The month of December is uniquely distinguished in the world of gemology by its association with three distinct and celebrated birthstones: Turquoise, Tanzanite, and Zircon. While each stone shares a captivating blue hue, they possess vastly different origins, chemical compositions, histories, and cultural significances. For those born in the final month of the year, this offers a rich palette of choices, allowing for personal selection based on aesthetic preference, budget, and the unique lore attached to each gem. This guide provides an in-depth exploration of these three remarkable stones, detailing their geological formation, gemological properties, historical journey, and the symbolic meanings that have been ascribed to them through millennia.
Turquoise: The Ancient Stone of Protection
Turquoise stands as the most traditional and ancient of the December birthstones, with a history of human admiration and use that spans over 6,000 years. Its name, derived from the French phrase "pierre tourques" or "Turkish stone," tells a story of its trade routes. The gem was mined in Persia and along the Sinai Peninsula and was transported to Europe through the gem markets of Constantinople, Turkey, hence its name.
History and Lore Across numerous cultures, Turquoise has been revered as a powerful amulet. Its relative softness and waxy texture made it easy to cut and carve, allowing ancient peoples to inscribe it with protective symbols and inscriptions. It was widely believed to possess the power to ward off danger and bring good fortune. A fascinating belief held that the stone could warn its wearer of impending illness or danger by changing its color, becoming pale. This characteristic cemented its role as a protective talisman.
In Tibet, Turquoise was considered a birthstone of fortune, health, and success, so valued that it was often used as a form of currency. For the ancient Incas and Mayas, it was a sacred offering to their gods. Among Native American tribes of the American Southwest, the gem was deeply associated with youth and strength. It was also prized by lovers and married couples as a gemstone to protect their relationships and was believed to preserve friendship if given as a gift. The Almanac notes that Hindu mystics believed seeing a turquoise after observing a New Moon would bring wealth, and dating back to the 13th century, it was thought to protect wearers from falling, leading to its use on horse bridles. A more somber belief held that the gem would break into multiple pieces when disaster was imminent.
Geological Formation and Sources Turquoise is an opaque mineral that forms when water containing copper and aluminum seeps through pre-existing rock, a process that can take millions of years. Its color spectrum ranges from sky blue to green, depending on the amount of copper (blue) and iron (green) present. Many stones exhibit dark veining or a "matrix," which is fragments of the host rock trapped within the gem.
Certain varieties are highly prized for their specific characteristics. Persian turquoise, historically sourced from Iran, is celebrated for its vivid, evenly saturated sky-blue color and its characteristically minimal to nonexistent matrix. Another famous variety is Sleeping Beauty Turquoise, known for its pure, robin's-egg blue color and exceptionally low matrix. This stone was mined exclusively from the Sleeping Beauty Mine in Arizona before its closure.
Gemological Properties Turquoise is a hydrous phosphate of copper and aluminum. It is semi-translucent to opaque and can appear waxy to the touch. While it is one of the older birthstones, its durability is moderate. It has a hardness of 5 to 6 on the Mohs scale, making it susceptible to scratching and chipping. Care should be taken to avoid exposure to chemicals, cosmetics, and even skin oils, which can cause discoloration. Cleaning should be done with a soft, dry cloth.
Tanzanite: The Rare Stone of Transformation
Tanzanite is a relative newcomer to the gemstone world, both in its geological formation and its recognition as a birthstone. This rare blue-violet gem is celebrated for its singular origin and captivating optical properties.
History and Lore Tanzanite was first discovered in the 1960s in the Mererani Hills of Northern Tanzania, making it one of the most unique gemstones in the world as it is found in only one location on Earth. Its rarity is often quantified as being 1,000 times rarer than diamond. Due to its discovery and popularization by Tiffany & Co., it does not have the ancient lore of Turquoise, but it has quickly developed its own symbolic meaning. It is often regarded as a "stone of transformation" due to its deep metaphysical properties. Modern sources suggest it is believed to enhance spiritual awareness, promote emotional healing, and help relieve stress. It is also known to encourage personal growth and mental clarity, making it a perfect choice for those seeking to evolve and overcome emotional or spiritual challenges.
Gemological Properties Tanzanite is a variety of the mineral zoisite. Its most remarkable characteristic is its strong pleochroism, which means it displays three distinct hues—blue, violet, and burgundy—depending on the angle at which it is viewed. Gem cutters must carefully orient the rough stone to showcase the desirable blue and violet tones. The gem is treated with heat to achieve its stable blue color; most natural zoisite is brownish, and heating removes the brownish-yellow tones.
Tanzanite has a hardness of 6.5 to 7 on the Mohs scale, making it suitable for jewelry but requiring some care to avoid sharp blows. It is also known to have poor toughness due to one direction of perfect cleavage, meaning it can split along a specific plane if struck with sufficient force.
Zircon: The Brilliant Stone of Virtue
Zircon is the third official December birthstone, known for its exceptional brilliance and fire. It is one of the oldest minerals on Earth, containing radioactive elements that allow geologists to date the formation of the Earth's crust.
History and Lore Zircon has a long and storied history. In the Middle Ages, it was believed to bring wisdom, honor, and prosperity. It was also thought to induce sleep and ward off evil spirits. The name "zircon" may derive from the Persian word "zargun," meaning "gold-colored," though its most famous color is a brilliant blue. Blue zircon, in particular, was a popular gem during the Victorian era in the United Kingdom, often used in jewelry.
Gemological Properties Zircon is a mineral composed of zirconium silicate. It should not be confused with the man-made cubic zirconia, which is a diamond simulant. Natural zircon is a distinct gem with its own set of properties. It has a high refractive index, which gives it exceptional brilliance and fire, often compared to that of a diamond. It also exhibits strong birefringence (double refraction).
Zircon is available in a variety of colors, including blue, yellow, green, red, and brown. The most popular color for jewelry is the vibrant blue, which is typically achieved through heat treatment of brown zircon. With a hardness of 6.5 to 7.5 on the Mohs scale, it is reasonably durable for most jewelry applications. However, it can be brittle, so care should be taken to avoid hard impacts.
Comparison of Properties
| Property | Turquoise | Tanzanite | Zircon |
|---|---|---|---|
| Mineral Family | Phosphate | Zoisite (Nesosilicate) | Zirconium Silicate (Nesosilicate) |
| Chemical Formula | Hydrous phosphate of copper & aluminum | Ca2Al3(SiO4)3(OH) | ZrSiO4 |
| Color(s) | Sky blue to green, often with brown/black matrix | Blue, violet, burgundy (pleochroic) | Blue, yellow, green, red, brown |
| Hardness (Mohs) | 5 - 6 | 6.5 - 7 | 6.5 - 7.5 |
| Crystal System | Triclinic | Orthorhombic | Tetragonal |
| Transparency | Opaque to semi-translucent | Transparent to translucent | Transparent to translucent |
| Key Characteristic | Matrix patterns, color variation | Strong pleochroism | High Brilliance & Fire (Refractive Index) |
Care and Cleaning
The care required for each of these gemstones varies significantly based on their physical properties.
Turquoise: As the softest of the three, Turquoise requires the most care. It is porous and can be damaged by chemicals, lotions, soaps, and even prolonged exposure to skin oils, which can cause it to discolor or become "greened." It should be cleaned only with a soft, dry cloth. Avoid ultrasonic cleaners and steam cleaners.
Tanzanite: Due to its perfect cleavage, Tanzanite is more susceptible to breaking from a sharp blow than Zircon. It is also softer than Zircon. It is best cleaned with warm, soapy water and a soft brush. Avoid ultrasonic cleaners and extreme temperature changes.
Zircon: While Zircon is relatively hard, it is brittle and can fracture from a hard impact. It is generally safe to clean with warm, soapy water and a soft brush. Ultrasonic cleaning is usually safe, but steam cleaning is not recommended due to potential inclusions and the possibility of thermal shock.
Conclusion
The birthstones of December—Turquoise, Tanzanite, and Zircon—offer a remarkable diversity within a shared color palette. Turquoise connects us to ancient civilizations and the enduring human desire for protection and good fortune. Tanzanite provides a modern marvel, a stone of transformation whose rarity and unique optical properties captivate the contemporary gem enthusiast. Zircon, the brilliant and ancient, offers a fire and sparkle that rivals the most prized of gems. Together, they provide a rich and varied selection for those born in December, allowing each individual to choose a stone that not only reflects their personal style but also resonates with a history and meaning all its own.