December is unique in the gemological calendar, distinguished by having the most widely recognized birthstones of any month. This abundance offers a remarkable spectrum of blue hues, from the icy clarity of topaz to the earthy, matrix-veined beauty of turquoise. The four primary December birthstones—Blue Topaz, Zircon, Tanzanite, and Turquoise—each possess distinct geological origins, historical narratives, and gemological properties. While all share the winter’s cool color palette, their individual characteristics provide a diverse range of options for jewelry enthusiasts, collectors, and those born in the final month of the year. This article delves into the history, formation, properties, and care of these four celebrated gemstones, providing a definitive guide to December’s azure treasures.
The Historical Pathway to a Multi-Gemstone Month
The modern list of birthstones is not an ancient, immutable tradition but a standardized system that evolved over time. The standardization began in 1912 with the National Association of Jewelers, which sought to combine historical customs with gemstones practical for the commercial jewelry market. This list was later updated by the Jewelry Industry Council of America in 1952, which added Zircon to December’s offerings. The most recent addition was Tanzanite in 2002, reflecting the gemstone’s rising prominence and commercial appeal.
The reason for December’s four birthstones is not definitively documented in the provided materials, but one prevailing theory suggests it was to offer a wider array of colors and price points. Unlike months with a single birthstone, December’s multiple options allow for greater personal preference, style, and budget. This evolution underscores how birthstone lists can adapt to new discoveries and market trends, ensuring they remain relevant to contemporary buyers.
Blue Topaz: The Modern State Gem of Texas
Blue Topaz stands out as the most durable and commercially significant of the December birthstones. It is important to distinguish natural blue topaz, which is exceptionally rare, from the vast majority of blue topaz on the market, which is created through the heat treatment of colorless topaz. This process transforms colorless crystals into the desirable sky-blue to deep London Blue shades associated with December.
Geological Formation and Sources
Topaz is a silicate mineral, and its blue variety is sourced from multiple locations worldwide. Notably, Blue Topaz is mined in Sri Lanka, Brazil, Mexico, Nigeria, and the United States. In the U.S., it holds particular significance as the official state gem of Texas, with notable deposits also found in Utah and California. For rockhounds and gemstone enthusiasts, these U.S. locations offer opportunities for field collection, though proper preparation and research are essential.
Gemological Properties
Blue Topaz is the hardest of the four December birthstones, rating an 8 on the Mohs hardness scale. This makes it exceptionally suitable for daily wear, especially in rings and bracelets that are prone to knocks. Its chemical composition is a complex aluminum silicate containing fluorine and hydroxyl ions. The gem is typically transparent with a vitreous luster, and its color can range from a pale, icy blue to a saturated, deep blue.
Symbolism and Lore
Historically, the word "topaz" is believed to derive from the Sanskrit word "tapas," meaning fire. Ancient associations linked topaz to strength and protection. In its modern blue form, it has come to symbolize calmness, love, and clarity, making it a popular choice for romantic gifts and jewelry intended to convey fidelity and serenity.
Care and Cleaning
Due to its high hardness, Blue Topaz is relatively easy to care for. It can be cleaned with warm, soapy water and a soft brush. However, it is sensitive to sharp impacts, which can cause chipping or fracture, so it should be stored separately from other jewelry to avoid abrasion.
Zircon: The Traditional Sparkler with a Rainbow of Colors
Zircon is one of the oldest minerals on Earth, and its blue variety is the traditional December birthstone. It is crucial to distinguish natural zircon from the synthetic cubic zirconia (CZ), a common diamond simulant. Natural zircon is a distinct mineral with significant historical value and exceptional optical properties.
Geological Formation and Sources
Zircon forms in igneous and metamorphic rocks and is found in various locations worldwide. The primary sources for gem-quality zircon include Sri Lanka, Cambodia, and Australia. It is a common mineral in many rock types but finding large, clean crystals suitable for faceting is less common.
Gemological Properties
Zircon has a Mohs hardness of 6.5 to 7.5, making it moderately durable but somewhat brittle, particularly at its edges. This brittleness means it is best suited for earrings, pendants, and protected rings rather than bracelets or rings exposed to daily wear. Zircon is renowned for its high refractive index and strong dispersion, which gives it a brilliant sparkle and "fire" that can rival diamond. While it occurs in a range of colors (including brown, green, and yellow), the blue variety is most associated with December. Like topaz, much of the blue zircon on the market is heat-treated from brown zircon crystals.
Symbolism and Lore
Zircon is associated with clarity, wisdom, and a sense of balance. Historically, it has been valued for its protective qualities and was believed to promote honor and purity in the wearer.
Care and Cleaning
Zircon requires careful handling. It should be protected from sharp blows and cleaned using mild methods. Avoid steam and ultrasonic cleaners, as these can cause damage. Warm, soapy water and a soft cloth are recommended for maintenance.
Tanzanite: The Rare and Valuable Violet-Blue Treasure
Tanzanite is the newest addition to the December birthstone family, added in 2002. It is the rarest and often the most valuable of the four, prized for its vivid, pleochroic color that shifts between violet and blue depending on the viewing angle.
Geological Formation and Sources
Tanzanite’s rarity is directly tied to its exclusive origin. It is mined in only one place on Earth: a small, four-square-kilometer area in the Merelani Hills of Northern Tanzania. This geographic limitation makes it hundreds of times rarer than diamond. The gem is a variety of the mineral zoisite and is formed through a complex geological process involving heat and pressure.
Gemological Properties
Tanzanite has a Mohs hardness of 6 to 7, placing it in the moderate durability range. It is prone to chipping and should be handled with care, making it best suited for occasional-wear jewelry like earrings, pendants, and protected rings. Its most defining characteristic is its color: a rich, saturated violet-blue. Most tanzanite on the market is heat-treated to achieve this stable and desirable hue from its naturally brownish state.
Symbolism and Metaphysical Beliefs
Tanzanite is often linked to transformation and new beginnings. Its discovery in the 1960s and rapid rise to prominence give it a modern, dynamic symbolism compared to the ancient lore of turquoise and zircon.
Care and Cleaning
Tanzanite requires gentle care. It is sensitive to chemicals and heat. Cleaning should be done only with warm, soapy water and a soft brush. Avoid ultrasonic cleaners and steam, which can cause irreparable damage. Due to its cleavage, it is vulnerable to sharp knocks.
Turquoise: The Ancient, Opaque Protector
Turquoise is the primary and most historically significant December birthstone. Unlike the transparent gems above, turquoise is an opaque phosphate mineral, valued for its unique sky-blue to greenish-blue color, often veined with a brown or black matrix (the remnants of the host rock).
Geological Formation and Sources
Turquoise forms in arid regions where acidic, copper-rich water percolates through aluminum and phosphorus-bearing rocks. It is mined worldwide, with major sources in Iran (historically the finest), the United States (particularly Nevada, Arizona, and New Mexico), Tibet, and India. Each region produces turquoise with distinct color and matrix patterns.
Gemological Properties
Turquoise has a Mohs hardness of 5 to 6, making it the softest and most delicate of the December birthstones. It is porous and can be sensitive to chemicals, moisture, and skin oils. To enhance durability and color consistency, much of the commercial turquoise is stabilized—treated with resins or waxes to fill its pores. Natural, untreated turquoise is highly prized but requires more careful handling.
Symbolism and Lore
Turquoise carries profound cultural and historical significance. It was cherished by the pharaohs of ancient Egypt and carved by Chinese artisans over 3,000 years ago. Across cultures, it has been a talisman for protection, health, and good fortune. From the 13th century, it was believed to protect the wearer from falls, particularly from horses, and would break to signal impending danger. Hindu mystics associated it with wealth, believing that seeing a turquoise after the new moon ensured fortune. For many Native American tribes, particularly the Apache, it holds deep spiritual meaning, with legends linking it to finding a rainbow’s end.
Care and Cleaning
Due to its softness and porosity, turquoise requires the most careful maintenance. It should be cleaned only with a soft, dry cloth. Avoid all chemicals, including soapy water, as they can damage the stone’s surface or strip stabilizers. It should be stored away from heat and direct sunlight to prevent fading or cracking.
Comparative Analysis and Practical Considerations
Choosing among the four December birthstones involves balancing aesthetics, durability, and budget. The following table summarizes key properties for comparison:
| Property | Tanzanite | Turquoise | Zircon | Blue Topaz |
|---|---|---|---|---|
| Natural Color | Blue to violet | Sky blue to greenish | Blue (often heat-treated) | Pale blue to dark blue (often heat-treated) |
| Common Treatments | Heat treatment | Stabilization (resin/wax) | Heat treatment | Heat treatment |
| Mohs Hardness | 6 to 7 | 5 to 6 | 6.5 to 7.5 | 8 |
| Best For Jewelry | Occasional rings, earrings, pendants | Earrings, pendants, beads | Earrings, pendants, protected rings | Daily wear rings, all jewelry |
| Key Sensitivity | Prone to chipping | Sensitive to chemicals & moisture | Brittle at edges | Sensitive to sharp impacts |
| Geographic Origin | Tanzania only | Worldwide (Iran, USA, Tibet, etc.) | Sri Lanka, Cambodia, Australia | Worldwide (USA, Brazil, Sri Lanka, etc.) |
| Care Needs | Gentle cleaning only | Very gentle, avoid all chemicals | Avoid steam & ultrasonic | Mild care, avoid sharp hits |
For daily-wear jewelry like engagement rings, Blue Topaz is often recommended due to its superior hardness. Turquoise and Tanzanite are better suited for items with less exposure to impact, such as pendants or earrings. Zircon offers a brilliant sparkle for protected settings. In terms of value, Tanzanite is typically the most expensive due to its rarity, while Blue Topaz and Zircon often provide strong visual impact at a more accessible mid-range price point.
Conclusion
December’s birthstones offer a remarkable diversity within a shared color family. From the ancient, protective lore of Turquoise and the brilliant fire of Zircon to the modern rarity of Tanzanite and the durable elegance of Blue Topaz, each gemstone tells a unique story. Their collective history—from ancient civilizations to modern standardization—reflects the evolving relationship between humanity and the mineral world. Understanding their distinct origins, properties, and care requirements allows enthusiasts to make informed choices, whether selecting a piece of jewelry for daily wear or a special heirloom. Together, these four stones capture the serene and vibrant essence of December, providing a lifetime of beauty and meaning.