that evoke the cool serenity of winter. While these three stones share a common color family, they possess vastly different origins, properties, and histories. This article delves into the geological formation, gemological properties, historical lore, and cultural significance of these three remarkable gems, providing a detailed guide for gemstone enthusiasts, collectors, and individuals seeking a meaningful connection to their birthstone.
The choice of December 24th birthstones is not arbitrary. It reflects a tradition that has evolved over time, with modern additions offering a broader palette of blue tones. While some sources list additional stones like Blue Topaz or Bloodstone as alternatives, the core trio of Tanzanite, Turquoise, and Zircon is consistently recognized across authoritative gemological and historical references. Understanding each stone’s unique characteristics—from the rare, single-origin discovery of Tanzanite to the ancient, protective lore of Turquoise and the brilliant, fiery sparkle of Zircon—allows for a deeper appreciation of these gems beyond their aesthetic appeal.
History and Lore
The journey of these stones to becoming December’s birthstones is a story of ancient tradition, modern discovery, and cultural evolution. The concept of birthstones is rooted in biblical history, specifically the twelve gemstones adorning the breastplate of Aaron, as described in the Book of Exodus. This ancient list, which served as a foundation for later traditions, assigned a gemstone to each of the twelve tribes of Israel. Over centuries, this practice evolved, with different cultures assigning stones to months based on their own interpretations and available gems.
The modern standardized birthstone list, however, is a more recent development. In 1912, the National Association of Jewelers in the United States formalized an unofficial list, aiming to combine traditional customs with gemstones that were practical for the jewelry trade. This list has been updated several times since. For December, the evolution is particularly notable. Initially, Turquoise was the primary stone. In 1952, the Jewelry Industry Council of America added Zircon to the list, and in 2002, Tanzanite was officially recognized as a modern birthstone for December. This progressive inclusion reflects both the discovery of new gemstones and the desire to offer consumers a wider variety of choices.
Turquoise holds the title of the traditional and oldest birthstone for December. Its history spans thousands of years, with archaeological evidence of its use in ancient Egypt, Mesopotamia, and the Americas. In many cultures, Turquoise is considered a sacred stone. It has been revered for its perceived ability to provide protection, promote good fortune, and symbolize friendship. Its name is derived from the French pierre turquoise, meaning "Turkish stone," as it was originally brought to Europe from Persia through Turkish traders. In Native American cultures, particularly among the Navajo, Zuni, and Hopi peoples, Turquoise is not merely decorative but is deeply embedded in spiritual practices and is believed to connect the wearer to the sky and water.
Zircon, while often confused with the synthetic cubic zirconia, is one of the oldest minerals on Earth. The blue variety of Zircon, which is the most popular for birthstones, has a rich history of its own. Historically, Zircon was believed to possess powerful properties. It was thought to lull people to sleep and ward off evil spirits and nightmares. Furthermore, Zircon is one of the nine gemstones known as Navaratna in Indian astrology and culture. These nine gems are said to bring wisdom, wealth, and protection from evil to the wearer, with Zircon specifically associated with Venus. Its use in jewelry dates back centuries, and its fiery brilliance has made it a prized gem for royalty and nobility throughout history.
Tanzanite is the newest addition to the December birthstone family, with a history that is entirely modern. It was first discovered in 1967 in the Merelani Hills of Tanzania, East Africa, near the foot of Mount Kilimanjaro. This discovery was made by a local Masai tribesman, and the stone was later identified by the New York-based gemologist John Hardy. Initially, it was believed to be a new variety of the mineral zoisite, but its unique blue-purple color, a result of vanadium trace elements and subsequent heat treatment, set it apart. The gem was named after its country of origin. Its rapid rise to prominence is a testament to its captivating beauty. The late actress Elizabeth Taylor’s love for the stone in the 1970s, coupled with its exclusive geographic origin, fueled its popularity and cemented its status as a luxury gem. Its association with transformation and new beginnings is a modern interpretation, aligning with its recent discovery and the dramatic change it undergoes when heated.
Geological Formation and Sources
The origins of these three birthstones could not be more different, spanning from ancient geological processes to a singular, recent discovery.
Turquoise is a hydrous phosphate of copper and aluminum, formed in arid regions where acidic, copper-rich water seeps through pre-existing rock, replacing minerals and creating nodules or veins. Its formation requires a precise combination of specific geological conditions, which is why its deposits are limited to a few regions worldwide. The most historically significant sources include the Nishapur region of Iran (Persia), which produces the highly prized "robin's egg blue" turquoise. In the United States, the Southwest is a major producer, with states like Arizona and New Mexico yielding significant quantities. Other sources include Tibet, China, and Egypt. The color of turquoise is directly influenced by the presence of copper (blue) and iron (greenish hues), and its matrix (the host rock) can create unique patterns, such as the spiderweb matrix found in some Persian and Egyptian stones.
Zircon is a zirconium silicate (ZrSiO₄) and is one of the oldest minerals on Earth, with some crystals dating back billions of years. It forms in pegmatites, metamorphic rocks, and in igneous rocks like granite and syenite. While Zircon occurs in many colors, the blue variety used in jewelry is typically created by heating brown or yellow zircon crystals to high temperatures, which alters their crystal structure and removes the color-causing impurities. The primary sources for gem-quality zircon include Australia, which produces a significant amount of the world’s supply, particularly from the New England region of New South Wales. Other important sources are Sri Lanka, Cambodia, Myanmar (Burma), and Brazil. The stone’s durability and brilliance make it a popular choice for both jewelry and industrial applications, such as in the manufacture of ceramic tiles and refractory products.
Tanzanite is the rarest of the three, with its entire known commercial supply coming from a single, small mining area in the Merelani Hills of Tanzania. This geological uniqueness is a direct result of a specific set of conditions that occurred during the formation of the East African Rift system. The stone is a variety of the mineral zoisite, colored by vanadium and heated naturally by the region's geothermal activity. The mining area is divided into four blocks, with Block D being the most productive. Due to its extreme rarity and limited geographic source, the supply of tanzanite is finite, which contributes to its high value and status. Unlike diamonds or sapphires, which are found in multiple locations worldwide, all tanzanite in existence originates from this one small area, making it a true geological oddity.
Gemological Properties
Understanding the physical and optical properties of these gems is essential for appreciating their unique characteristics and for making informed decisions about care and wear.
| Property | Tanzanite | Turquoise | Zircon (Blue) |
|---|---|---|---|
| Chemical Formula | Ca₂Al₃(SiO₄)₃(OH) | CuAl₆(PO₄)₄(OH)₈·4H₂O | ZrSiO₄ |
| Crystal System | Orthorhombic | Triclinic | Tetragonal |
| Hardness (Mohs) | 6.5 - 7 | 5 - 6 | 6.5 - 7.5 |
| Refractive Index | 1.691 - 1.700 | 1.610 - 1.650 | 1.925 - 2.015 |
| Specific Gravity | 3.35 - 3.38 | 2.60 - 2.90 | 4.60 - 4.70 |
| Luster | Vitreous to silky | Waxy to dull | Adamantine |
| Transparency | Translucent to opaque | Opaque | Transparent to translucent |
| Pleochroism | Strong (trichroic) | None | Weak to strong |
Tanzanite is prized for its remarkable pleochroism, a property where the stone displays different colors when viewed from different crystallographic directions. A well-cut tanzanite can show a trichroic display of blue, violet, and a reddish hue. Its hardness of 6.5 to 7 on the Mohs scale makes it moderately durable, but it is still susceptible to scratching and chipping, requiring careful handling. It is typically cut into faceted shapes to maximize its color and brilliance. The most valuable tanzanites exhibit a deep, saturated violet-blue color, often described as "vivid" or "intense."
Turquoise is an opaque gemstone, meaning light does not pass through it. Its color ranges from sky blue to greenish-blue, depending on the amount of copper and iron present. It has a hardness of 5 to 6, making it relatively soft and porous. This porosity means it can absorb oils and chemicals, which can alter its color over time. Turquoise is often treated to enhance its color and durability. Common treatments include dyeing (to produce a more uniform blue) and stabilization (impregnating the stone with a clear resin or wax to reduce porosity). The quality of turquoise is often judged by its color, uniformity, and the presence and pattern of its matrix (the host rock inclusions).
Zircon is renowned for its exceptional adamantine luster, which gives it a brilliant, diamond-like sparkle. Blue zircon is typically created by heat-treating brown zircon crystals, a process that is permanent and widely accepted in the gem trade. Its hardness ranges from 6.5 to 7.5, making it more durable than both tanzanite and turquoise, though still softer than sapphire or diamond. Zircon has a high refractive index and strong dispersion, which contributes to its fiery brilliance. It is important to distinguish natural zircon from synthetic cubic zirconia (CZ), which is a completely different material. Natural zircon is a valuable gemstone in its own right, with a history that predates many other gems.
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, these birthstones are imbued with a rich tapestry of symbolic meanings and metaphysical beliefs, which have been passed down through generations.
Turquoise is universally regarded as a stone of protection, healing, and good fortune. In many cultures, it is believed to be a powerful shield against negative energy and harm. For warriors, it was a talisman of safety and victory. For travelers, it was a guide to safety. Its connection to the sky and water in Native American traditions symbolizes spiritual grounding and a connection to the natural world. It is also associated with friendship, love, and emotional balance, said to promote calm and tranquility. The stone is thought to attune the wearer to their own intuition and to help overcome self-sabotage.
Zircon carries meanings of wisdom, honor, and purity. In Hindu astrology, as part of the Navaratna, it is believed to bring prosperity and protect the wearer from evil. Historically, it was thought to promote honor and purity in the wearer. Its brilliant sparkle is associated with clarity of thought and spiritual enlightenment. Some beliefs suggest that zircon can help with insomnia and induce peaceful sleep, a nod to its ancient reputation as a sleep aid. It is also seen as a stone of grounding and stability, helping to balance emotional and physical energies.
Tanzanite, as a modern discovery, has been assigned contemporary metaphysical properties that align with its dramatic appearance and origin. It is often called the "stone of transformation" and is believed to facilitate major life changes, spiritual awakening, and new beginnings. Its striking blue color is associated with the higher chakras, particularly the throat and third eye chakras, enhancing communication, intuition, and psychic abilities. It is thought to promote a sense of calm and tranquility, helping to alleviate stress and anxiety. Its rarity is also symbolic, encouraging the wearer to embrace their unique path and potential.
Care and Cleaning
Proper care is crucial to maintaining the beauty and longevity of these gemstones, especially given their varying degrees of hardness and porosity.
Turquoise, with its softness (5-6 Mohs) and porosity, is the most delicate of the three. It should be protected from harsh chemicals, including perfumes, lotions, and cleaning agents, which can damage its surface and alter its color. Cleaning should be done with a soft, dry cloth. Avoid soaking turquoise in water or using ultrasonic cleaners, as this can cause cracking or discoloration. It is best to put on turquoise jewelry after applying cosmetics and to remove it before swimming or bathing.
Tanzanite (6.5-7 Mohs) is more durable than turquoise but still requires careful handling. It is prone to scratching and chipping, so it should be stored separately from other jewelry to avoid contact with harder gems. While it can be cleaned with warm, soapy water and a soft brush, it should not be exposed to sudden temperature changes, which can cause internal stress. Ultrasonic cleaners and steam cleaners are not recommended, as they can cause fractures in the stone.
Zircon (6.5-7.5 Mohs) is the most durable of the December 24th birthstones, but it still has some vulnerabilities. It can be brittle and prone to chipping due to its crystal structure. It is also sensitive to heat and sudden temperature changes, which can cause it to fracture. Therefore, it is not recommended to use an ultrasonic cleaner or expose zircon to high heat. The safest cleaning method is warm, soapy water with a soft brush. Due to its high refractive index, zircon can show inclusions more readily than some other gems, so it is important to handle it with care to avoid damage.
Conclusion
The birthstones for December 24th—Tanzanite, Turquoise, and Zircon—offer a remarkable study in diversity. From the ancient, protective lore of Turquoise to the fiery, diamond-like brilliance of Zircon and the modern, transformative allure of Tanzanite, each gem tells a unique story. Their origins span the globe, from the arid landscapes of the American Southwest and the ancient crust of Australia to a single, geologically unique mine in Tanzania. Their properties, from the soft, opaque beauty of turquoise to the vibrant, pleochroic display of tanzanite and the sparkling clarity of zircon, cater to a wide range of tastes and styles.
For the individual born on December 24th, the choice of a birthstone is deeply personal. It may be guided by the stone's historical significance, its metaphysical properties, its aesthetic appeal, or its durability. Whether one is drawn to the serene, sky-blue hues of turquoise, the deep, shifting blues of tanzanite, or the brilliant, clear sparkle of zircon, each gem provides a meaningful connection to one's birth date. These stones are not merely decorative; they are carriers of history, culture, and belief, making them a timeless and significant choice for jewelry and personal adornment.