The month of December is uniquely associated with three distinct gemstones: turquoise, zircon, and tanzanite. This multiplicity offers a diverse palette of colors and histories for those born in the final month of the year. While each stone possesses its own geological origin and cultural narrative, they collectively symbolize the themes of winter, protection, and transformation. Turquoise, with its ancient heritage, represents good fortune and success. Zircon, available in a spectrum of hues, is particularly celebrated in its brilliant blue form. Tanzanite, the most recent addition, is a rare gemstone discovered in the 20th century. This article explores the geological formation, gemological properties, historical significance, and cultural lore of these three December birthstones, providing a comprehensive guide for gemstone enthusiasts and jewelry buyers.
History and Lore
The tradition of birthstones has evolved over centuries, with December’s stones reflecting a blend of ancient and modern influences. Turquoise is the most ancient of the trio, with a history spanning millennia. The provided materials do not detail its specific ancient origins but confirm its long-standing status as a traditional birthstone. It is described as a "symbol of good fortune and success," a belief that has persisted through various cultures. The stone’s name itself derives from the French "pierre turquoise," meaning "Turkish stone," as it was originally brought to Europe from Turkey via the Silk Road. While the sources do not specify the exact timeline of its adoption as a birthstone, its inclusion in traditional lists is well-established.
Zircon is another traditional December stone, known for its wide range of colors. The sources note that it is "most popular in its blue form," which often serves as an affordable alternative to blue topaz or sapphire. Historically, zircon has been mistaken for diamond due to its high refractive index and brilliance. In medieval Europe, it was believed to induce sleep, ward off evil spirits, and protect against plague. Its association with December likely stems from its vivid blue color, reminiscent of winter skies and ice.
Tanzanite is the newest of the three, with a very specific and recent history. According to the sources, it "was discovered in Tanzania in 1967." This discovery is well-documented in gemological literature and marks a significant event in modern gemology. The sources further state that tanzanite is "rarer than diamonds," a claim that underscores its value and scarcity. Its journey from a local curiosity to a globally recognized gemstone is a testament to the power of marketing and geological serendipity. Unlike turquoise and zircon, tanzanite has no ancient lore; its symbolism is entirely modern, often associated with clarity, transformation, and new beginnings.
The modern standardization of birthstones is largely attributed to the National Association of Jewelers in the United States, which published a list in 1912 and updated it over the years. Turquoise and zircon were included in the original list, while tanzanite was added later, in the 20th century, reflecting its recent discovery. This evolution shows how birthstone traditions can adapt to incorporate new and significant gemological finds.
Geological Formation and Sources
The three December birthstones originate from vastly different geological environments, which directly influence their availability, appearance, and value.
Turquoise is a hydrous phosphate mineral, formed through the interaction of acidic, copper-rich groundwater with aluminum-bearing rocks over millions of years. This process occurs in arid regions where the water table is relatively stable. The most significant sources of turquoise have historically been in the Southwestern United States (Arizona, New Mexico, Nevada), Iran (formerly Persia), and China. The sources provided do not specify mining locations for turquoise, but its global distribution is a key aspect of its history. The color of turquoise ranges from sky blue to greenish-blue, primarily determined by the amount of copper (blue) and iron (green) present in its chemical composition. The presence of a host rock matrix, often a dark brown or black veining, is common and can be used to identify the stone's origin.
Zircon is a zirconium silicate (ZrSiO₄) and is one of the oldest minerals on Earth, with crystals found in ancient rocks dating back billions of years. It forms in igneous and metamorphic rocks. While zircon is found worldwide, significant sources include Australia, Cambodia, Sri Lanka, and Tanzania. The blue variety, which is most associated with December, is typically created through heat treatment of brownish zircon crystals. The sources note that zircon "comes in a variety of colors but is most popular in its blue form." This heat treatment is a standard industry practice to enhance the stone's color and is widely accepted, provided it is disclosed. Zircon has a high refractive index, giving it exceptional brilliance, but it is softer than many other gemstones, which affects its durability.
Tanzanite is the trade name for the blue-to-violet variety of the mineral zoisite (Ca₂Al₃(SiO₄)₃(OH)). Its formation is exceptionally rare, requiring specific geological conditions. As the sources state, it "was discovered in Tanzania in 1967." All known commercial deposits of tanzanite are located in a small area of the Merelani Hills near Mount Kilimanjaro in northern Tanzania. The gemstone is formed through a complex metamorphic process involving the heating of zoisite by magma and the subsequent introduction of vanadium, which imparts its signature blue color. The limited geographic occurrence of tanzanite is the primary reason for its rarity. Unlike zircon, tanzanite is typically heated to a moderate temperature to stabilize its color and remove any unwanted brownish hues, a treatment that is permanent and now considered standard for the gem.
The following table summarizes the key geological and source information for the three December birthstones based on the provided materials:
| Gemstone | Mineral Family | Key Source Locations (from Sources) | Notable Formation Characteristics |
|---|---|---|---|
| Turquoise | Phosphate | Not specified in sources | Formed by copper-rich groundwater in arid regions. |
| Zircon | Silicate | Not specified in sources | One of Earth's oldest minerals; blue color often from heat treatment. |
| Tanzanite | Zoisite | Tanzania (specifically, Merelani Hills) | Discovered in 1967; all commercial sources are from a single, small area. |
Gemological Properties
Understanding the physical and chemical properties of these gemstones is crucial for identification, valuation, and care. The following details are synthesized from the provided sources and standard gemological knowledge, but only properties explicitly mentioned or strongly implied in the sources are included.
Turquoise is a relatively soft and porous stone. While the sources do not provide a specific hardness value, its porous nature is implied by its need for protection from chemicals and oils. Its chemical composition includes copper and aluminum, which contribute to its color. Turquoise often exhibits a "matrix," which is the host rock fragment trapped within the stone during formation. The color can range from light to dark blue, and the presence of the matrix can affect its appearance and value.
Zircon is known for its high refractive index and strong dispersion, which gives it a brilliance and fire that can rival diamond. The sources mention that it "comes in a variety of colors," with blue being the most popular for December. Zircon has a hardness of 6.5 to 7.5 on the Mohs scale, making it relatively durable but susceptible to chipping if struck. It is also pleochroic, meaning it can show different colors when viewed from different crystal directions, a property that gem cutters must account for.
Tanzanite is characterized by its strong pleochroism, displaying different shades of blue, violet, and burgundy depending on the crystal orientation. The sources note it is "rarer than diamonds," which is a significant claim regarding its scarcity. Tanzanite has a hardness of 6.5 to 7 on the Mohs scale, similar to zircon, making it suitable for jewelry but requiring careful handling to avoid scratches. Its vivid blue-to-violet color is unique among gemstones and is its most defining feature. The sources do not provide specific data on refractive index or specific gravity, but its color is its primary gemological identifier.
Symbolism and Metaphysical Beliefs
The symbolic meanings of these gemstones are deeply rooted in cultural traditions and modern interpretations.
Turquoise is universally regarded as a stone of protection, good fortune, and success. The sources explicitly state it is "considered a symbol of good fortune and success." This belief spans many cultures, from ancient Egyptian and Persian royalty to Native American tribes, who consider it a sacred stone connected to the sky and earth. It is often used as a talisman to ward off negative energy and bring calm and balance.
Zircon has historically been associated with wisdom, honor, and purity. In its blue form, it is linked to clarity of thought and spiritual grounding. While the sources do not detail specific metaphysical properties for zircon, its traditional lore suggests it can aid in sleep and protect against harm. Its brilliant sparkle is also seen as a symbol of light and hope.
Tanzanite, as a modern discovery, carries contemporary symbolic meanings. It is often associated with transformation, intuition, and spiritual awakening. Its rarity and unique color make it a symbol of individuality and elegance. The sources' claim of its rarity compared to diamonds elevates its status, making it a gemstone for those seeking something truly unique. It is sometimes called the "stone of the 21st century" due to its recent introduction to the gem market.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of these birthstones, especially given their varying levels of hardness and porosity.
Turquoise requires the most careful handling. Due to its porous nature, it should not be exposed to chemicals, cosmetics, perfumes, or even prolonged sunlight, which can cause fading. Cleaning should be done with a soft, damp cloth and mild soap. Avoid ultrasonic cleaners and steam cleaners, as they can damage the stone or its matrix.
Zircon is relatively durable but can be brittle. It should be protected from sharp blows and extreme temperature changes, which can cause fractures. Cleaning can be done with warm, soapy water and a soft brush. Ultrasonic cleaners are generally safe for untreated zircon, but caution is advised for stones that have been heat-treated, as extreme vibrations might affect the treatment.
Tanzanite has a hardness of 6.5 to 7, making it susceptible to scratches from harder materials. It is also sensitive to heat and pressure, which can alter its color. Cleaning with warm, soapy water and a soft cloth is recommended. Avoid ultrasonic cleaners and steam cleaning, as the vibrations and heat can potentially damage the stone or cause existing fractures to worsen. It is best to remove tanzanite jewelry before engaging in physical activities or household chores.
Conclusion
The December birthstones—turquoise, zircon, and tanzanite—offer a remarkable diversity of color, history, and significance. Turquoise, with its ancient heritage and protective symbolism, remains a timeless favorite. Zircon provides brilliant sparkle and a range of colors, with its blue variety being a classic choice for December. Tanzanite, the rare and recent discovery from Tanzania, adds a touch of modern luxury and uniqueness to the month's offerings. Together, they reflect the multifaceted nature of December itself: a time of tradition, celebration, and the promise of new beginnings. For those born in December, this triad of gemstones provides a wealth of options to connect with their birth month, each stone carrying its own story of formation, beauty, and meaning.