December is unique in the world of birthstones, holding the distinction of having four officially recognized gemstones. This abundance reflects the month's cultural and geological richness, offering a palette of cool blues and greens that capture the essence of winter. The four December birthstones—Turquoise, Tanzanite, Zircon, and Blue Topaz—each possess distinct histories, properties, and symbolic meanings. While they share a common color spectrum, they differ significantly in hardness, rarity, market value, and formation. This article explores the origins, gemological properties, historical lore, and practical considerations for each of these remarkable gems, providing a detailed guide for enthusiasts, collectors, and jewelry buyers.
History and Lore
The historical significance of December's birthstones spans millennia, from ancient civilizations to modern markets. Turquoise is arguably the oldest of the four, with a history stretching back over 3,000 years. It was a favored gem for amulets in ancient Egypt and Persia, prized for its perceived protective powers. The stone's name itself derives from its journey through gem markets in Constantinople, Turkey, en route to Europe. Historically, turquoise was believed to warn its wearer of impending illness or danger by changing color, and it was a symbol of friendship and marital fidelity. In Tibetan culture, turquoise was considered a stone of fortune, health, and success, and was even used as currency. Native American tribes of the Southwest associated the gem with youth and strength, while ancient Incas and Mayas offered it as gifts to their gods.
Zircon has a similarly ancient pedigree. Sources indicate it was used as an amulet against the Black Death plague in Europe, highlighting its historical role as a protective talisman. In India, it was believed that zircon had greater potency if set in gold. This gem, often mistaken for diamond due to its brilliance, has been valued for centuries for its sparkle and durability.
Tanzanite, by contrast, is a product of the modern era. Discovered in 1967 in the Merelani Hills of Tanzania, it was named and popularized by Tiffany & Co. in 1968. Its official recognition as a December birthstone came much later, in 2002, when the American Gem Trade Association added it to the list. This addition was driven by a desire to highlight rare gems and expand consumer options. Its rapid rise to fame was bolstered by celebrity endorsements, with figures like Anne Hathaway, Cate Blanchett, and Sarah Jessica Parker photographed wearing tanzanite jewelry. The gem symbolizes transformation, new beginnings, and heightened intuition, resonating with modern spirituality and self-growth.
Blue Topaz is a popular modern option. While topaz itself has been known since antiquity, the vibrant blue varieties commonly seen in jewelry today are the result of modern treatment processes. Its inclusion in December's birthstone list, as noted by sources like the American Gem Society, reflects the industry's trend toward offering more affordable and readily available alternatives. The expansion of the birthstone list over time, beginning in 1912 with the American National Retail Jeweler's Association, was driven by practical considerations such as availability, durability, and cost, as well as evolving cultural and commercial trends.
Geological Formation and Sources
The geographic origins of these gemstones are as diverse as their histories. Turquoise is a secondary mineral formed by the interaction of water with pre-existing minerals containing copper and aluminum. Historically, it was found in Persia and along the Sinai Peninsula. While specific modern mining locations are not detailed in the provided chunks, its formation is linked to arid regions where such geological conditions occur.
Zircon is a zirconium silicate mineral found in a variety of geological environments. Major gem-quality zircon production is concentrated in Australia and South Africa, which together account for approximately 70% of the world's zircon gemstones. It is also found in Sri Lanka, India, and other locations.
Tanzanite's origin story is uniquely specific. It is found in only one location in the entire world: the Merelani Hills near Mount Kilimanjaro in Tanzania. This extreme rarity is a key factor in its value and appeal. The gem is not available for recreational rockhounding, and its scarcity makes it a prized possession.
Blue Topaz is more widely available. Topaz crystals are typically found in pegmatites and hydrothermal veins. Major sources include Brazil, Nigeria, and Sri Lanka. The blue color in most commercial blue topaz is achieved through irradiation and heat treatment of colorless or pale yellow topaz crystals, a standard industry practice.
Gemological Properties
The four December birthstones vary significantly in their physical and optical properties, which directly influence their durability, appearance, and care requirements.
Turquoise is an opaque, cryptocrystalline mineral with a hardness of 5 to 6 on the Mohs scale, making it relatively soft and susceptible to scratching and chemical damage. Its color ranges from blue to green, often with a characteristic matrix (veining) from the host rock. It has a specific gravity of 2.6 to 2.9 and is typically cut into cabochons to highlight its color and texture.
Zircon is one of the hardest gemstones, with a Mohs hardness of 7 to 7.5. This makes it durable and suitable for everyday jewelry. It has a high refractive index (1.92-1.98) and strong dispersion (0.039), giving it exceptional brilliance and fire, often compared to diamond. Zircon occurs in a variety of colors, with blue zircon being a popular choice for December. It is pleochroic, showing different colors when viewed from different crystal directions.
Tanzanite is a variety of the mineral zoisite and has a Mohs hardness of 6 to 7. It is trichroic, meaning it can display three different colors—typically blue, violet, and burgundy—depending on the viewing angle and lighting. Under standard artificial light, it often appears violet, while it shows a rich blue under fluorescent light. Most tanzanite on the market has been heat-treated to remove brownish hues and enhance its blue and violet colors. It has a specific gravity of 3.35 and a refractive index of 1.69-1.70.
Blue Topaz is a silicate mineral with a Mohs hardness of 8, making it one of the hardest and most durable options for December. It is typically transparent and is cut into faceted gems. The blue color is usually the result of treatment, and the stone has a specific gravity of 3.49 to 3.57 and a refractive index of 1.61-1.63.
| Gemstone | Mineral Family | Mohs Hardness | Typical Colors | Key Distinguishing Feature |
|---|---|---|---|---|
| Turquoise | Phosphate | 5 - 6 | Blue to Green | Opaque, often with a matrix |
| Zircon | Zirconium Silicate | 7 - 7.5 | Various (Blue popular) | High brilliance and fire |
| Tanzanite | Zoisite | 6 - 7 | Blue-Violet, Burgundy | Trichroic (3-color change) |
| Blue Topaz | Silicate | 8 | Blue (treated) | High durability, transparent |
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, each December gemstone carries a wealth of symbolic meaning and metaphysical lore, much of which is rooted in ancient tradition.
Turquoise has long been a stone of protection, healing, and peace. It was believed to guard against danger, bring good fortune, and preserve friendship when given as a gift. Its association with the sky and water made it a symbol of tranquility and spiritual grounding. In Tibetan culture, it was linked to fortune, health, and success.
Zircon is often associated with wisdom, honor, and purity. Historically, it was used as an amulet for protection against plague and was believed to promote prosperity when set in gold. Its diamond-like sparkle has led to associations with clarity of thought and spiritual light.
Tanzanite, as a modern discovery, is linked to transformation and new beginnings. It is said to enhance intuition, promote spiritual growth, and help in navigating change. Its unique color shift is seen as a metaphor for seeing different perspectives and embracing personal evolution.
Blue Topaz is traditionally associated with calm, clarity, and communication. It is believed to soothe emotions, reduce stress, and promote honest expression. Its cool blue hue is linked to the throat chakra in modern metaphysical practices, emphasizing its connection to truthful speech.
Care and Cleaning
The diverse properties of these gemstones necessitate different approaches to care and cleaning.
Turquoise, with its relatively low hardness and porosity, requires gentle handling. It should be protected from chemicals, including perfumes, lotions, and household cleaners, which can damage its surface and cause discoloration. Cleaning should be done with a soft, dry cloth. Avoid ultrasonic cleaners and steam cleaning. It is best stored separately to prevent scratching.
Zircon is relatively hard but can be brittle due to its crystal structure. It is important to protect it from sharp blows. It can be cleaned with warm soapy water and a soft brush. Ultrasonic cleaners are generally safe, but steam cleaning should be avoided due to the risk of thermal shock. Zircon is also pleochroic, so it's important to consider the stone's orientation when setting it in jewelry to display its best color.
Tanzanite is softer than zircon and topaz, so it should be handled with care to avoid scratches and chips. It is sensitive to heat and sudden temperature changes, so it should not be exposed to high heat or steam. Cleaning with warm soapy water and a soft brush is recommended. Ultrasonic cleaners should be avoided, as vibrations can cause internal fractures. Due to its trichroism, the cut of tanzanite is critical to maximize its color play.
Blue Topaz is the most durable of the four, with a hardness of 8. It can withstand more rigorous cleaning methods. Warm soapy water and a soft brush are effective for routine cleaning. Ultrasonic cleaners are generally safe, but steam cleaning should be approached with caution, especially for stones that may have been fracture-filled. Its durability makes it an excellent choice for rings and bracelets that see daily wear.
Conclusion
The four birthstones of December—Turquoise, Tanzanite, Zircon, and Blue Topaz—offer a remarkable range of choices for those born in the final month of the year. From the ancient protective talisman of turquoise to the fiery brilliance of zircon, the transformative beauty of tanzanite, and the durable clarity of blue topaz, each gemstone tells a unique story of geology, history, and human belief. Their selection reflects a balance of personal preference, practical considerations like durability and budget, and a connection to the symbolic meanings that have been attached to these stones for centuries. Whether chosen for their beauty, their lore, or their symbolic significance, these gems provide a fittingly brilliant and diverse palette for December birthdays.