Introduction
December is unique in the world of birthstones, being one of the few months with multiple official gemstones. The vibrant blue and cool-toned stones associated with December—Turquoise, Tanzanite, Zircon, and Blue Topaz—reflect serenity and wisdom, making them a popular choice for those born during this festive time of year. These gemstones are not only admired for their beauty but also for the rich tapestry of history, geology, and symbolism they carry. From ancient talismans to modern red-carpet jewelry, December's birthstones offer a fascinating intersection of cultural heritage and gemological science.
This article explores the gemological properties, historical origins, and cultural significance of the primary December birthstones, with a particular focus on their connections to the zodiac signs of Sagittarius and Capricorn. We will delve into how these stones are formed, where they are mined, and the beliefs that have shaped their meanings over centuries, providing an in-depth guide for gemstone enthusiasts, jewelry buyers, and students of gemology.
History and Lore
The concept of birthstones dates back centuries, with early records tracing to the Breastplate of Aaron, described in the Book of Exodus. This sacred Jewish artifact, worn by the High Priest, featured twelve gemstones representing the twelve tribes of Israel. This ancient tradition laid the groundwork for the modern birthstone lists, which have evolved over time. The modern birthstone list for December is Blue Zircon as the traditional stone, with Blue Topaz, Tanzanite, and Turquoise as alternate representatives.
The association of specific gemstones with December is relatively modern. The American National Association of Jewelers (now Jewelers of America) established the official birthstone list in 1912, with later updates adding more stones. Turquoise, with its long history, was likely included due to its enduring popularity. Tanzanite was added in 2002 as a modern alternative, recognizing its recent discovery and rising prominence in the gem market. Blue Zircon and Blue Topaz were included to provide a range of blue options, as the color blue is the designated birthstone color for December.
Zodiac Associations
December spans two zodiac signs: Sagittarius (November 22 – December 21) and Capricorn (December 22 – January 19). Different gemstones are traditionally associated with each sign, offering those born in December a variety of choices.
Sagittarius (November 22 – December 21) Sagittarius is a fire sign, and its primary birthstone is Topaz, particularly blue topaz. Topaz is said to help Sagittarians channel their optimism, seek adventure, and provide protective energy during travels. Turquoise is also considered a secondary stone for Sagittarius, offering additional luck and protection. The planetary association for Sagittarius is Jupiter, and its element is fire.
Capricorn (December 22 – January 19) Capricorn is an earth sign, and its primary birthstone is Ruby. However, for the December portion of Capricorn, Zircon is a significant traditional stone. Zircon is believed to help Capricorns with grounding, discipline, and ambition, clearing mental blocks for better focus. Turquoise is also beneficial for Capricorn, promoting emotional balance and inner peace. The planetary associations for Capricorn are Saturn, and its element is earth.
Both signs benefit from the calming energy of blue stones like turquoise, tanzanite, and blue topaz, which promote emotional balance and inner peace, countering the potential winter blues associated with the season.
Geological Formation and Sources
The December birthstones originate from diverse geological environments across the globe. Their formation processes are as varied as their appearances.
Turquoise Turquoise is an opaque mineral, a phosphate of copper and aluminum. It forms when groundwater containing copper seeps into bedrock, often in arid regions. Over time, reactions with other minerals create the stunning blue and green hues. The dark lines and shapes seen in turquoise are derived from the surrounding rock, known as matrix. Major sources for turquoise include Iran (historically the most prized), the United States (particularly Arizona and New Mexico), Tibet, and India.
Tanzanite Tanzanite is a blue to violet variety of the mineral zoisite. It is found in only one location worldwide: the Merelani Hills of Tanzania, near the base of Mount Kilimanjaro. Its formation is geologically unique, requiring specific conditions of heat and pressure that occurred during the formation of the East African Rift. This limited geographic source makes tanzanite exceptionally rare.
Zircon Zircon is a zirconium silicate mineral. It is one of the oldest minerals on Earth, with crystals found in ancient rocks. Blue zircon, the variety most associated with December, is typically heat-treated to achieve its vibrant blue color from brown or yellowish natural zircon. Sources for zircon are widespread, including Cambodia, Sri Lanka, and Australia.
Topaz Topaz is a fluorine aluminum silicate mineral. While topaz occurs in a wide range of colors, the blue variety used in December birthstone jewelry is most often created through irradiation and heat treatment of colorless topaz. Natural blue topaz is extremely rare. Major sources for topaz include Brazil, Sri Lanka, and Russia.
Gemological Properties
Understanding the physical and chemical properties of these gemstones is crucial for identification, valuation, and care. The following table summarizes the key gemological characteristics of the December birthstones based on available data.
| Gemstone | Mineral Group | Chemical Composition | Mohs Hardness | Typical Colors | Key Properties |
|---|---|---|---|---|---|
| Turquoise | Phosphate | CuAl₆(PO₄)₄(OH)₈·4H₂O | 5 - 6 | Sky blue, greenish-blue | Opaque, often contains matrix (host rock). |
| Tanzanite | Zoisite | Ca₂Al₃(SiO₄)₃(OH) | 6.5 - 7 | Blue to violet | Pleochroic (shows different colors from different angles). |
| Zircon | Zircon | ZrSiO₄ | 7.5 | Blue (treated), white, yellow | High refractive index and dispersion ("fire"). |
| Topaz | Topaz | Al₂SiO₄(F,OH)₂ | 8 | Blue (treated), colorless, yellow | Can be created through treatment of colorless topaz. |
Turquoise is relatively soft, with a hardness of 5 to 6 on the Mohs scale, making it more susceptible to scratching and requiring careful handling. Its opacity is a defining characteristic.
Tanzanite has a hardness of 6.5 to 7, making it more durable than turquoise but still requiring care. Its most notable property is its strong trichroism, displaying blue, violet, and reddish tones depending on the viewing angle. Cutters orient the stone to show the most desirable blue-violet hue.
Zircon is a hard and durable gemstone, with a Mohs hardness of 7.5. It possesses a high refractive index and high dispersion, giving it exceptional brilliance and "fire" that can rival diamond. The blue variety is almost always the result of heat treatment, which is stable and accepted in the gem trade.
Topaz is one of the hardest silicate minerals, with a Mohs hardness of 8, making it very resistant to scratching. The blue color in most commercial topaz is not natural but is achieved through treatment, which is permanent and widely accepted.
Symbolism and Metaphysical Beliefs
The December birthstones are steeped in symbolism and metaphysical lore, which has contributed to their enduring appeal.
Turquoise is considered a sacred stone in many cultures. Historically, it has been a talisman for protection, friendship, and good fortune. Native American tribes, particularly in the Southwest United States, have revered turquoise for centuries, believing it connects the wearer to the sky and provides healing and strength. It is often called the "stone of the earth and sky."
Tanzanite, a relatively new gemstone, has quickly accumulated symbolic meaning. It is associated with transformation, intuition, and spiritual awakening. Its unique blue-violet color is linked to the throat and brow chakras, promoting clear communication and higher consciousness. Some modern sources suggest it embodies the new millennium's energy, though this is not widely accepted in formal gemology.
Zircon (particularly blue zircon) is believed to bring prosperity, honor, and wisdom. It is thought to enhance self-confidence and encourage a positive outlook. In medieval times, zircon was considered a protective stone against lightning and pestilence.
Topaz is traditionally associated with calm, peace, and diplomacy. Blue topaz, in particular, is linked to the throat chakra, aiding in clear and truthful communication. It is also believed to alleviate stress and promote relaxation.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of December birthstone jewelry. The varying hardness and properties of these stones dictate specific cleaning methods.
General Guidelines for All Stones: - Clean gently with lukewarm soapy water and a soft brush (e.g., a soft-bristled toothbrush). - Rinse thoroughly with clean water. - Pat dry with a soft, lint-free microfiber cloth. - Avoid harsh chemicals, ultrasonic cleaners, and steam cleaners for most stones, especially turquoise. - Store jewelry separately to prevent scratching, particularly since turquoise is softer than the others.
Specific Considerations: - Turquoise: Due to its porosity and lower hardness, it is especially sensitive to chemicals, cosmetics, and even body oils. It should be the last thing you put on and the first thing you take off. Avoid prolonged exposure to sunlight, which can fade the color. - Tanzanite: While harder than turquoise, it can be brittle. Avoid sudden temperature changes and impact. Ultrasonic cleaners are not recommended. - Zircon: Although hard, zircon can be brittle. Avoid knocking it against hard surfaces. It is generally safe to clean with a mild soap and soft brush. - Topaz: As the hardest of the group, it is more durable. However, avoid using harsh chemicals or abrasives. Ultrasonic cleaning is generally safe for untreated blue topaz.
Conclusion
The December birthstones—Turquoise, Tanzanite, Zircon, and Blue Topaz—offer a remarkable diversity in origin, appearance, and meaning. From the ancient, earthy charm of turquoise to the modern, vibrant allure of tanzanite, each stone carries a unique story. Their deep blue hues connect them to the winter season and provide a symbolic link to the zodiac signs of Sagittarius and Capricorn, offering traits of protection, wisdom, and emotional balance. Understanding their geological formation, gemological properties, and cultural significance enriches the appreciation of these gemstones, whether worn as a personal talisman or as a cherished piece of jewelry. Their enduring popularity is a testament to their beauty and the profound human connection to the mineral world.