December is uniquely endowed in the world of gemstones, offering a trio of captivating blue birthstones that mirror the cool, wintry skies of its season. While modern lists often expand this selection, the traditional and most widely recognized December birthstones are Turquoise, Tanzanite, and Blue Zircon, each with a distinct geological origin, historical narrative, and set of gemological characteristics. These stones have been cherished for millennia, transitioning from ancient amulets to contemporary fine jewelry, and their stories are deeply woven into the fabric of human culture and geological science. This article will explore the rich history and lore of each gemstone, delve into their geological formation and sources, detail their specific gemological properties, and discuss the symbolism and metaphysical beliefs that have sustained their popularity. Finally, it will provide practical guidance on the care and cleaning of these beautiful stones, ensuring their longevity for generations to come.
History and Lore
The concept of birthstones is ancient, with roots in the breastplate of the High Priest of Israel described in the Book of Exodus, which featured twelve gemstones representing the twelve tribes of Israel. This tradition evolved over centuries, with different cultures assigning specific stones to months. The modern list of birthstones was largely standardized in 1912 by the American National Association of Jewelers, though it has seen minor updates since. For December, the stones of Turquoise, Tanzanite, and Zircon each carry a legacy that predates this formalization.
Turquoise
Turquoise is arguably the oldest birthstone in the December collection, with a history spanning thousands of years. Its name is derived from the French pierre turquoise, meaning "Turkish stone," as it was brought to Europe from the mines of Persia (modern-day Iran) through Turkish trade routes. However, its use predates this trade by millennia. Ancient civilizations, including the Egyptians, Persians, Mesopotamians, and Native Americans of the Southwest, prized turquoise for its protective qualities and vibrant color. It was used in amulets, jewelry, and ceremonial objects. The Egyptians mined it as early as 3000 BCE, and it was famously set in the burial mask of King Tutankhamun. In Tibet, turquoise was so valued it was used as a currency and was considered a stone of fortune, health, and success. The ancient Incas and Mayas offered turquoise to their gods, while Native American tribes associated it with youth and strength. Historically, turquoise was believed to change color to warn its wearer of impending danger or illness, and it was thought to protect against falls and negative energy. It was also a favorite of lovers and married couples, believed to safeguard relationships and preserve friendship when gifted.
Tanzanite
In stark contrast to Turquoise's ancient lineage, Tanzanite is a remarkably modern addition to the birthstone family. This gemstone was discovered in the Merelani Hills of Northern Tanzania in 1967. Its discovery was relatively recent, and it was not widely known until the late 1960s and early 1970s, when it was marketed as a "gemstone of a generation." The stone’s unique blue-violet hue, which can appear sapphire blue from certain angles and violet from others, captivated the jewelry world. Its rapid rise to prominence was aided by a major jewelry retailer's promotional campaign in the early 1970s, which established it as a desirable and fashionable gemstone. While it lacks the millennia-old history of turquoise, its story is one of modern gemological discovery and successful marketing, quickly earning it a place as a traditional December birthstone. Its lore is often associated with transformation, clarity, and new beginnings, reflecting its relatively recent emergence into the gemstone market.
Zircon
Zircon is one of the oldest minerals on Earth, with zircon crystals dating back over 4 billion years found in Australia. However, its use as a gemstone is also ancient. The name "zircon" may come from the Persian zargun, meaning "gold-colored," though the gemstone is most famous for its brilliant blue variety. Blue zircon was particularly popular during the Victorian era in the 19th century. It is important to distinguish natural blue zircon, which is heat-treated to achieve its color, from cubic zirconia, a synthetic diamond simulant that is unrelated. Natural zircon possesses a high refractive index and strong dispersion, giving it a brilliance and fire that can rival diamond. Its historical significance is tied to its use in medieval Europe, where it was believed to bring prosperity and honor and to protect against injury and illness. The gem was thought to encourage restful sleep and ward off evil spirits. Its durability and sparkle have made it a valued gemstone throughout history, though it is less common in the market today than some other blue stones.
Geological Formation and Sources
The three December birthstones originate from vastly different geological processes, which account for their distinct properties and appearances.
Turquoise
Turquoise is a secondary mineral that forms in arid regions where acidic, copper-rich groundwater seeps through pre-existing rocks containing aluminum and phosphorus. Over long periods, this process precipitates turquoise in nodules or veins within host rocks. The most significant sources of turquoise include the southwestern United States (particularly Arizona, New Mexico, and Nevada), Iran (historically the source of the finest "Persian turquoise"), Egypt, China, Mexico, and parts of Central Asia and Africa. The stone often exhibits a matrix—a host rock that remains embedded within the turquoise, creating a distinctive web-like pattern. The color of turquoise varies from sky blue to greenish-blue, depending on the presence of copper (blue) and iron (green) during its formation.
Tanzanite
Tanzanite is found in only one location in the world: the Merelani Hills of Northern Tanzania, near Mount Kilimanjaro. This gemstone is a variety of the mineral zoisite and is formed through a unique geological process. Approximately 585 million years ago, intense heat and pressure from tectonic plate movement altered the chemical composition of the host rock, creating the conditions necessary for zoisite crystals to form. The presence of vanadium and chromium imparts the stone's characteristic blue-violet color. The limited geographic range of its source makes tanzanite exceptionally rare; some estimates suggest the deposits may be exhausted within a few decades, adding to its value and allure.
Zircon
Zircon is a mineral belonging to the group of nesosilicates. It forms as a primary crystal in igneous and metamorphic rocks, such as granite and gneiss. The gemstone variety used in jewelry is primarily mined from placer deposits (sediments concentrated by water action), where the hard, durable zircon crystals have survived weathering and erosion. Major sources of zircon include Australia (which produces most of the world's gem-quality zircon), Cambodia, Sri Lanka, and Thailand. Blue zircon, the variety most associated with December, is typically heat-treated to achieve its blue color; natural blue zircon is extremely rare. The process of heating can sometimes cause the stone to become cloudy or develop fractures if not done carefully, which is a consideration for gemologists and jewelers.
Gemological Properties
Understanding the physical and chemical properties of these gemstones is crucial for identification, valuation, and proper care. The following table summarizes key gemological characteristics for Turquoise, Tanzanite, and Zircon, based on standard references as reflected in the provided sources.
| Property | Turquoise | Tanzanite | Zircon (Blue) |
|---|---|---|---|
| Chemical Formula | CuAl₆(PO₄)₄(OH)₈·4H₂O | Ca₂Al₃(SiO₄)₃(OH) | ZrSiO₄ |
| Crystal System | Triclinic | Orthorhombic | Tetragonal |
| Hardness (Mohs) | 5 - 6 | 6.5 - 7 | 6.5 - 7.5 |
| Specific Gravity | 2.6 - 2.9 | 3.35 | 4.6 - 4.7 |
| Refractive Index | 1.61 - 1.65 | 1.69 - 1.70 | 1.92 - 2.01 |
| Luster | Waxy to vitreous | Vitreous to adamantine | Adamantine |
| Common Treatments | Stabilization, dyeing | Heat treatment (to remove brown hues) | Heat treatment (for color) |
| Notable Features | Often porous, shows matrix | Pleochroism (shows blue and violet) | High dispersion ("fire") |
Turquoise is the softest of the three, with a hardness of 5 to 6 on the Mohs scale. It is relatively porous and often requires stabilization (impregnating with a clear resin or wax) to improve durability and color. Its specific gravity and refractive index are lower than the other two stones, and its luster is typically waxy rather than brilliant. The presence of a matrix (host rock) is common and is a key identifier.
Tanzanite has a hardness of 6.5 to 7, making it suitable for jewelry but requiring some care to avoid scratches. It exhibits strong pleochroism, meaning it can show different colors (blue and violet) when viewed from different crystal directions. Most tanzanite on the market is heat-treated to remove brownish hues and enhance its blue color. Its refractive index is moderate, and its luster is vitreous.
Zircon is the hardest and heaviest of the three, with a hardness of 6.5 to 7.5 and a very high specific gravity. Its most striking feature is its exceptionally high refractive index and strong dispersion, which gives it exceptional brilliance and fire, rivaling that of diamond. Natural blue zircon is rare; most blue zircon in the market is the result of heat treatment applied to brown zircon crystals. Zircon is also known for its high birefringence, which can sometimes cause doubling of facet edges under magnification.
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, these gemstones are rich in symbolism and are believed by many to possess metaphysical properties. These beliefs, while not scientifically proven, are a significant part of their cultural heritage and appeal.
Turquoise is universally regarded as a stone of protection, wisdom, and tranquility. It is said to ground the wearer, promote emotional balance, and ward off negative energy. In many cultures, it is a symbol of friendship and is believed to strengthen relationships. Its historical use as an amulet for travelers and warriors underscores its protective reputation. The belief that it changes color to warn of danger or illness is a longstanding piece of lore.
Tanzanite is often associated with transformation, spiritual awakening, and clarity of mind. Its unique blue-violet color is said to connect the wearer to higher consciousness and to facilitate communication with the spiritual realm. It is believed to encourage a calm, meditative state and to help in navigating life's changes with grace and understanding. Some modern crystal healers attribute it to stimulating the throat and third-eye chakras.
Zircon (particularly blue zircon) is traditionally linked to prosperity, honor, and wisdom. It is believed to enhance mental clarity, focus, and self-confidence. Some traditions hold that zircon promotes restful sleep and protects against nightmares and evil spirits. Its brilliant fire is thought to ignite creativity and passion in the wearer. While these metaphysical properties are part of popular belief, they are not recognized by formal gemology, which focuses on the stone's physical characteristics.
Care and Cleaning
Proper care is essential to maintain the beauty and integrity of December's birthstones. Their varying hardness and chemical compositions dictate specific cleaning and handling guidelines.
Turquoise, due to its softness and porosity, requires the most care. It should be protected from harsh chemicals, including household cleaners, cosmetics, and even sweat, which can cause discoloration and damage. Avoid ultrasonic cleaners and steam cleaning. Clean turquoise jewelry with a soft, damp cloth and mild soap, then dry it thoroughly. Store it separately from harder gems to prevent scratches. It is best to remove turquoise jewelry before physical activities or when swimming.
Tanzanite, with a hardness of 6.5 to 7, is more durable than turquoise but still susceptible to scratches and fractures. It should be cleaned with warm, soapy water and a soft brush. Ultrasonic cleaners and steam cleaning are not recommended, as the vibrations and heat can cause fractures, especially in stones that have been heated or have inclusions. Store tanzanite pieces separately to avoid contact with harder gems.
Zircon, despite its hardness, can be brittle and prone to chipping due to its crystal structure. It is generally safe to clean with warm, soapy water and a soft brush. However, ultrasonic cleaners should be used with caution, as vibrations may cause existing fractures to worsen. Steam cleaning is also not recommended. Zircon should be stored carefully, ideally in a fabric-lined box or a separate compartment in a jewelry box, to protect it from being knocked against other stones.
For all three gemstones, it is advisable to have jewelry inspected periodically by a professional jeweler to check for loose settings or damage, ensuring the stones remain secure and beautiful.
Conclusion
The December birthstones—Turquoise, Tanzanite, and Blue Zircon—offer a remarkable diversity within a shared palette of cool blue hues. Turquoise connects us to the ancient world with its protective lore and earthy matrix patterns. Tanzanite represents the thrill of modern discovery, with its unique color and singular geographic origin. Zircon, an ancient mineral, dazzles with its diamond-like fire and historical associations with prosperity and clarity. Together, they provide December-born individuals with a choice of gemstones that are not only visually stunning but also rich in history, geological wonder, and cultural significance. Understanding their origins, properties, and care requirements allows enthusiasts and collectors to appreciate these gems on a deeper level, ensuring they are cherished for their beauty and legacy. Whether chosen for personal adornment, as a meaningful gift, or for their symbolic attributes, these three azure gems continue to captivate and inspire.
Sources
- December Birthstone Picture
- The traditional birthstones for December are Turquoise, Tanzanite, and Blue Zircon.
- December Birthstones: Blue Topaz, Blue Zircon, Tanzanite and Turquoise
- Meet All Four December Birthstones: Turquoise, Zircon, Tanzanite and Blue Topaz
- December has three traditional birthstones: turquoise, zircon, and tanzanite.
- December birthstone - birthdays between December 1 and 31