December, the final month of the year, is symbolically rich with celebration, reflection, and anticipation. In the world of gemology, it is equally distinguished by the diversity of its birthstones. Those born in December are fortunate to have a choice of four gemstones: turquoise, tanzanite, blue zircon, and blue topaz. Each of these stones carries a unique history, a set of gemological properties, and cultural significance that has evolved over time. This article explores the origins, characteristics, uses, and symbolism of these December birthstones, drawing from a variety of authoritative and historical sources.
History and Lore of the December Birthstones
The tradition of assigning birthstones to specific months is ancient, but the modern list has undergone several revisions. The earliest known lists, influenced by Biblical references to the High Priest’s breastplate, did not assign turquoise, tanzanite, or zircon to December. Instead, ruby was once considered the December birthstone. Over time, as gemology evolved and new stones were discovered or gained popularity, the December birthstone list was updated.
The first recorded assignment of turquoise as a December birthstone dates back to 1870, when it was included in Tiffany & Co.’s “Gregorian Birthstone Poems.” By 1912, the National Association of Jewellers (now Jewellers of America) recognized turquoise as the primary December birthstone and listed lapis lazuli as an alternative. In 1952, zircon was added to the list by the Jewelry Industry Council of America. Finally, in 2002, tanzanite—discovered as recently as the 1960s—was officially included, reflecting the evolving nature of birthstone traditions.
The inclusion of multiple stones for December is a practical response to the diversity of gemstone availability and affordability. As one source notes, having multiple birthstones allows for more accessible options in addition to the traditional or more expensive ones. This flexibility has made December’s birthstone selection particularly dynamic, with each stone adding its own dimension to the month’s symbolic meaning.
Geological Formation and Sources
Turquoise
Turquoise is a hydrated phosphate of aluminum and copper, forming in arid environments where copper deposits are exposed to weathering and oxidation. The process begins when rainwater or melting snow percolates through copper-rich rock, creating an acidic solution that carries dissolved copper. This solution then interacts with aluminum and potassium in surrounding rocks, leading to the precipitation of turquoise in cavities within volcanic or sedimentary rock.
Geographically, turquoise is primarily found in arid regions with suitable geological conditions. Major sources include the American Southwest (Arizona, Nevada, New Mexico), as well as Egypt, Iran, China, and Mexico. The American Southwest is particularly famous for its high-quality turquoise, with mines like the Cerrillos Mine in New Mexico and the Kingman Mine in Arizona producing some of the most coveted turquoise in the world.
The stone’s hardness on the Mohs scale ranges from 5 to 6, making it relatively soft and prone to scratching or breaking. It is also porous and can be easily discolored by oils, pigments, or changes in its water content. This necessitates careful handling and specific cleaning methods to preserve its appearance.
Tanzanite
Tanzanite is a rare gemstone discovered in the 1960s near Mount Kilimanjaro in Tanzania. It is a variety of the mineral zoisite and is prized for its vivid blue and purple colors. Tanzanite exhibits strong pleochroism, meaning it appears different in color depending on the viewing angle and lighting conditions. Most tanzanite gemstones display a combination of blue and purple hues, which can be enhanced through heat treatment.
The geological rarity of tanzanite is a key factor in its value. It is found only in a small region of Tanzania, and its formation is linked to specific tectonic and mineralogical conditions that occurred millions of years ago. This limited geographic source makes tanzanite one of the most exclusive gemstones in the world.
Blue Zircon
Blue zircon is a natural gemstone that has been used as a diamond substitute for centuries due to its high refractive index and brilliance. It is found in several parts of the world, including Thailand, Cambodia, and Vietnam. Zircon exists in a variety of colors, including colorless, yellow, brown, and red, but the blue variety is particularly popular as a December birthstone.
The blue color in zircon is achieved through heat treatment, which removes the original coloration and produces a pastel blue hue. Some zircon specimens contain trace amounts of radioactive elements like uranium and thorium, which have been instrumental in the development of radiometric dating techniques. In fact, some zircon crystals have been dated to be over 4.4 billion years old, making them among the oldest minerals on Earth.
Blue Topaz
Blue topaz is a popular and affordable alternative to the more expensive zircon and tanzanite. It is available in large sizes and is widely used in jewelry. The blue color in topaz is typically the result of irradiation and heat treatment, which alter the stone’s internal structure to produce the desired hue.
Blue topaz is found in several countries, including Brazil, the United States, and Nigeria. It has a higher hardness on the Mohs scale (8) compared to turquoise or zircon, making it more durable and suitable for everyday wear. Its affordability and availability have made it a popular choice for modern December birthstone jewelry.
Gemological Properties
To better understand the unique qualities of each December birthstone, it is helpful to compare their gemological properties. The following table summarizes key characteristics such as hardness, refractive index, and typical treatments:
| Gemstone | Hardness (Mohs) | Color | Refractive Index | Common Treatments | Typical Use in Jewelry |
|---|---|---|---|---|---|
| Turquoise | 5–6 | Blue to green | 1.61–1.65 | Stabilization, dyeing | Cabochons, inlays |
| Tanzanite | 6–7 | Blue, violet | 1.69–1.70 | Heat treatment | Faceted stones |
| Blue Zircon | 6–7.5 | Blue | 1.92–2.00 | Heat treatment | Faceted stones |
| Blue Topaz | 8 | Blue | 1.62–1.64 | Irradiation, heat treatment | Faceted stones |
This table highlights the distinct properties of each gemstone. Turquoise, being the softest, is best suited for protective settings, while blue topaz, with its higher hardness and durability, is ideal for everyday wear. Tanzanite and blue zircon fall in between, offering a balance of brilliance and resilience.
Symbolism and Metaphysical Beliefs
The December birthstones have long been associated with various symbolic and metaphysical properties, though these beliefs vary across cultures and historical periods.
Turquoise
Turquoise has been revered for millennia in ancient civilizations such as Egypt, Persia, and the American Southwest. It was considered a sacred stone with protective and healing properties. In Native American cultures, turquoise was believed to bring good fortune and was often used in ceremonial regalia and jewelry. In medieval Europe, it was associated with royalty and was worn as a symbol of nobility and wisdom.
Modern metaphysical beliefs often attribute calming and balancing properties to turquoise. It is said to promote serenity, communication, and emotional stability. Some sources suggest that turquoise can enhance spiritual awareness and facilitate healing, particularly for throat and respiratory ailments.
Tanzanite
As the newest of the December birthstones, tanzanite has not had as long to accumulate a rich history of symbolic associations. However, it is often linked to intuition and emotional healing. Its deep blue and purple hues are thought to resonate with the third eye and crown chakras, promoting spiritual insight and connection to higher consciousness.
Tanzanite is also associated with transformation and renewal, making it an apt symbol for the month of December, which marks the end of one year and the beginning of another. Its rarity and exclusivity are also seen as metaphors for unique personal journeys and self-discovery.
Blue Zircon
Zircon has a long history of use in jewelry and has been valued for its brilliance and fire. In ancient times, it was sometimes used as a diamond substitute. Some cultures believed that zircon had protective properties, particularly when worn during travel or in times of danger.
In modern gemstone lore, blue zircon is associated with wisdom, truth, and clarity. It is thought to enhance mental focus and promote emotional healing. Some sources suggest that zircon can help in overcoming grief and fostering a sense of inner peace.
Blue Topaz
Blue topaz is often associated with calmness, serenity, and emotional balance. It is believed to have a soothing effect on the mind and is used in meditation and healing practices. Some traditions associate it with the throat chakra, enhancing communication and self-expression.
Blue topaz is also linked to love and friendship, making it a popular choice for engagement rings and anniversary gifts. Its affordability and availability have made it a favorite among those who seek meaningful yet accessible gemstone jewelry.
Care and Cleaning of December Birthstones
Proper care is essential for preserving the beauty and longevity of December birthstone jewelry. Each stone has different requirements based on its hardness, porosity, and sensitivity to chemicals and heat.
Turquoise
Turquoise is one of the more delicate December birthstones and requires careful handling. It is not recommended for use in immersion cleaning methods, as it is porous and can absorb chemicals or lose its color when exposed to water or solvents. Instead, it should be cleaned with a soft cloth and mild soap. It should also be stored in a cool, dry place to prevent discoloration or dehydration.
Tanzanite
Tanzanite can be cleaned using standard jewelry cleaning solutions, but it is advisable to avoid exposure to extreme heat or direct sunlight for extended periods. Heat can cause the color to fade, and prolonged exposure to sunlight can dull its brilliance. Tanzanite should be stored separately from harder gemstones to prevent scratching.
Blue Zircon
Blue zircon can be cleaned with a soft brush and mild soap. It is relatively durable but should be kept away from harsh chemicals and ultrasonic cleaners, which can damage its surface. Like tanzanite, it should be stored in a cool, dry place to avoid discoloration.
Blue Topaz
Blue topaz is one of the most durable December birthstones, with a hardness of 8 on the Mohs scale. It can be cleaned using ultrasonic cleaners and standard jewelry solutions. However, it should be protected from sudden temperature changes, which can cause internal fractures.
Conclusion
The December birthstones—turquoise, tanzanite, blue zircon, and blue topaz—offer a rich tapestry of history, symbolism, and gemological significance. From the ancient reverence for turquoise in the American Southwest to the modern allure of tanzanite discovered in the 1960s, each stone tells a story of cultural evolution and natural beauty. Their diverse properties make them suitable for a wide range of jewelry styles, from vintage and antique pieces to contemporary designs.
Understanding the geological origins, gemological characteristics, and cultural significance of these stones allows for a deeper appreciation of their role in both personal adornment and historical tradition. Whether chosen for their beauty, durability, or symbolic meaning, December birthstones continue to captivate gemstone enthusiasts and jewelry lovers alike.