The month of December is uniquely associated with a quartet of gemstones, a distinction shared with no other month in the modern birthstone calendar. This abundance offers a remarkable spectrum of blue hues, each stone embodying a distinct history, geological origin, and cultural significance. The traditional birthstones for December are Turquoise, Zircon, and Tanzanite, with Blue Topaz widely recognized as a modern addition, particularly in the United States. These gemstones collectively mirror the wintry landscapes of the season—from the tranquil, earthy tones of turquoise to the brilliant, icy sparkle of zircon and the deep, shifting blues of tanzanite and topaz. This article explores the multifaceted world of December’s birthstones, delving into their historical journeys, geological formations, gemological properties, and enduring symbolism, providing a comprehensive guide for gemstone enthusiasts, jewelry buyers, and students of gemology.
History and Lore
The concept of birthstones is ancient, with roots tracing back to civilizations such as ancient Egypt, Greece, and Rome, where gemstones were believed to possess mystical and healing properties. Over time, these beliefs evolved into the standardized birthstone lists we recognize today.
Turquoise stands as the most historically significant of December’s stones. It has been cherished by royalty for millennia, most famously by King Tutankhamun of ancient Egypt, who was buried with an array of turquoise artifacts. For centuries, this mineral was thought to provide protection from harm, including falls and negative energy. Its use as a protective talisman persisted across cultures, from the ancient Persians to the Native American tribes of the Southwest. Today, its symbolism has softened to represent wisdom, tranquility, and friendship.
Blue Zircon and Tanzanite have more recent journeys into the birthstone canon. Zircon, one of the oldest minerals on Earth, has been used in jewelry for centuries, but its specific association with December is a modern development. In 1952, the Jewelry Industry Council of America updated the official birthstone list, adding blue zircon to December’s offerings. This decision likely aimed to provide more variety and affordability. Tanzanite is the newest member of the group, with its discovery in the 20th century. It was added to the official birthstone list in 2002 by the American Gem Trade Association (AGTA), reflecting the tradition of updating lists to include newly discovered and popular gemstones. Its rapid inclusion speaks to its captivating beauty and rarity.
Blue Topaz, while not a traditional birthstone for December, has become a prominent modern alternative, especially in the United States. Its exact historical origin is unclear, as blue topaz has been found throughout history, though often confused with other blue stones. Its journey to becoming a December birthstone is tied to commercial and practical considerations. In 1912, the National Association of Jewelers standardized the unofficial American birthstone list, combining customs with gemstones that would be practical for jewelry companies to sell. Blue Topaz, with its desirable color and durability, naturally found its place as an affordable and beautiful option for December-born individuals.
The reason December has four birthstones is not definitively known, but it is widely believed to be a result of both historical evolution and commercial strategy. As new gemstones were discovered or gained popularity, they were added to the list to offer more choices and cater to different preferences and budgets. This evolution ensures that December’s birthstones remain relevant and accessible.
Geological Formation and Sources
Each of December’s birthstones forms under distinct geological conditions, leading to their unique appearances and sources.
Turquoise is a secondary mineral formed in arid regions where water carrying dissolved copper and aluminum percolates through pre-existing rocks. This process occurs in areas with copper-rich geological formations and specific weather conditions that facilitate its formation. Consequently, turquoise is primarily mined in arid regions of the world. Significant sources include the southwestern United States (particularly Arizona and New Mexico), Iran, Egypt, China, Mexico, and parts of Central Asia and Africa. It often exhibits a matrix-like appearance, where host rock fragments are incorporated into the gem, creating distinctive spiderweb patterns.
Blue Zircon is a mineral belonging to the nesosilicate group, formed from the alteration of other minerals during high-temperature geological events. While zircon crystals are found worldwide, gem-quality blue zircon is relatively rare. Historically, it has been sourced from Cambodia and Sri Lanka. The bright, clear blue color prized in jewelry is often the result of heat treatment applied to brown zircon crystals, a common practice that enhances its appeal.
Tanzanite is an exceptionally rare gemstone, found in only one location on Earth: the Merelani Hills of northern Tanzania, near the foothills of Mount Kilimanjaro. This geographic limitation makes it one of the rarest gemstones in the world. It forms under unique geological conditions involving the metamorphism of the host rock. Its scarcity is a primary factor in its high value and cost.
Blue Topaz is mined in several countries around the world, including Sri Lanka, Brazil, Mexico, Nigeria, and the United States. It is the official state gem of Texas. Topaz is a silicate mineral that forms in igneous rocks, particularly in pegmatites and high-temperature veins. The vivid blue color of most commercial blue topaz is achieved through irradiation and heat treatment of colorless or pale topaz, a standard industry practice that produces stable and attractive hues.
Gemological Properties
Understanding the physical and chemical properties of these gemstones is crucial for appreciating their value, durability, and care requirements.
Turquoise is a hydrated phosphate of copper and aluminum. Its hardness on the Mohs scale is relatively low, typically around 5 to 6, making it a relatively soft and porous gemstone. This softness means it can be scratched easily and is susceptible to damage from chemicals, perfumes, and even skin oils, which can alter its color over time. It often contains a matrix (host rock) and may be stabilized with resins to improve durability.
Blue Zircon is a much harder gemstone, with a Mohs hardness of 7 to 7.5. This makes it suitable for various types of jewelry, though care should still be taken to avoid sharp blows. It has a high refractive index, giving it a brilliant sparkle that can rival diamond. It is pleochroic, meaning it can show different shades of blue when viewed from different angles.
Tanzanite is a variety of the mineral zoisite and is relatively soft, with a Mohs hardness of 6 to 7. It is also strongly pleochroic, displaying a dramatic color shift from blue to violet to burgundy depending on the crystal orientation and lighting conditions. This characteristic is a key identifying feature. Its softness and perfect cleavage in one direction make it susceptible to chipping and breaking, requiring protective settings for jewelry.
Blue Topaz is the hardest of the December birthstones, with a Mohs hardness of 8. This makes it exceptionally durable and resistant to scratching, ideal for everyday wear in rings and bracelets. It is a silicate mineral with a chemical formula of Al₂SiO₄(F,OH)₂. Its hardness, combined with its affordability and vibrant color, contributes to its popularity.
Comparative Gemological Properties
The following table summarizes key properties of the four December birthstones based on the provided sources.
| Gemstone | Mineral Family | Mohs Hardness | Key Identifying Feature | Primary Color |
|---|---|---|---|---|
| Turquoise | Phosphate | 5 - 6 | Matrix patterns, porous nature | Light blue to greenish-blue |
| Blue Zircon | Nesosilicate | 7 - 7.5 | High brilliance, pleochroism | Bright, clear blue |
| Tanzanite | Zoisite | 6 - 7 | Strong pleochroism (color shift) | Violet-blue to burgundy |
| Blue Topaz | Silicate | 8 | Exceptional hardness, clarity | Pale to vivid sky blue |
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, December’s birthstones are steeped in symbolism and metaphysical beliefs that have evolved over centuries.
Turquoise has long been associated with protection and good fortune. Ancient cultures believed it could ward off evil spirits and prevent falls, making it a popular amulet for warriors and travelers. In modern metaphysical beliefs, it is seen as a stone of wisdom, tranquility, and friendship. It is thought to promote emotional balance and calm, serving as a steadying force during chaotic times.
Tanzanite, being a modern discovery, has accumulated symbolic meanings more recently. It is linked to transformation, growth, and new beginnings. Its vivid blue-violet hue is said to encourage clarity, curiosity, and a fresh perspective, making it a stone for those stepping into new chapters of life. It is also believed to facilitate spiritual awakening and higher consciousness.
Zircon (specifically blue zircon) is associated with sharpening focus and boosting mental clarity. It is thought to promote wisdom, honor, and purity. Some beliefs hold that it can help with spiritual grounding and provide a sense of balance and stability.
Blue Topaz is often connected to communication and emotional expression. It is believed to aid in clear thinking and honest communication, making it a stone for public speakers and artists. Its calming blue color is also associated with peace, serenity, and relaxation, helping to soothe anxiety and stress.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of these gemstones, and their care requirements vary significantly based on their physical properties.
Turquoise requires the most delicate handling due to its softness and porosity. It should be cleaned only with a soft, dry cloth. Avoid exposing it to water, chemicals, perfumes, lotions, or extreme temperatures, as these can cause discoloration, cracking, or damage to any stabilizing resins. Store turquoise jewelry separately to prevent scratching.
Blue Zircon, with its higher hardness, can be cleaned with warm water, mild soap, and a soft brush. It is important to avoid ultrasonic cleaners and steam, as sudden temperature changes can cause fractures in some zircon crystals. It should also be stored carefully to prevent scratching from harder gems.
Tanzanite is relatively fragile and requires careful handling. It can be cleaned with warm, soapy water and a soft brush, but it should never be placed in an ultrasonic cleaner or exposed to steam, as this can cause it to fracture. Due to its perfect cleavage, it is best set in protective jewelry settings like bezels for rings to avoid impact damage.
Blue Topaz is the most durable of the group and can be cleaned safely with warm, soapy water and a soft brush. It is generally safe for ultrasonic cleaning, but it is always best to check with a professional jeweler first, especially if the stone is set. Its hardness makes it resistant to scratching, but it can still be chipped by a sharp blow.
Conclusion
December’s quartet of birthstones—Turquoise, Zircon, Tanzanite, and Blue Topaz—offers a remarkable diversity that reflects the complexity and beauty of the winter season. From the ancient, protective talisman of turquoise to the rare, modern allure of tanzanite, each gemstone carries a unique story. Their geological origins span the globe, from the arid regions of the American Southwest to the single, remote valley in Tanzania. Their gemological properties range from the soft and porous to the exceptionally hard and brilliant, dictating their care and suitability for jewelry. Symbolically, they provide a spectrum of meanings, from protection and wisdom to transformation and clarity. This variety ensures that every individual born in December can find a gemstone that resonates with their personal style and values, making these icy-blue stones enduring symbols of the month’s festive and enchanting spirit.