For those born in the final month of the year, December offers a unique privilege: a choice among three distinct and captivating birthstones. Tanzanite, turquoise, and zircon each bring their own history, geological story, and visual appeal to the table. While all three are celebrated for their beautiful blue hues—a color often associated with winter skies and tranquil waters—they are fundamentally different in composition, origin, and character. This article delves into the world of these three December birthstones, exploring their gemological properties, historical significance, sources, and care, providing a comprehensive guide for enthusiasts, collectors, and anyone looking to connect with their birth month’s gem.
History and Lore
The journey of these three stones to their modern birthstone status is a tale of both ancient tradition and relatively recent adoption.
Turquoise is the most ancient of the trio, with a history spanning thousands of years. In the Southwestern United States, Native American cultures were using turquoise over 2000 years ago to create beads, pendants, inlay work, and small sculptures. Its importance in this region’s culture is enduring. The stone’s appeal is not limited to the Americas; its name itself is derived from the French "pierre turquoise," meaning "Turkish stone," reflecting its historical trade route from Persia through Turkey. For centuries, turquoise has been prized for its vibrant color and has been associated with protection, health, and good fortune across various cultures.
Zircon has an equally long but more complex history. For centuries, it was often confused with diamond due to its high luster and fiery brilliance. In fact, zircon was once used as an affordable alternative to diamond in jewelry. Its journey to birthstone status is more modern. Zircon replaced lapis lazuli as a birthstone for December in 1952. This change was part of a broader update to birthstone lists to reflect contemporary availability and market trends.
Tanzanite is the newest member of the December birthstone family. Unlike the ancient turquoise and the centuries-old zircon, tanzanite was only discovered in the 20th century and was added to most birthstone lists in 1952, the same year as zircon. Its rapid ascent to gemological fame is a testament to its unique and captivating color. The stone’s addition to the modern birthstone chart represents the dynamic nature of gemology and the continual discovery of new and desirable gems.
Geological Formation and Sources
The origins of these three gems could not be more different, spanning distinct geological processes and global locations.
Turquoise is a hydrous phosphate mineral containing copper and aluminum. Its formation requires a specific geological environment where acidic, copper-rich water percolates through rocks containing aluminum and phosphorus. The resulting mineral is typically found in arid regions, which is why the Southwestern United States is a major source. The stone is often found in veins or nodules within host rock, and its color can range from blue to blue-green to yellowish green, depending on the mineral content of the surrounding rock.
Zircon is one of the oldest minerals on Earth, with crystals found in sediments dating back billions of years. It is a zirconium silicate (ZrSiO₄) that forms during the cooling of magma. While it is found in many places worldwide, including Australia, Sri Lanka, and Cambodia, the most significant sources for gem-quality zircon are often associated with specific geological settings like placer deposits, where heavier minerals accumulate.
Tanzanite is the most geographically restricted of the three. It is a variety of the mineral zoisite and is found almost exclusively in a single, small area in the Merelani Hills of northern Tanzania, near Mount Kilimanjaro. Its formation is linked to a unique geological event involving the heating of zoisite by magma, which then interacted with other minerals to create its signature blue-to-violet color. This extreme rarity is a key factor in its value and appeal.
Gemological Properties
Understanding the physical and chemical properties of these gems is essential for appreciation, identification, and care. The following table summarizes key data based on the provided sources.
| Gemstone | Chemical Composition | Hardness (Mohs Scale) | Typical Color | Common Treatments | Key Characteristics |
|---|---|---|---|---|---|
| Turquoise | Hydrous copper aluminum phosphate | 5-6 | Blue to blue-green to yellowish green | Stabilization (waxing, resin impregnation) | Opaque; often cut as cabochons; porous. |
| Zircon | Zirconium silicate (ZrSiO₄) | 6.5-7.5 | Natural: yellow, red, brown; Treated: blue, green, etc. | Heat treatment to produce blue, green, and other colors | High luster; "fire" similar to diamond; brittle. |
| Tanzanite | Calcium aluminum silicate hydroxide | 6.5-7 | Blue to bluish purple to bluish violet | Heat treatment (to produce the desirable blue color) | Trichroic (shows three colors); color shifts with viewing angle. |
Turquoise
Turquoise is an opaque mineral, meaning light does not pass through it. This quality dictates its typical use in jewelry. Because it is relatively soft (5-6 on the Mohs scale) and can be porous, it is most often cut into cabochons—a smooth, rounded shape that protects the stone and highlights its color. The most preferred color is a bright, even blue. To enhance durability and color, turquoise is frequently stabilized with wax or resin. This treatment is common and accepted in the trade, as it protects the stone from damage and discoloration.
Zircon
Zircon is known for its exceptional brilliance and fire, which can rival that of a diamond. Its hardness (6.5-7.5) makes it durable enough for most jewelry, though it can be brittle and prone to chipping if not handled with care. Natural zircon is most commonly found in yellow, red, or brown hues. However, the vast majority of blue zircon on the market (estimated at about 80%) is the result of heat treatment applied to brownish stones. This process is permanent and stable, creating the vibrant blue color that is now the most popular for this gem. Other colors like green can also be achieved through treatment.
Tanzanite
Tanzanite’s most famous property is its trichroism—the ability to show three different colors when viewed from different crystallographic directions: blue, violet, and burgundy. This dynamic quality makes its color appear to shift depending on the angle of view. The desirable blue-to-violet color we associate with tanzanite is almost always the result of heat treatment. Natural, untreated zoisite is typically brownish, and heating it to around 600 degrees Celsius removes the brown tones, revealing the stunning blue. With a hardness of 6.5 to 7, it is suitable for jewelry but requires care to avoid sharp blows.
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, these stones are imbued with rich symbolism and metaphysical meanings.
Turquoise is widely regarded as a talisman of protection, healing, and wisdom. In many cultures, it is believed to ward off negative energy and bring good fortune. Its association with the sky and water links it to tranquility and peace. For those born in December, it is thought to offer a sense of calm and spiritual grounding.
Zircon has historically been associated with prosperity and honor. Its fiery brilliance led to beliefs that it could stimulate creativity and inspire wisdom. Some traditions held that zircon could promote sound sleep and ward off nightmares. As a December birthstone, it is considered a stone of purity and clarity.
Tanzanite, being a modern discovery, lacks the ancient lore of the other two, but it has quickly accumulated modern metaphysical associations. It is often linked to transformation and spiritual awakening. Its unique color, born from intense heat, is seen as a symbol of rising above challenges. For December births, tanzanite is believed to foster calmness, enhance intuition, and promote a sense of purpose and understanding.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of these birthstones, and their requirements differ based on their properties.
Turquoise requires gentle handling. Due to its porosity and moderate hardness, it should not be exposed to harsh chemicals, cosmetics, or prolonged sunlight, which can cause discoloration. Cleaning is best done with a soft, dry cloth. If needed, a mild soap and lukewarm water solution can be used, but it must be dried thoroughly immediately. Avoid ultrasonic and steam cleaners.
Zircon, while harder, is brittle. It is susceptible to chipping and abrasion, especially in settings where it might be hit. It is generally safe to clean with warm, soapy water and a soft brush. However, due to the potential for thermal shock, it is advisable to avoid sudden temperature changes and to be cautious with ultrasonic cleaners, especially for stones that may have undergone fracture filling (though this is less common for gem-quality zircon).
Tanzanite has moderate hardness and good toughness but can be scratched by harder materials. It is best cleaned with warm, soapy water and a soft brush. Avoid ultrasonic cleaners and steam cleaning, as the heat and vibrations can cause damage. Given its trichroic nature and value, professional cleaning and inspection are recommended for jewelry settings.
Conclusion
The three December birthstones—tanzanite, turquoise, and zircon—offer a remarkable diversity of choice, each with a distinct story. Turquoise provides a link to ancient history and earthy, protective qualities. Zircon offers a brilliant, diamond-like fire with a legacy of being mistaken for the king of gems. Tanzanite, the newest of the trio, captivates with its unique color shift and rarity. Together, they represent the full spectrum of December’s character: from the ancient wisdom of the earth to the fiery brilliance of the cosmos and the transformative power of modern discovery. Whether chosen for their historical significance, geological wonder, or metaphysical properties, these three stones allow those born in December to carry a piece of the world’s diverse beauty with them.