If you were born in December, you are gifted with a rare distinction in the world of gemology: the month boasts the most birthstone options of any calendar period. This abundance is reflected in a spectrum of blue hues, each stone carrying its own unique geological story, historical legacy, and symbolic meaning. The four modern birthstones for December—turquoise, blue topaz, tanzanite, and blue zircon—offer a diverse palette from the soft, sky-like tones of turquoise to the vibrant violet-blue of tanzanite and the brilliant, icy blue of topaz. This article delves into the rich tapestry of these gems, exploring their geological origins, gemological properties, historical significance, and the practical considerations for their care and selection.
The evolution of the December birthstone list is a testament to the dynamic nature of gemstone commerce and tradition. In 1912, the National Association of Jewelers standardized the unofficial American birthstones, a list that has been updated over time to reflect new discoveries and market trends. The addition of zircon in 1952 and tanzanite in 2002 expanded the options for December-born individuals, a move some believe was intended to provide more affordable and accessible choices. The official list now includes blue zircon, blue topaz, tanzanite, and turquoise, with traditional lists often featuring turquoise and lapis lazuli. This variety allows for personal preference, budget considerations, and an appreciation for the distinct characteristics each gem possesses.
Historical Lore and Cultural Significance
The historical narrative of each December birthstone is deep and varied, spanning millennia and continents. Turquoise, perhaps the most ancient of the group, has been cherished for thousands of years. Its use is documented in the funerary mask of King Tut, who ruled Egypt over 3,000 years ago, and Chinese artisans were carving it more than three millennia ago. Across cultures, turquoise has been imbued with profound protective and beneficial powers. In European tradition, a turquoise ring symbolized "forget me not," while in Tibet, it is considered a national treasure believed to grant health, good fortune, and protection from evil. Native American tribes held the stone in high regard; the Apache believed it could be found by following a rainbow to its end and that attaching it to a bow or firearm improved one’s aim. The Pueblo attributed the gem's color to the sky, and the Hopi thought it was produced by lizards scurrying over the earth. For centuries, it was also believed to protect the wearer from falls and to break into several pieces at the approach of disaster, a property that made it a popular amulet for travelers and horsemen.
Zircon's history is equally colorful, though its origins are shrouded in linguistic debate. The name may derive from the Arabic zarkun (cinnabar) or the Persian zargun (gold colored), a fitting description given the stone's broad color palette, which includes red, orange, yellow, brown, green, and blue. Colorless zircon, known for its exceptional brilliance and flashes of multicolored light called "fire," has been confused with diamond for centuries. During the Middle Ages, it was believed to induce deep sleep and ward off evil spirits. In Hindu tradition, zircon is one of the nine gems in the navaratna, and when worn together, these gems are said to protect the wearer and bring wealth, wisdom, and good health. Victorians were particularly fond of blue zircon, a preference that has persisted into the modern era.
The history of blue topaz is less defined, with its exact origins unknown, though it has been found throughout history. Its journey to becoming a modern birthstone is tied to the standardization of the 1912 list and subsequent updates. In contrast, tanzanite’s history is remarkably modern. Discovered in 1967 in Tanzania, it was introduced to the world by the jewelry company Tiffany & Co. in 1968. Recognizing its international appeal, Tiffany launched a major advertising campaign that transformed tanzanite into an instant sensation. Its vivid colors, high clarity, and potential for large cut stones captivated the market, leading to its official addition to the December birthstone list in 2002. Today, it is also recognized as the gem for the 24th wedding anniversary.
Geological Formation and Global Sources
The geological origins of these four gems are as diverse as their histories. Turquoise is a semi-translucent to opaque mineral that forms in arid regions where acidic water percolates through rocks containing aluminum and copper. This process creates nodules or veins, often accompanied by remnants of the host rock, known as matrix. Turquoise has been mined for over a millennium in the Nishapur district of Iran, a source renowned for its high-quality material. Other significant sources include the United States (particularly the Southwest), China, and Egypt.
Blue topaz, a silicate mineral, is found in several locations worldwide. Current mining sources include Sri Lanka, Brazil, Mexico, Nigeria, and the United States. Its durability and range of blue hues have made it a popular choice for jewelry, and it holds the distinction of being the official state gem of Texas.
Tanzanite is the rarest of the December birthstones, a fact directly linked to its unique and extremely limited geographic source. It is mined exclusively in the Merelani Hills of northern Tanzania, an area covering just a few square kilometers at the base of Mount Kilimanjaro. The mines, which can extend over 100 meters deep, are the only commercial source of this gem on Earth, which contributes significantly to its value and rarity. Tanzanite begins its life as brownish zoisite, which is heat-treated to achieve its characteristic blue to violet hues. This treatment is permanent and is considered a standard industry practice.
Zircon is a common mineral found in many types of rock, but gem-quality crystals are less frequent. Major sources for gem zircon include Australia, Thailand, Cambodia, and the United States. The blue variety, popular for December, often derives its color from heat treatment, which can transform brownish zircon into a vibrant blue.
Gemological Properties: A Scientific Profile
Understanding the physical and chemical properties of these gems is essential for both appreciation and care. The following table summarizes key gemological data for the December birthstones, based on the provided sources.
| Gemstone | Chemical Composition | Mohs Hardness | Typical Appearance | Key Durability Notes |
|---|---|---|---|---|
| Turquoise | Hydrated copper aluminum phosphate | ~5-6 (approximated from context) | Semi-translucent to opaque, blue to green with matrix veins | Softer stone; susceptible to scratching and chemical damage. |
| Blue Topaz | Aluminum silicate fluoride hydroxide | 8 | Transparent, brilliant icy blue | Hardest December birthstone; excellent for daily wear. |
| Tanzanite | Calcium aluminum hydroxyl silicate (Zoisite) | 6-7 | Transparent, vivid violet-blue to blue | Resistant to heat, light, and common chemicals; abrades easily; may crack with sudden temperature changes. |
| Blue Zircon | Zirconium silicate | 7.5 | Transparent, brilliant with high fire | Durable but can be brittle; heat-treated for color. |
Turquoise is a relatively soft stone, with a hardness typically between 5 and 6 on the Mohs scale. Its semi-translucent to opaque nature and characteristic matrix veins are defining features. It is sensitive to pressure, chemicals, and prolonged exposure to heat or light, which can cause discoloration or damage.
Blue Topaz stands out for its exceptional hardness of 8 on the Mohs scale, making it the most durable of the December birthstones for everyday wear. This resilience, combined with its brilliant blue color, makes it an excellent choice for rings and other pieces that may encounter daily activity.
Tanzanite has a hardness of 6 to 7, making it somewhat softer than topaz or zircon. While it is resistant to the effects of normal heat, light, and common chemicals, it can abrade easily and may crack if exposed to very high temperatures or sudden temperature changes. It is not recommended for daily wear in rings unless set in a protective mounting. The color of tanzanite is almost always the result of heat treatment, a permanent process that enhances the brownish zoisite into its prized blue-violet hues.
Blue Zircon possesses a hardness of 7.5, making it quite durable for jewelry. However, it can be brittle due to its crystal structure. Like tanzanite, the vibrant blue color of many zircons is achieved through heat treatment. Historically, colorless zircon has been used as a diamond simulant due to its high refractive index and "fire" (dispersion), which can rival that of diamond.
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, each December birthstone carries a legacy of symbolism and metaphysical belief. Turquoise is universally regarded as a stone of protection, health, and good fortune. It is said to impart peace to the wearer and is associated with the 11th wedding anniversary. In Hindu mysticism, seeing turquoise after beholding the new moon was believed to ensure fantastic wealth.
Blue Topaz is associated with wisdom and calmness. Its clear, icy blue color is often linked to clarity of thought and communication. While not as steeped in ancient lore as turquoise, its modern symbolism emphasizes tranquility and mental focus.
Tanzanite, as a modern discovery, has quickly accumulated its own set of meanings. Its rarity and unique color are associated with individuality, transformation, and vision. As the gem for the 24th wedding anniversary, it symbolizes a deep, enduring, and unique bond.
Zircon has been linked to a variety of powers throughout history. It was believed to promote sleep, ward off evil, and bring prosperity. As one of the nine gems in the Hindu navaratna, it is considered a stone of wisdom, wealth, and good health when part of a set.
Care and Cleaning for Longevity
Proper care is crucial to maintaining the beauty and integrity of any gemstone. The varying hardness and chemical stability of the December birthstones necessitate different maintenance approaches.
Turquoise, being the softest of the group, requires gentle handling. It should be cleaned only with warm, soapy water and a soft brush. It is highly susceptible to chemicals, including those in perfumes, lotions, and cosmetics, which can damage its surface and cause discoloration. It should be stored separately to avoid scratches from harder gems.
Blue Topaz, with its hardness of 8, is relatively easy to care for. It can be cleaned using warm, soapy water and a soft brush. Ultrasonic and steam cleaners are generally safe for topaz, but it is always prudent to confirm with a professional if the stone has been treated or is set in delicate jewelry.
Tanzanite demands careful handling. The recommended cleaning method is warm, soapy water. Ultrasonic and steam cleaners should never be used for tanzanite, as vibrations and heat can cause internal fractures or exacerbate existing ones. Due to its susceptibility to abrasion and thermal shock, tanzanite jewelry, especially rings, should be worn with consideration for protective settings and removed during strenuous activities.
Blue Zircon, while hard, can be brittle. Cleaning with warm, soapy water and a soft brush is safe. Care should be taken with ultrasonic cleaners, as the vibrations might cause damage if the stone has inclusions or fractures. Avoiding sudden temperature changes is also advisable to prevent thermal stress.
For all gemstones, removing jewelry before engaging in physical work, swimming, or applying cosmetics can significantly extend their lifespan and preserve their luster.
Conclusion
The December birthstones present a remarkable collection of gems, each with a distinct identity. From the ancient, protective talisman of turquoise to the brilliant, diamond-like fire of zircon, the icy durability of topaz, and the rare, modern allure of tanzanite, there is a stone to suit every preference and purpose. Their shared blue coloration connects them to the winter season, while their diverse origins, properties, and histories offer a rich field for exploration. Whether chosen for a birthday, an anniversary, or simply for their beauty, these four gems provide a lasting connection to the earth's geological wonders and humanity's enduring fascination with color and symbolism.