December is a month of profound contrasts, marked by the deepening winter chill and the festive spirit of renewal. For those born in this final month of the year, the birthstones are a reflection of this duality: cool, crystalline blues that evoke icy landscapes and serene skies. Unlike any other month, December boasts four officially recognized birthstones: Turquoise, Tanzanite, Zircon, and Blue Topaz. Each gemstone possesses a unique geological origin, a distinct history, and a specific set of properties that cater to a wide range of tastes and budgets. This article provides a detailed exploration of these four blue treasures, delving into their histories, gemological characteristics, symbolic meanings, and practical considerations for care and ownership.
The expansion of December's birthstone list is a relatively modern phenomenon, driven by commercial and practical considerations within the jewelry industry. In 1912, the National Association of Jewelers in the United States standardized a list of birthstones, a list that has been updated several times since. The addition of new stones, particularly to December, was often intended to provide more affordable and accessible options for consumers. This evolution underscores the dynamic nature of birthstone traditions, which blend ancient customs with contemporary market demands. The result is a diverse portfolio of blue gems, allowing individuals to select a stone that resonates with their personal style, from the earthy, ancient allure of turquoise to the vivid, modern brilliance of tanzanite.
History and Lore: From Ancient Talismans to Modern Standards
The concept of birthstones is deeply rooted in antiquity, with origins tracing back to the breastplate of Aaron described in the Book of Exodus, which featured twelve gemstones representing the twelve tribes of Israel. Over centuries, this biblical connection evolved into the belief that wearing a specific gemstone corresponding to one's birth month could bring luck, health, and protection. The modern standardized list, however, is a product of the 20th century.
The journey of December's birthstones to their current status is a story of gradual inclusion. Turquoise, with its rich history spanning millennia, is the most ancient of the four. It has been cherished by civilizations from ancient Egypt and Persia to the Native American tribes of the southwestern United States, where it remains a sacred and culturally significant stone. Its initial inclusion in birthstone lists was a natural extension of its long-standing esteem.
The other three stones were added later to modernize and expand the list. In 1952, the Jewelry Industry Council of America updated the official list, adding Zircon to December's offerings. Zircon, one of the oldest minerals on Earth, has been used for centuries, but its designation as a December birthstone is a more recent commercial and cultural decision. The most recent addition is Tanzanite, which was officially added to the birthstone list in 2002. This inclusion reflects the gemstone's rapid rise in popularity following its discovery in 1967 and its subsequent marketing as a rare and precious gem. Blue Topaz, while not added at a specific date like the others, has become a modern staple for December, widely recognized in the United States as a contemporary birthstone option, prized for its affordability and vibrant color.
The reason for December having four birthstones is not definitively known, but sources suggest it may have been to provide a range of affordable options. The evolution of birthstone lists continues to be influenced by new gemstone discoveries and commercial offerings, making December a uniquely versatile month for birthstone selection.
Geological Formation and Global Sources
Each of December's birthstones has a distinct geological origin, contributing to its unique appearance and properties.
Turquoise is an opaque, blue-to-green mineral that is a hydrated phosphate of copper and aluminum. It forms in arid regions where acidic, copper-rich groundwater seeps through rocks containing aluminum and phosphorus. Over millennia, the deposition of these minerals creates veins and nodules of turquoise. The most significant sources are in the United States (particularly Arizona and New Mexico), Iran, and Egypt. The color is directly tied to its copper content, with higher copper levels producing a more intense blue.
Tanzanite is a relative newcomer to the gemological world, a variety of the mineral zoisite. It was first discovered in 1967 in the Merelani Hills of Tanzania, making it one of the few major gemstones found in a single, geologically restricted location. This extreme rarity is a key factor in its value and allure. Tanzanite is formed by the intense heat and pressure from tectonic plate activity in the East African Rift Valley, which transforms the original zoisite into its vibrant blue-violet form. Its limited geographic source makes it exceptionally rare, with some geologists estimating that the known deposits may be exhausted within a few decades.
Zircon is a mineral composed of zirconium silicate. It is one of the oldest minerals on Earth, with crystals dating back billions of years. While zircon occurs in a variety of colors, the blue variety used as a birthstone is typically heat-treated to achieve its desirable hue. Natural blue zircon is rare. Major sources include Cambodia, Myanmar, and Sri Lanka. The gemstone's high refractive index gives it exceptional brilliance and fire, often compared to that of diamond.
Blue Topaz is a silicate mineral composed of aluminum and fluorine. While topaz occurs naturally in a range of colors, natural blue topaz is quite rare. The vast majority of blue topaz in the market is created by irradiating colorless topaz, which is abundant. This treatment process makes blue topaz widely available and affordable. Major sources of the base material include Sri Lanka, Brazil, Mexico, Nigeria, and the United States (Texas, where it is the official state gem). The specific shade of blue—ranging from Sky Blue to the deeper London Blue—is controlled by the intensity of the irradiation process.
Gemological Properties: A Scientific Comparison
Understanding the physical and chemical properties of these gems is essential for selection, care, and valuation. The following table summarizes key gemological characteristics based on the provided sources.
| Gemstone | Chemical Composition | Hardness (Mohs Scale) | Typical Color(s) | Key Distinguishing Features |
|---|---|---|---|---|
| Turquoise | Hydrated phosphate of copper & aluminum (CuAl₆(PO₄)₄(OH)₈·4H₂O) | 5 - 6 | Sky blue to greenish-blue, often with matrix | Opaque; color from copper; can be porous. |
| Tanzanite | Calcium aluminum hydroxyl sorosilicate (Ca₂Al₃(SiO₄)₃(OH)) | 6.5 - 7 | Vivid blue-violet, pleochroic (blue, violet, burgundy) | Trichroic; only mined in Tanzania; sensitive to heat. |
| Zircon | Zirconium silicate (ZrSiO₄) | 6.5 - 7.5 | Blue, often heat-treated | High refractive index (brilliance); can be brittle. |
| Blue Topaz | Aluminum fluorosilicate (Al₂SiO₄(F,OH)₂) | 8 | Pale blue to deep inky blue (London Blue) | Hardest of the December stones; deep cleavage; most are irradiated. |
Hardness and Durability: Hardness, measured on the Mohs scale, indicates a gemstone's resistance to scratching. Blue Topaz is the most durable of the four December birthstones, with a hardness of 8, making it an excellent choice for everyday jewelry like rings. Zircon and Tanzanite follow closely with a hardness range of 6.5 to 7.5, but zircon can be brittle and prone to chipping due to its cleavage. Turquoise, with a hardness of 5 to 6, is the softest and most porous of the group, requiring more careful handling and protection from chemicals and abrasion.
Color and Treatment: The blue hues of these stones originate from different causes. Turquoise's color is a natural result of copper content. Tanzanite's color is also natural, though heat treatment is commonly used to enhance the blue hue and remove brownish tones. Zircon's blue color is often achieved through heat treatment of brown or colorless crystals. Blue topaz is almost exclusively the product of irradiation of colorless topaz, a process that is stable and permanent. The resulting shades include Sky Blue (light aqua), Swiss Blue (vibrant medium blue), and London Blue (deep, inky blue).
Clarity and Luster: Turquoise is typically opaque, often containing a matrix of host rock. Tanzanite, Zircon, and Blue Topaz are transparent to translucent. Zircon has a brilliant, diamond-like luster due to its high refractive index. Blue topaz has a glass-like luster, and tanzanite exhibits a vitreous to adamantine luster. Inclusions are common in turquoise and can be part of its character, while tanzanite and zircon are valued for their clarity, though inclusions can affect durability.
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, December's birthstones are steeped in symbolism and metaphysical lore, beliefs that have been passed down through generations.
Turquoise is perhaps the most spiritually significant of the four. For centuries, it has been regarded as a sacred stone, a conduit for communication with the spiritual world and a powerful protector. It is often called the "Master Healer" and is believed to align all chakras, stabilize mood, and promote inner calm. In many cultures, turquoise is seen as a stone of friendship, wisdom, and tranquility.
Tanzanite, as a modern discovery, carries more contemporary symbolic meanings. It is often associated with transformation, intuition, and spiritual awakening. Its striking trichroic nature—showing blue, violet, and burgundy tones—is seen as a metaphor for seeing a situation from multiple perspectives. It is believed to facilitate higher consciousness and open the mind to new possibilities.
Zircon, one of the oldest minerals, is linked to ancient wisdom and purity. It is said to promote honor, purity, and spiritual growth. Blue zircon, in particular, is associated with peace and tranquility, helping to calm an overactive mind and encouraging a restful sleep. Its brilliant fire is thought to inspire clarity of thought and purpose.
Blue Topaz is widely associated with calm, peace, and communication. It is believed to soothe the mind, alleviate stress and anxiety, and promote honest self-expression. It is often called the "Stone of Truth," helping individuals to articulate their thoughts and feelings with clarity and confidence. It is also linked to loyalty and love, making it a meaningful gift for loved ones.
Care and Cleaning: Preserving Your Gemstone
Proper care is essential to maintain the beauty and longevity of any gemstone. The required level of care varies significantly among December's birthstones due to differences in hardness and stability.
Turquoise: Due to its porosity and softness, turquoise requires the most care. It should be protected from chemicals, perfumes, lotions, and prolonged exposure to water, which can cause discoloration or cracking. Clean turquoise jewelry with a soft, dry cloth. Avoid ultrasonic and steam cleaners. Store it separately to prevent scratching.
Tanzanite: With a hardness of 6.5-7, tanzanite is moderately durable but has perfect cleavage in one direction, making it susceptible to chipping or cracking if struck hard. It is also sensitive to sudden temperature changes. It is best to clean tanzanite with warm, soapy water and a soft brush. Avoid ultrasonic cleaners and harsh chemicals. Remove tanzanite jewelry during physical activities.
Zircon: While zircon has good hardness, it can be brittle and prone to cleaving. It is also sensitive to heat, which can alter its color. Avoid ultrasonic cleaners and steam cleaning, as the vibrations and heat can cause damage. The safest cleaning method is warm, soapy water with a soft brush. Store zircon pieces carefully to avoid contact with harder gems.
Blue Topaz: As the hardest of the group, blue topaz is the most durable for everyday wear. However, it has perfect cleavage in one direction, meaning it can split if struck with sufficient force along that plane. It is generally stable under normal conditions. Clean blue topaz with warm, soapy water and a soft brush. While it can often withstand an ultrasonic cleaner, it is safer to avoid them if the stone is set in a delicate or old piece of jewelry.
Conclusion
The four birthstones of December—Turquoise, Tanzanite, Zircon, and Blue Topaz—offer a remarkable spectrum of blue gemstones, each with a unique story. From the ancient, protective talisman of turquoise to the rare, transformative beauty of tanzanite, the brilliant fire of zircon, and the accessible, serene calm of blue topaz, these gems provide a perfect match for every personality and preference. Their collective history reflects the evolution of gemology and commerce, while their individual properties highlight the incredible diversity of the mineral kingdom. For those born in December, this abundance of choice is a gift, allowing them to wear not just a beautiful piece of jewelry, but a stone imbued with personal significance, historical depth, and enduring beauty.