December is uniquely blessed in the world of birthstones, holding a quartet of gemstones that share a common thread: a captivating blue hue. While most months are assigned a single gemstone, December offers a choice of four—blue zircon, blue topaz, tanzanite, and turquoise. This abundance provides a remarkable range of options for those born in the final month of the year, from the ancient allure of turquoise to the modern brilliance of tanzanite. Each stone carries its own distinct history, geological origin, and set of gemological properties, yet all are united by their wintry, blue coloration that mirrors the season's icy skies and deep twilight. This guide delves into the characteristics, lore, and practical considerations for each of these four December birthstones, offering a comprehensive resource for gemstone enthusiasts, jewelry buyers, and students of gemology.
The Historical Evolution of December's Birthstones
The concept of birthstones is ancient, with roots tracing back to civilizations such as Egypt, Greece, and Rome, where gemstones were believed to possess mystical and healing properties. However, the standardized list of birthstones as we know it today is a more modern creation. In 1912, the National Association of Jewelers in the United States established an official list, aiming to combine historical customs with gemstones that were practical for jewelry companies to sell. This list has been updated over time to reflect new discoveries and market trends.
For December, the journey to its current four-stone lineup was a gradual process. The 1912 standardization did not initially include blue zircon. It was added in 1952 by the Jewelry Industry Council of America. Tanzanite, a much more recent discovery, was officially added to the list in 2002, solidifying the four-stone tradition. The reason for December having the most birthstone options is not definitively known, but some sources suggest it was to provide more affordable choices for consumers. The evolution of birthstones demonstrates how new gemstone discoveries and commercial offerings can shape long-standing traditions.
Blue Zircon: The Traditional Sparkler
Blue zircon is one of the traditional birthstones for December, known for its exceptional brilliance and fire. It is a silicate mineral with a chemical formula of ZrSiO₄. Zircon is one of the oldest minerals on Earth, with crystals found in ancient rocks that are over 4 billion years old. While zircon occurs in a variety of colors, the blue variety is particularly prized for December.
The name "zircon" may derive from the Persian word "zargun," meaning gold-colored, though blue zircon is, of course, not gold-colored. Its most notable gemological property is its high refractive index, which gives it a brilliant sparkle that can rival that of a diamond. On the Mohs scale of hardness, zircon has a rating of 6.5 to 7.5. While this makes it reasonably durable, it is important to note that zircon can be brittle and susceptible to chipping due to its cleavage. Therefore, while it can be worn in jewelry, it requires careful handling and is not ideally suited for rings that might experience frequent impact.
Most blue zircon on the market is heat-treated to achieve its desirable blue color. Natural blue zircon is rare. The gemstone's color ranges from a light, sky blue to a deeper, more saturated hue. Its brilliance and clarity make it a popular choice for earrings and pendants, where it is less likely to suffer damage than in a ring setting.
Blue Topaz: The Modern Durable Choice
Blue topaz is a modern addition to the December birthstone family and has become one of the most popular choices due to its affordability, durability, and striking color. As a silicate mineral composed of aluminum and fluorine, blue topaz has a glass-like luster and exhibits deep cleavage, which can make it somewhat delicate despite its hardness.
On the Mohs scale, blue topaz ranks at an 8, making it the hardest of the four December birthstones and an excellent choice for everyday wear. Its color range is vast, from pale, almost translucent hues to deep, inky blues. The most well-known varieties include: * London Blue Topaz: A deep, inky blue that is highly prized by collectors. * Swiss Blue Topaz: A vibrant, medium-light blue that is immediately eye-catching. * Sky Blue Topaz: A light aqua color reminiscent of clear blue skies.
It is important to note that most commercially available blue topaz is produced by irradiating naturally colorless topaz. This process is stable and safe, resulting in a permanent blue color. The name "topaz" is believed to derive from the Sanskrit word for "fire," though its origin is also linked to the Greek "Topazios," an ancient name for an island in the Red Sea. Ironically, the stones found on that island were later identified as peridot, not topaz, but the name persisted.
Blue topaz is the official state gem of Texas and is mined in several countries, including Sri Lanka, Brazil, Mexico, Nigeria, and the United States. Its combination of hardness, brilliant color, and relative affordability makes it a staple in modern jewelry, from minimalist rings to elaborate statement necklaces.
Tanzanite: The Rare and Valuable Newcomer
Tanzanite is the most valuable and rarest of the four December birthstones. Discovered in the 20th century, it was added to the official birthstone list in 2002. Its rarity stems from a unique geological circumstance: it is found in only one location on Earth—a small mining area in the Merelani Hills of northern Tanzania. This limited source makes it approximately a thousand times rarer than diamond.
Tanzanite is a variety of the mineral zoisite and is prized for its mesmerizing blue-violet color, which is pleochroic—showing different colors (blue and violet) from different crystal angles. This phenomenon gives the stone a captivating depth and complexity. The gemstone's color is typically the result of heat treatment, which removes brownish hues and enhances the blue-violet tones. Natural, untreated tanzanite of gem quality is exceptionally rare.
As a relatively recent addition to the birthstone family, tanzanite lacks the ancient lore of turquoise or zircon. However, its modern symbolism is often linked to transformation, clarity, and new beginnings, reflecting its own story of being a "gemstone of a generation." Its value and rarity make it a sought-after centerpiece for fine jewelry, particularly in rings, earrings, and pendants. Due to its relative softness (Mohs hardness of 6.5-7) and cleavage, it requires careful wear and professional cleaning.
Turquoise: The Ancient Talisman
Turquoise is the most ancient of the December birthstones, with a history of use and reverence spanning thousands of years. Unlike the other three gemstones, turquoise is not a single mineral but a hydrated phosphate of copper and aluminum. Its distinctive blue-to-green color comes from copper, while the presence of iron can shift the hue toward green. Turquoise is often found in matrix rock, where the host rock becomes part of the gem, creating unique, web-like patterns.
This gemstone has been cherished by cultures worldwide, from ancient Egypt and Persia to the Native American tribes of the southwestern United States. It has long been believed to possess protective and healing properties. Sources describe it as a "steadying force," valued for protection, grounding, and a sense of calm. Its name is derived from the French "pierre turquoise," meaning "Turkish stone," as it was brought to Europe from Turkey.
Turquoise is relatively soft, with a Mohs hardness of 5 to 6, and has a porous structure. This makes it susceptible to damage from chemicals, heat, and even body oils, which can cause discoloration over time. It is often stabilized or treated to enhance its durability and color. Despite its delicacy, its rich cultural history and unique, earthy beauty ensure its enduring popularity in both traditional and contemporary jewelry.
Comparative Gemological Properties
Understanding the physical characteristics of these gemstones is crucial for both appreciation and care. The following table summarizes key properties based on the provided sources.
| Gemstone | Mineral Family | Chemical Composition | Mohs Hardness | Key Characteristics | Primary Sources |
|---|---|---|---|---|---|
| Blue Zircon | Silicate | ZrSiO₄ | 6.5 - 7.5 | High brilliance and fire; brittle with cleavage. | Various global sources. |
| Blue Topaz | Silicate | Al₂(F,OH)₂SiO₄ | 8.0 | Hardest of the four; deep cleavage; most color is irradiated. | Sri Lanka, Brazil, Mexico, Nigeria, USA. |
| Tanzanite | Silicate (Zoisite) | Ca₂Al₃(SiO₄)₃(OH) | 6.5 - 7.0 | Pleochroic (blue/violet); rare; typically heat-treated. | Merelani Hills, Tanzania (exclusively). |
| Turquoise | Phosphate | CuAl₆(PO₄)₄(OH)₈·4H₂O | 5.0 - 6.0 | Porous; often contains matrix; color from copper. | USA (Arizona, New Mexico), Iran, China. |
Symbolism and Metaphysical Beliefs
Across cultures and centuries, gemstones have been imbued with symbolic meaning. While these beliefs are not scientifically verified, they form a significant part of the gemstones' cultural heritage.
- Turquoise is universally associated with protection, wisdom, and good fortune. It is often seen as a grounding stone that promotes inner calm and stability.
- Tanzanite, as a modern discovery, has more contemporary associations. It is frequently linked to transformation, spiritual awakening, and the ability to see a path forward with clarity.
- Blue Zircon is historically believed to promote prosperity and honor. Its brilliant sparkle is said to attract wealth and success.
- Blue Topaz is often associated with calmness, peace, loyalty, and love. Its clear, cool blue is thought to soothe emotions and enhance communication.
These symbolic attributes add a layer of personal significance to the gemstones, making them meaningful gifts beyond their physical beauty.
Care and Cleaning Considerations
Proper care is essential to maintain the beauty and longevity of any gemstone jewelry. The varying hardness and structural properties of the December birthstones require specific attention.
- Blue Topaz: Due to its hardness of 8, blue topaz is quite durable. However, its deep cleavage means it can be chipped by a sharp blow. It can be cleaned with warm, soapy water and a soft brush. Avoid ultrasonic cleaners and sudden temperature changes.
- Blue Zircon: With a hardness of 6.5-7.5, it is moderately durable but brittle. It should be protected from knocks and stored separately to avoid scratching. Clean gently with warm, soapy water and a soft cloth. Avoid steam and ultrasonic cleaners.
- Tanzanite: Ranking 6.5-7 on the Mohs scale and possessing good cleavage, tanzanite requires careful handling. It is best suited for earrings or pendants rather than rings. Clean with warm, soapy water and a soft brush. Avoid ultrasonic cleaners and harsh chemicals.
- Turquoise: As the softest and most porous of the group, turquoise demands the most care. It should never be exposed to chemicals, cosmetics, or even excessive skin oils, which can cause discoloration. Clean it with a soft, dry cloth. Avoid soaking in water or using any cleaning solutions. Store it away from direct sunlight and heat.
Conclusion
The four birthstones of December—blue zircon, blue topaz, tanzanite, and turquoise—offer an unparalleled diversity within a unified blue palette. From the ancient, protective talisman of turquoise to the rare, modern elegance of tanzanite, each gemstone provides a unique narrative. The durable and brilliant blue topaz and the fiery sparkle of blue zircon complete the quartet, ensuring that every December-born individual can find a gemstone that resonates with their personal style and story. This rich variety not only reflects the gemological diversity of our planet but also the evolving nature of tradition itself, where new discoveries can enhance and expand ancient customs. Understanding their individual histories, properties, and care requirements allows for a deeper appreciation of these beautiful symbols of the winter month.