December boasts a remarkable array of birthstones – turquoise, blue zircon, tanzanite, and lapis lazuli – each offering a unique shade of blue and a rich history. These gemstones, cherished for millennia, represent a diverse spectrum of geological origins, cultural significance, and aesthetic appeal. This article delves into the fascinating world of December’s birthstones, exploring their historical use, gemological properties, and enduring symbolism.
History and Lore
The tradition of associating gemstones with specific months dates back to ancient times, evolving from biblical connections and early cultural practices. These colored gems were not merely adornments but were believed to bestow beneficial powers upon their wearers. The practice of wearing birthstones wasn’t a recent fashion trend, but rather a custom rooted in medieval times.
Turquoise, perhaps the most recognizable of December’s stones, has been prized for over 5,000 years. Ancient Egyptians, pharaohs, and rulers adorned themselves with turquoise, believing it possessed protective qualities. From the 13th century onward, it was thought to safeguard against falls, particularly from horses, and even to warn of impending disaster by fracturing. In Hindu mysticism, viewing turquoise after a new moon was believed to bring great wealth.
Lapis lazuli, another traditional December birthstone, held a place of high esteem in ancient civilizations. Its deep azure tones were associated with wisdom and royalty, considered a stone of truth and enlightenment capable of enhancing intellectual abilities.
While turquoise and lapis lazuli represent the traditional choices, blue zircon and tanzanite have emerged as modern alternatives. The adoption of multiple birthstones for each month allows for a wider range of preferences and budgets.
Geological Formation and Sources
The origins of these December birthstones are geographically diverse. Turquoise forms in relatively dry, arid regions, often in the vicinity of copper deposits. Historically, the Nishapur district of Iran was a significant source, producing turquoise renowned for its intense, even blue color – often described as “robin’s egg blue,” “sky blue,” or “Persian blue.” Today, China is the world’s largest producer, with most gem-quality turquoise originating from Hubei Province. Within the United States, Arizona and Nevada are currently the primary sources, with historically important mines like Kingman in Arizona and the now-closed Sleeping Beauty mine.
Zircon, unlike turquoise, is found in a variety of geological settings, including igneous, metamorphic, and sedimentary rocks. Its formation involves complex processes within the Earth’s crust.
Tanzanite, a relatively recent discovery, is found in a very limited geographical area: the Merelani Hills of northern Tanzania. This exclusivity contributes to its value and desirability.
Lapis lazuli is typically found in metamorphic rocks, often associated with contact aureoles around igneous intrusions. Historically, Afghanistan has been a major source of lapis lazuli, though it is also found in other locations, including Russia and Chile.
Gemological Properties
Each December birthstone possesses distinct gemological properties that contribute to its unique character.
Turquoise is a semi-translucent to opaque gem, ranging in color from blue to green. A defining characteristic is the presence of matrix – remnants of the host rock – which often appears as veins running through the stone. Its quality is graded based on color, matrix, and texture, with dense textures exhibiting better polish luster. The most valuable color is a bright, even “robin’s egg” blue.
Blue Zircon is a silicate mineral that exhibits a wide range of colors, but blue is the most popular and valuable. Blue zircon is almost always heat-treated to achieve its color. Zircon’s color can be affected by radioactive elements over time, leading to changes in its crystalline structure and appearance. “High zircon” specimens, typically blue or colorless, are preferred for jewelry.
Tanzanite is a variety of the mineral zoisite, known for its trichroism – displaying different colors depending on the viewing angle. The most valuable tanzanite exhibits a vibrant, pure blue color, though purplish-blue and violet-blue shades are also sought after. Strong pleochroism, or color change, enhances its value.
Lapis Lazuli is not a single mineral but a rock composed primarily of lazurite, along with other minerals like calcite and pyrite. Its characteristic deep blue color is due to the presence of lazurite.
The following table summarizes key properties:
| Gemstone | Chemical Formula | Color(s) | Hardness (Mohs) | Transparency |
|---|---|---|---|---|
| Turquoise | CuAl6(PO4)4(OH)8·4H2O | Blue, Green | 5-6 | Opaque |
| Blue Zircon | ZrSiO4 | Blue (typically treated) | 6.5-7.5 | Transparent to Opaque |
| Tanzanite | Ca2Al3(SiO4)3(OH) | Blue, Violet, Purple | 6-7 | Transparent |
| Lapis Lazuli | (Na,Ca)9Al6Si6O24(SO4,S,Cl)2 | Deep Blue | 5-6 | Opaque |
Symbolism and Metaphysical Beliefs
Throughout history, each of these December birthstones has been imbued with symbolic meaning. Turquoise has long been associated with protection, good fortune, and health. Lapis lazuli represents wisdom, truth, and enlightenment. Blue zircon is often linked to prosperity and honor. Tanzanite, a more recent addition to the birthstone list, is believed to promote communication and intuition.
These beliefs, while not scientifically verifiable, contribute to the enduring appeal of these gemstones. They offer a sense of connection to the past and a belief in the power of natural beauty.
Care and Cleaning
Proper care is essential to maintain the beauty of December’s birthstones. Turquoise, being relatively soft, is susceptible to scratches and damage from harsh chemicals. It should be cleaned with a soft cloth and mild soap and water. Avoid ultrasonic cleaners and harsh cleaning agents.
Zircon, with its higher hardness, is more durable but can still be chipped or scratched. It can be cleaned with warm, soapy water and a soft brush.
Tanzanite is also relatively durable but can be damaged by sudden temperature changes. It should be cleaned with warm, soapy water and a soft cloth.
Lapis lazuli, being somewhat porous, should be protected from prolonged exposure to liquids. It can be cleaned with a soft cloth and mild soap and water.
Conclusion
December’s birthstones – turquoise, blue zircon, tanzanite, and lapis lazuli – represent a captivating blend of history, geology, and symbolism. From the ancient protective powers attributed to turquoise to the modern allure of tanzanite, these gemstones continue to fascinate and inspire. Whether chosen for their aesthetic beauty, their historical significance, or their perceived metaphysical properties, these December birthstones offer a unique and meaningful connection to the natural world.