For those born in the final month of the year, the gemstone palette is defined by the cool, captivating hues of winter itself. December is unique in the birthstone calendar, offering not one, but three principal gemstones: Tanzanite, Turquoise, and Zircon. Each stone presents a distinct shade of blue, ranging from the sky-like softness of Turquoise to the deep, violet-infused tones of Tanzanite and the brilliant, fiery sparkle of Zircon. This multiplicity provides a rich array of choices, allowing for personal preference in both color and durability. Beyond their aesthetic appeal, these three gems carry profound historical weight, unique geological origins, and a wealth of symbolic meanings that have resonated with humanity for millennia.
The primary distinction among these stones lies in their chemical composition, hardness, and optical characteristics. Tanzanite, a relative newcomer to the gemological world, is celebrated for its remarkable trichroism and rarity. Turquoise, one of the oldest known gemstones, is prized for its opaque, robin's-egg blue color and distinctive matrix patterns. Zircon, often confused with the synthetic cubic zirconia, is a natural, high-refractive-index mineral known for its exceptional brilliance and durability. Understanding these three stones requires an exploration of their individual histories, the specific geological conditions that create them, and the practical considerations for their use in jewelry. This guide delves into the science and lore of December's azure trio, providing a definitive resource for enthusiasts, collectors, and anyone captivated by these blue treasures.
History and Lore
The historical narratives of December's birthstones are as varied as their colors, spanning ancient civilizations and diverse cultures. Each stone has been woven into the fabric of human history, acquiring layers of meaning and symbolism along the way.
Turquoise: The Ancient Talisman
Turquoise stands as the most ancient of the three, with a history stretching back thousands of years. Its name is derived from the French phrase pierre tourques, or "Turkish stone," reflecting its introduction to Europe from the Ottoman Empire. However, its use predates this significantly. The provided sources indicate that Chinese artisans carved turquoise more than 3,000 years ago, and the gemstone was a prominent feature in the adornments of ancient Egyptian pharaohs. The famous burial mask of Tutankhamun, for instance, was heavily inlaid with this vibrant blue stone.
Throughout history, Turquoise has been overwhelmingly associated with protection and good fortune. Hindu mystics believed that gazing upon a turquoise after seeing the new moon would ensure fantastic wealth. In the 13th century, a widespread belief held that the stone could protect the wearer from falling, particularly from horses, and that it would shatter at the approach of disaster, thereby sacrificing itself to save its owner. This protective quality was also central to Native American cultures. The Apache, for example, believed turquoise could be found by following a rainbow to its end and that it imbued the bearer with invincibility. These historical beliefs underscore Turquoise's enduring role as a powerful protective talisman.
Zircon: The Stone of Wisdom and Prosperity
Zircon has a long and often misunderstood history. For centuries, it has been prized for its brilliance and fire, often rivaling that of diamonds. While the sources mention that zircon is historically associated with prosperity, wisdom, and a sense of balance, its lore is less detailed than that of Turquoise. In medieval Europe, zircon was believed to induce sound sleep, ward off evil spirits, and promote riches and honor. It was a stone of travelers, thought to protect them on their journeys and bring them home safely. Its association with wisdom aligns with its sparkling clarity, which has long been seen as a metaphor for a clear mind and sound judgment. The gem is also linked to the 4th wedding anniversary, symbolizing a stable and prosperous union.
Tanzanite: The Modern Marvel
Tanzanite is the newest addition to the birthstone list, having been discovered in 1967. Its history is therefore not one of ancient lore but of modern discovery and rapid ascent to prominence. Found exclusively in a small area near Mount Kilimanjaro in Tanzania, its origin story is as unique as the gem itself. The Maasai people, who live near the discovery site, attributed spiritual significance to the stone, believing it brought about a new way of life and a higher level of consciousness. This modern interpretation aligns with the gem's symbolic meaning of transformation and new beginnings. Its recognition as a birthstone shortly after its discovery cemented its place in the contemporary jewelry market, appealing to those seeking a gemstone with a fresh narrative and a rare, alluring color.
Geological Formation and Sources
The origins of these gemstones are a testament to the diverse and specific conditions required to form precious minerals deep within the Earth.
Tanzanite: A Singular Geological Anomaly
Tanzanite's existence is a geological fluke. It is a variety of the mineral zoisite, and its formation required a unique set of circumstances that occurred only once in geological history. The conditions for its creation are found in a mere four-square-kilometer area at the Merelani Hills near Mount Kilimanjaro in Tanzania. This extreme rarity is a primary driver of its value. The sources confirm that tanzanite is "found only in a small area near Mount Kilimanjaro," making it "one of the rarest gemstones in the world." The geological process involved the metamorphism of rocks under specific temperature and pressure conditions, which introduced vanadium, the element responsible for the stone's signature blue-to-violet color.
Turquoise: A Global Mineral
In stark contrast to Tanzanite, Turquoise is found worldwide. The sources describe it as a hydrated copper aluminum phosphate that forms in arid regions where acidic, copper-rich water seeps through rocks and reacts with minerals containing aluminum and phosphorus. This process occurs in many locations globally. While the sources do not list specific modern mining locations, they confirm its "worldwide" geographic origin. Famous historical sources include the Sinai Peninsula in Egypt and the American Southwest, which remains a significant source for high-quality Turquoise today.
Zircon: An Ancient Detrital Mineral
Zircon is one of the oldest minerals on Earth, with crystals found in Australia dating back over 4.4 billion years. It is a zirconium silicate that forms in igneous and metamorphic rocks. Over geological time, these hard, durable crystals are released from their host rock and transported by water, eventually settling in sedimentary deposits. This is why many of the world's gem-quality zircons are mined from placer deposits (alluvial mines). The sources identify Sri Lanka, Cambodia, and Australia as key geographic origins for the blue zircon used in jewelry.
Gemological Properties
A scientific understanding of each stone's properties is essential for both identification and proper care. The following table, compiled from the physical property data in the sources, provides a clear comparison.
| Property | Tanzanite | Turquoise | Zircon |
|---|---|---|---|
| Mineral Species | Zoisite | Hydrated copper aluminum phosphate | Zirconium silicate |
| Chemical Formula | Ca₂Al₃(SiO₄)₃(OH) | - | ZrSiO₄ |
| Color | Blue to violet-blue, purple | Blue to green-blue | Blue (for December), also colorless, yellow, red, green |
| Hardness (Mohs Scale) | 6 - 7 | 5 - 6 | 7.5 |
| Transparency | Transparent to translucent | Opaque | Transparent to translucent |
| Refractive Index | 1.691 - 1.700 | 1.61 - 1.65 | 1.925 - 1.984 |
| Crystal System | Orthorhombic | Triclinic | Tetragonal |
| Specific Gravity | 3.35 | 2.6 - 2.8 | 3.90 - 4.73 |
Detailed Analysis of Properties
Tanzanite is known for its remarkable trichroism, a property where the gem exhibits three different colors—blue, purple, and burgundy—when viewed from different angles. This characteristic is a key identifier and a major part of its appeal. With a hardness of 6 to 7 on the Mohs scale, it is suitable for jewelry but requires care to avoid chipping. It is almost always heat-treated to produce its stable blue and violet colors.
Turquoise is an opaque gem, meaning light does not pass through it. Its color ranges from sky blue to greenish-blue, often containing veins of matrix (remnants of the host rock). Its hardness of 5 to 6 makes it relatively soft and susceptible to scratching and chemical damage. Many commercial turquoise stones are "stabilized," a treatment where the stone is impregnated with a resin to increase its durability and color uniformity.
Zircon is the hardest of the trio, with a Mohs hardness of 7.5, making it quite durable for most jewelry applications. Its most important optical property is its high refractive index, which gives it a brilliant sparkle and fire that can rival a diamond. Blue zircon is typically produced by heat-treating brown zircon crystals. It is important to note that zircon is a natural gemstone, entirely different from the synthetic material cubic zirconia (CZ).
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, all three of December's birthstones are steeped in symbolism and are believed by many to possess metaphysical properties.
A common thread linking Tanzanite, Turquoise, and Zircon is their association with wisdom and mental clarity. They are thought to help the wearer think more clearly and make sound decisions. Protection is another powerful theme, particularly for Turquoise, which has served as a protective amulet for centuries. Tanzanite is strongly linked to transformation and spiritual growth, believed to facilitate a deeper connection to one's higher self and encourage a new way of living. Zircon is often associated with prosperity and success, making it a popular stone for those seeking to achieve their goals. Furthermore, all three stones have been historically attributed with healing properties, believed to support the body's natural healing processes and promote overall well-being.
Care and Cleaning
Proper care is paramount to maintaining the beauty and longevity of these gemstones, and their differing properties necessitate distinct approaches.
Tanzanite: With a hardness of 6-7 and potential for chipping, Tanzanite requires gentle handling. It is recommended for pieces that are less likely to receive hard knocks, such as earrings and pendants. Cleaning should be done with warm, soapy water and a soft brush. Avoid ultrasonic cleaners and steam, as the heat and vibrations can cause damage.
Turquoise: As the softest and most porous of the three, Turquoise is the most delicate. It is sensitive to chemicals, including those found in lotions, cosmetics, and even some soaps, which can dull its color and luster. It should be cleaned only with a soft, dry cloth. Warm, soapy water can be used sparingly, but it must be dried thoroughly immediately. Avoid all chemicals and harsh cleaning methods.
Zircon: Although Zircon is relatively hard (7.5), it can be brittle and may be susceptible to chipping at its facets. It is also sensitive to sharp impacts. Some zircon may also be sensitive to heat, so it is best to avoid extreme temperature changes. Cleaning with warm, soapy water and a soft brush is safe. As with Tanzanite, it is best to avoid ultrasonic and steam cleaning.
Conclusion
The birthstones of December—Tanzanite, Turquoise, and Zircon—offer a remarkable trio of blue gems, each with a distinct identity. From the ancient, protective talisman of Turquoise to the rare, transformative allure of Tanzanite and the brilliant, wise sparkle of Zircon, these stones provide a wealth of options for those born in the month. Their diverse origins, from the single small deposit of Tanzanite in Tanzania to the global presence of Turquoise, reflect the varied geological wonders of our planet. While they share a common color palette and symbolic associations with wisdom and clarity, their individual gemological properties demand specific care to preserve their unique beauty. Ultimately, the choice among them is a matter of personal preference, balancing the desired shade of blue with considerations of durability, history, and the unique story each gemstone tells.