The final month of the year is uniquely represented by not one, but three distinct gemstones: Turquoise, Tanzanite, and Zircon. Each of these December birthstones offers a captivating variation on the color blue, allowing individuals born in this month to select a gem that best suits their personal style and preference. While they share a common color palette, their histories, geological origins, and gemological properties are remarkably diverse. This article delves into the detailed characteristics of each stone, exploring their journey from ancient mines to modern jewelry boxes, and providing a comprehensive guide for enthusiasts and collectors.
Historical Significance and Lore
The tradition of assigning specific gems to calendar months is a practice that has evolved over centuries. The modern birthstone chart, as we know it today, was largely standardized by the National Association of Jewelers (now Jewelers of America) in the United States. The list has undergone several revisions over time, with the most significant update to the December list occurring in 1952 when tanzanite was added. This addition marked the first change to the December birthstones in over 50 years, joining the established stones of turquoise and zircon.
Turquoise boasts one of the longest histories as a gemstone. It has been used for over 2000 years in the Southwestern United States, where Native American cultures created intricate beads, pendants, inlay work, and small sculptures from the stone. Its cultural importance remains strong in Southwestern regions today. The stone is traditionally associated with protection, wisdom, and good fortune, with its vibrant blue hue often symbolizing the sky and water.
Zircon is another gem with deep historical roots, valued for its brilliance and fire that rivals that of a diamond. While its specific historical narratives are less detailed in the provided sources compared to turquoise, its long-standing presence in jewelry attests to its enduring appeal.
Tanzanite is the youngest of the trio, a modern addition to the birthstone list. Its discovery and subsequent popularity are relatively recent, bringing a fresh, vivid blue to the December palette and offering a contemporary alternative to the more traditional stones.
Geological Formation and Global Sources
Understanding the origin of these gems provides insight into their unique characteristics and availability.
Turquoise is a mineral (a hydrated phosphate of copper and aluminum) that forms in arid regions where acidic, copper-rich water seeps through host rock and reacts with minerals containing aluminum and phosphorus. While the sources do not specify exact modern mining locations for turquoise, its historical use is firmly tied to the Southwestern United States, indicating a significant geological presence there. The stone is often found in nodules or veins within its host rock.
Zircon is a zirconium silicate mineral (ZrSiO₄) that forms in igneous and metamorphic rocks. It is one of the oldest minerals on Earth, with crystals found in ancient sediments. Zircon is mined in various locations worldwide, contributing to its wide availability in the gem market. The discovery of large deposits in Brazil has notably increased its supply, making it more accessible and affordable.
Tanzanite is a variety of the mineral zoisite, specifically the blue to violet form. It was first discovered in the Merelani Hills of northern Tanzania in the late 1960s, making it one of the few major gemstones found in a single geographic location. Its formation is linked to a unique geological event involving intense heat and pressure, which transformed the host rock and created the conditions for tanzanite to form. This limited source area contributes to its rarity and value.
Gemological Properties
Each December birthstone possesses a distinct set of physical and optical properties that define its durability, appearance, and care requirements. The following table summarizes key characteristics based on the provided sources.
| Gemstone | Chemical Composition | Mohs Hardness | Cleavage | Key Properties & Notes |
|---|---|---|---|---|
| Turquoise | Hydrated copper & aluminum phosphate | Low (not specified, but noted as easily scratched) | None | Opacity: Typically opaque. Color: Blue to blue-green to yellowish green; bright blue is most preferred. Cut: Usually cut into cabochons, often freeform. Affordability: Generally affordable; lab-created versions exist. |
| Zircon | Zirconium silicate (ZrSiO₄) | Not specified in sources, but generally 6.5-7.5 | None | Luster & Fire: Bright gem with high luster and colorful fire similar to a diamond. Color: Can be various colors; "blue zircon" is a specific type for December. Affordability: More affordable due to large deposits in Brazil. |
| Tanzanite | Calcium aluminum silicate (Zoisite variety) | Not specified in sources, but generally 6.5-7 | Perfect cleavage noted for tanzanite, meaning it will break easily if struck. | Color: Blue to violet. Transparency: Transparent. Rarity: Found only in Tanzania. Care: Requires careful handling due to perfect cleavage. |
Important Note on Durability: The sources highlight specific vulnerabilities for December's stones. Tanzanite has perfect cleavage, making it prone to breakage from impact. Turquoise has a low hardness and is easily scratched. Zircon is also noted as prone to breakage. These properties are crucial for determining appropriate jewelry settings and care routines.
Color and Appearance
- Turquoise is prized for its opaque, waxy luster and distinctive blue-green color. Its color is due to the presence of copper.
- Zircon is celebrated for its exceptional brilliance and fire, which can rival that of a diamond. The blue variety used for December is often a treated or natural light blue.
- Tanzanite is known for its vivid, saturated blue-violet hue, which can display a dramatic color change from blue to violet under different lighting conditions, a phenomenon known as pleochroism.
Symbolism and Metaphysical Beliefs
Across cultures, gemstones have been attributed with symbolic meanings and healing properties. While these beliefs are not scientifically verified, they remain an important part of the lore surrounding birthstones.
Turquoise has long been associated with protection, especially in Native American cultures where it was used as an amulet. It is also linked to wisdom, tranquility, and good fortune. Its connection to the sky and water reinforces themes of calm and clarity.
Zircon, with its diamond-like fire, has historically been associated with wisdom, honor, and purity. Some traditions link it to prosperity and spiritual grounding.
Tanzanite, as a modern gem, has developed contemporary symbolic meanings. It is often associated with transformation, intuition, and spiritual awareness. Its unique discovery story lends it an aura of rarity and special significance.
The sources also note that some modern sources attribute calming energies to topaz and citrine (November's stones), and similar peaceful qualities are sometimes extended to the blue hues of December's stones, though this is not explicitly stated for turquoise, tanzanite, or zircon in the provided materials.
Care and Cleaning
Due to their varying physical properties, each December birthstone requires specific care to maintain its beauty and integrity.
Turquoise: As a relatively soft and porous stone, turquoise should be protected from chemicals, perfumes, and prolonged exposure to sunlight, which can cause fading. Clean it with a soft, dry cloth. Avoid ultrasonic cleaners and steam, as they can damage the stone. Store it separately to prevent scratches.
Zircon: While generally durable, zircon can be brittle due to its crystal structure. It is best cleaned with warm, soapy water and a soft brush. Avoid sudden temperature changes and harsh chemicals. Store it in a soft cloth to prevent scratching by harder gems.
Tanzanite: Due to its perfect cleavage, tanzanite is highly sensitive to blows and pressure. It should never be subjected to ultrasonic cleaners or steam. Cleaning is best done with a soft brush, mild soap, and lukewarm water. Professional jewelers often recommend storing tanzanite jewelry in a padded box and removing it during physical activities.
General Advice for All: For any gemstone, it is advisable to have jewelry settings checked periodically by a professional to ensure stones are secure, especially for rings and bracelets that are subject to daily wear.
Conclusion
The December birthstones—Turquoise, Tanzanite, and Zircon—offer a remarkable spectrum of blue, from the opaque, earthy tones of turquoise to the brilliant fire of zircon and the vivid, velvety blue of tanzanite. Each stone carries a unique story: turquoise with its ancient cultural legacy, zircon with its diamond-like sparkle and global presence, and tanzanite with its recent, exclusive discovery in Tanzania. Their differing gemological properties, from hardness to cleavage, dictate specific care requirements, making informed choices essential for longevity. Whether chosen for its historical resonance, symbolic meaning, or simply its captivating color, a December birthstone provides a personal connection to the geology and history of our planet, making it a meaningful and enduring gem for those born in the final month of the year.