For those born in the final month of the year, the birthstone selection is uniquely abundant. December is associated with four distinct gemstones: Turquoise, Tanzanite, Blue Topaz, and Zircon. This quartet offers a remarkable spectrum of colors, histories, and properties, from the ancient, earthy tones of turquoise to the vibrant, modern brilliance of blue topaz. Each stone carries its own narrative, rooted in geology, history, and culture, providing a rich palette of choices for jewelry enthusiasts and collectors. This guide delves into the origins, characteristics, and significance of each December birthstone, drawing upon authoritative gemological knowledge to illuminate their enduring appeal.
History and Lore
The historical journey of December's birthstones spans millennia, with each stone forging a unique path through human civilization. Turquoise holds the distinction of being one of the oldest known gemstones in human adornment. Its use dates back over 6,000 years, with archaeological evidence pointing to ancient Egypt, where it was prized by royalty, including King Tutankhamun. The ancient Egyptians believed turquoise offered protection and good health, often burying it with their dead to safeguard the soul in the afterlife. Similarly, many Native American cultures of the American Southwest have revered turquoise for centuries, viewing it as a sacred stone that connects the wearer to the earth and sky, symbolizing wisdom, tranquility, and friendship.
Zircon has an equally long but often confused history. The term "zircon" is derived from the Arabic word "zargun," meaning "gold-colored," reflecting its common yellow-brown hues. For centuries, zircon was mistaken for other gemstones, notably diamond, due to its high refractive index and fiery brilliance. In medieval Europe, zircon was believed to promote honor, purity, and prosperity. It was also thought to induce sleep and ward off evil spirits, making it a popular talisman. However, its history is frequently overshadowed by the confusion with synthetic cubic zirconia, a later diamond simulant, leading to a common misconception that zircon itself is an artificial material.
Tanzanite is the newest addition to the December birthstone family, with its discovery occurring in the late 20th century. First found in the Merelani Hills of Tanzania in 1967, its initial identification was met with excitement. The gem's alluring blue-violet hue, which exhibits pleochroism—showing different colors from different angles—was unlike any other known gemstone. It was initially named "blue zoisite" but was later renamed "tanzanite" in honor of its exclusive origin. The Tiffany & Co. jewelry house famously launched tanzanite in 1968, marketing it as a rare and precious gem, which cemented its status as a modern luxury stone.
Blue Topaz, while not as historically ancient as turquoise, has a notable past. Natural blue topaz is relatively rare, but the gemstone's popularity surged in the 20th century with the development of treatment processes that could turn abundant colorless topaz into a vibrant blue. Its association with December is a more modern development, gaining mainstream recognition in the late 20th and early 21st centuries. It is often cited as a symbol of communication and clarity, building on the general lore of topaz as a stone of calm and strength.
Geological Formation and Sources
The geographic origins of these birthstones are as diverse as their appearances, with specific regions known for producing the finest qualities of each gem.
Turquoise forms in arid regions where water containing copper and aluminum interacts with host rocks over long periods. This process creates secondary mineral deposits in veins and nodules. The most significant sources include the southwestern United States, particularly Arizona and New Mexico, where turquoise is often found with a distinctive matrix (the host rock). Other major sources are Iran (known for its pure, sky-blue "Persian turquoise"), Egypt, China, Mexico, and parts of Central Asia and Africa. The specific geological conditions, including the presence of copper-rich formations and unique weather patterns, contribute to the stone's characteristic color and matrix patterns.
Zircon is a mineral that crystallizes in igneous and metamorphic rocks. It is a common accessory mineral in many rock types but gem-quality zircon is much rarer. Major sources for gem zircon include Australia (which produces a wide range of colors, including the prized "hyacinth" or orange-brown variety), Cambodia, Sri Lanka, Thailand, and Myanmar. The stone's formation often occurs in granitic pegmatites or high-temperature metamorphic environments, where it can grow to substantial sizes, though facetable crystals are less common.
Tanzanite is unique in that it is found in only one location in the world: the Merelani Hills near Mount Kilimanjaro in Tanzania. The gemstone is a variety of the mineral zoisite, and its formation is linked to the tectonic and metamorphic events associated with the East African Rift. The specific geological conditions in this small area have produced the only known commercial deposit of tanzanite, making it exceptionally rare. The mining area is divided into four blocks, with Block C being the most famous for producing high-quality material.
Blue Topaz is a silicate mineral that typically forms in large, colorless crystals in pegmatite veins and high-temperature hydrothermal environments. While topaz occurs in many locations worldwide, the vast majority of blue topaz in the market today is the result of treating colorless or pale yellow topaz. Natural blue topaz is rare. Major sources for the base material include Brazil, Nigeria, Sri Lanka, and Mexico. The treatment process, which involves irradiation followed by controlled heating, is a standard industry practice that produces stable, vivid blue colors like Sky Blue, Swiss Blue, and London Blue.
Gemological Properties
Understanding the physical and chemical properties of each gemstone is essential for appreciating its value, durability, and care requirements. The following table summarizes key gemological data for the four December birthstones, based on established industry standards as reflected in the provided materials.
| Property | Turquoise | Tanzanite | Blue Topaz | Zircon |
|---|---|---|---|---|
| Mineral Family | Phosphate (Hydrated copper aluminum phosphate) | Zoisite (a variety of epidote) | Silicate (Fluorine aluminum silicate) | Silicate (Zirconium silicate) |
| Chemical Formula | CuAl₆(PO₄)₄(OH)₈·4H₂O | Ca₂Al₃(SiO₄)₃(OH) | Al₂SiO₄(F,OH)₂ | ZrSiO₄ |
| Crystal System | Triclinic | Orthorhombic | Orthorhombic | Tetragonal |
| Hardness (Mohs Scale) | 5 - 6 | 6.5 - 7 | 8 | 6.5 - 7.5 |
| Refractive Index | 1.610 - 1.650 | 1.691 - 1.700 | 1.609 - 1.629 | 1.92 - 2.01 |
| Specific Gravity | 2.60 - 2.90 | 3.35 | 3.53 | 4.6 - 4.7 |
| Pleochroism | None | Strong (blue, violet, burgundy) | None | None |
| Transparency | Opaque to translucent | Transparent to translucent | Transparent | Transparent |
| Notable Features | Often contains a matrix; porous; color can fade with prolonged exposure to chemicals, heat, or sunlight. | Known for its strong pleochroism; often heat-treated to improve color stability and remove brown undertones. | Most blue topaz is irradiation-treated; natural blue topaz is extremely rare. | High refractive index and brilliance; can be heat-treated to improve color; some varieties (e.g., "Matura" blue) are produced by heating brown zircon. |
Turquoise is prized for its opaque to translucent sky-blue to greenish-blue color, which can be uniform or interrupted by a darker, web-like matrix. Its hardness (5-6) makes it relatively soft and susceptible to scratching. It is also porous, which means it can absorb chemicals, oils, and lotions, potentially leading to discoloration or damage. The color of turquoise is derived from copper, while the matrix color comes from other minerals in the host rock.
Tanzanite is valued for its transparency and vivid blue-violet hue. Its most defining characteristic is pleochroism, where a single crystal can display three different colors: blue, violet, and burgundy, depending on the viewing angle. Gem cutters must orient the stone carefully to showcase the desirable blue-violet color. Most tanzanite on the market has been heat-treated to remove brownish undertones and enhance its blue color; this treatment is permanent and widely accepted. With a hardness of 6.5 to 7, it is durable enough for most jewelry but requires care to avoid sharp blows.
Blue Topaz is known for its excellent clarity and vibrant blue color, which is almost always the result of treatment. Natural blue topaz is exceedingly rare. The gem has a hardness of 8 on the Mohs scale, making it very resistant to scratching and ideal for rings and daily-wear jewelry. Its high transparency and strong luster contribute to its popularity. The color can range from pale Sky Blue to deep London Blue, with the intensity often related to the treatment process and the size of the stone.
Zircon is one of the oldest minerals on Earth and is renowned for its exceptional brilliance and fire, which rival that of diamond due to its high refractive index. While naturally occurring in a wide spectrum of colors (including brown, green, red, and yellow), the blue variety is a popular December birthstone. Most blue zircon is produced by heating brown zircon at high temperatures, a treatment that is permanent. Zircon has a hardness of 6.5 to 7.5, making it reasonably durable, though it can be brittle due to its tetragonal crystal structure and perfect cleavage in one direction, requiring careful cutting and setting.
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, December's birthstones are steeped in symbolism and metaphysical lore, offering wearers connections to various cultural and spiritual traditions.
Turquoise is perhaps the most symbolically rich of the four. It is universally associated with protection, healing, and good fortune. Ancient cultures believed it could deflect negative energy and physical harm, such as falls. In metaphysical circles, turquoise is linked to the Throat Chakra (for communication and self-expression) and the Heart Chakra (for love and compassion). It is said to promote emotional balance, serenity, and wisdom, and is often used as a talisman for travelers and those seeking peace.
Tanzanite, as a relatively new discovery, has developed modern metaphysical associations. It is often called the "stone of transformation," believed to facilitate a higher consciousness, intuition, and spiritual awakening. Its pleochroic nature is thought to represent the ability to see multiple perspectives. It is associated with the Crown and Throat Chakras, aiding in clear communication and the expression of one's truth. Some believe it can help alleviate stress and promote a sense of calm and mindfulness.
Blue Topaz is traditionally linked to communication, clarity of thought, and emotional balance. It is considered a stone of calm, patience, and truth. In crystal healing, blue topaz is associated with the Throat Chakra, believed to enhance honest self-expression and soothe the throat. It is also thought to bring joy, generosity, and abundance, and to aid in meditation by promoting a clear and tranquil mind.
Zircon has a long history of being associated with honor, purity, and prosperity. It was believed to promote restful sleep and ward off evil spirits. In modern metaphysical practices, zircon is thought to help with spiritual grounding and to connect the wearer to higher realms of consciousness. Different colors of zircon may carry slightly different meanings; for example, blue zircon is often linked to clarity, insight, and calm, while the fiery brilliance of the gem is said to inspire creativity and confidence.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of these gemstones, as their physical properties vary significantly.
Turquoise requires the most careful handling due to its softness (5-6 Mohs) and porosity. It should be cleaned only with a soft, dry cloth. Avoid ultrasonic cleaners, steam cleaners, chemicals, cosmetics, and prolonged exposure to sunlight or heat, as these can cause discoloration or cracking. It is best to put turquoise jewelry on after applying lotions and perfumes.
Tanzanite (hardness 6.5-7) is durable enough for most jewelry but should be protected from hard blows and sharp impacts. Clean it with warm water, mild soap, and a soft brush. Avoid ultrasonic cleaners and sudden temperature changes, which can cause fractures. It is advisable to remove tanzanite rings during strenuous activities.
Blue Topaz (hardness 8) is one of the more durable birthstones. It can be cleaned with warm soapy water and a soft brush. While it is resistant to chemicals, prolonged exposure to extreme heat or light could potentially affect the treated color, though this is rare with standard jewelry care. Ultrasonic cleaners are generally safe, but it's always best to consult a jeweler.
Zircon (hardness 6.5-7.5) is relatively hard but has perfect cleavage, meaning it can split along certain planes if struck with sufficient force. It should be handled with care to avoid knocks. Clean with warm, soapy water and a soft brush. Avoid ultrasonic cleaners and sudden temperature changes, as these can stress the stone. Due to its brittleness, zircon is often set in protective settings like bezels for rings.
Conclusion
The December birthstones—Turquoise, Tanzanite, Blue Topaz, and Zircon—collectively offer a stunning array of choices that cater to diverse tastes, budgets, and styles. From the ancient, protective talisman of turquoise to the modern, transformative allure of tanzanite, each stone provides a unique link to the natural world and human history. Their varied gemological properties dictate specific care requirements, but with proper maintenance, they can be cherished for generations. Whether drawn to the earthy matrix of turquoise, the pleochroic drama of tanzanite, the vibrant clarity of blue topaz, or the fiery brilliance of zircon, those born in December have access to a remarkable gemstone heritage that is as deep and varied as the winter month itself.