The month of December holds a unique distinction in the world of gemology. While most months are assigned a single birthstone, December is adorned with three official, brilliant blue gemstones: Turquoise, Zircon, and Tanzanite. This trio offers individuals born in the final month of the year a remarkable spectrum of choices, ranging from ancient earth-mined treasures to a relatively recent discovery celebrated for its modern allure. The tradition of associating specific gems with birth months has evolved over millennia, but the December selection stands out for its combination of historical depth, geological diversity, and vibrant coloration that mirrors the cool, clear skies of winter.
The significance of these stones goes beyond mere aesthetics. Each gem possesses a distinct geological origin, a unique set of physical properties, and a rich tapestry of cultural lore that has accumulated over centuries. Turquoise is perhaps the most historically significant, revered for thousands of years across numerous civilizations. Zircon, often confused with the synthetic cubic zirconia, is one of the oldest minerals on Earth, boasting a brilliance that rivals that of a diamond. Tanzanite is the newcomer, a member of the zoisite family discovered only in the 20th century, yet it has rapidly ascended to become a prized gemstone due to its extraordinary violet-blue hue and relative rarity. Together, these three stones provide a comprehensive look at the history and science of birthstones, offering options that appeal to lovers of ancient tradition, scientific curiosity, and contemporary fashion.
This article will explore the rich history, geological formation, gemological properties, and symbolism associated with Turquoise, Zircon, and Tanzanite. By delving into the specific characteristics of each stone, we can appreciate why these three gems have been collectively chosen to represent the festive and reflective month of December.
History and Lore: A Journey Through Time
The tradition of birthstones is ancient, with roots traceable to the breastplate of Aaron described in the Old Testament, which featured twelve stones representing the twelve tribes of Israel. The practice of associating a specific gem with an individual's birth month gained popularity in Europe and North America during the 18th and 19th centuries. However, the specific stones assigned to December have not been static. Originally, Turquoise and Zircon were the primary gems associated with the month. The 20th century saw the addition of Tanzanite, and in some lists, Blue Topaz, reflecting the evolving nature of the tradition as new gemstones are discovered and gain commercial prominence. Sources note that December is the only month with four officially recognized birthstones in some modern lists, including Tanzanite, Turquoise, Blue Zircon, and Blue Topaz.
Turquoise: The Ancient Talisman
Turquoise is widely regarded as one of the world's oldest known gemstones. Its history is as colorful as the stone itself. The very name "Turquoise" is derived from the French phrase pierre turquoise, meaning "stone of Turkey." This etymology traces back to the gem's introduction to Europe from Turkish bazaars, where it was traded. However, the stone's origins lie far from Turkey. It has been mined and revered for over 5,000 years. Ancient Egyptians adorned themselves with Turquoise jewelry, including the famous burial mask of Tutankhamun, which was inlaid with the gem. In Persian culture, Turquoise was considered a protective stone, worn to ward off unnatural death and ensure good fortune. The Native American cultures of the American Southwest, particularly the Navajo, Zuni, and Pueblo peoples, have a profound artistic and spiritual connection to Turquoise, incorporating it into intricate silver and beadwork that is celebrated globally.
Zircon: The Diamond Impostor and Ancient Mineral
Zircon is frequently misunderstood due to its phonetic similarity to "cubic zirconia," a synthetic diamond simulant. However, natural Zircon is a distinct, naturally occurring mineral (zirconium silicate) and is one of the oldest minerals on Earth, with some specimens dating back over 4.4 billion years. For centuries, colorless Zircon was mistaken for diamond due to its high refractive index and exceptional brilliance. In the Middle Ages, it was believed to induce sound sleep, ward off evil spirits, and bring prosperity and wisdom. Its use as a birthstone is long-standing, and its sparkling appearance has made it a popular, though often overlooked, gem in jewelry.
Tanzanite: The Gem of the 20th Century
In stark contrast to the ancient lineage of Turquoise and Zircon, Tanzanite is a distinctly modern gem. It was not discovered until the mid-20th century. The gem is a variety of the mineral zoisite and is found in only one location on the globe: the Merelani Hills of Northern Tanzania. Its discovery is attributed to a Masai tribesman in 1967, and it was later identified as a distinct gemstone variety. Tiffany & Co. recognized its potential and introduced it to the world in 1968, naming it "Tanzanite" after its country of origin. Its rapid rise to prominence led to its official designation as a December birthstone in 2002 by the American Gem Trade Association (AGTA), making it the newest addition to the traditional birthstone list. Its story is one of modern exploration and the serendipitous discovery of a unique geological treasure.
Geological Formation and Mining Locations
The three December birthstones are formed through vastly different geological processes and are sourced from distinct regions of the world, contributing to their unique characteristics and value.
Turquoise: A Hydrated Copper Mineral
Turquoise is a secondary mineral that forms when water containing copper and aluminum seeps through rocks. This process occurs in arid regions where the evaporation of groundwater concentrates these minerals into nodules or veins. The presence of copper dictates the gem's signature blue color, while iron and chromium can influence greenish hues. The famous "matrix" varieties of Turquoise, such as those from the American Southwest, contain remnants of the host rock (often pyrite or limonite) embedded within the blue mineral, creating intricate spiderweb patterns. * Primary Sources: The United States (Arizona, Nevada, New Mexico) is a historically significant source, particularly for "Sleeping Beauty" and "Kingman" Turquoise. Other major sources include Iran (known for its pure, sky-blue "Persian Turquoise"), China, and Egypt.
Zircon: A Primary Mineral in Pegmatites
Unlike Turquoise, Zircon is a primary mineral, meaning it is one of the first crystals to solidify from cooling magma. It is commonly found in igneous and metamorphic rocks. Large, gem-quality crystals are often extracted from pegmatites—coarse-grained igneous rocks—or placer deposits, where the durable Zircon crystals have been weathered from their original host rock and concentrated by water action. * Primary Sources: Australia is the leading producer of Zircon, known for its brownish and blue-hued stones. Other significant sources include Cambodia, Sri Lanka, Thailand, and parts of Africa. Heat treatment is commonly used to transform brown Zircon into the popular blue and colorless varieties found in jewelry.
Tanzanite: A Product of Unique Geology
Tanzanite's formation is a geological rarity. It is a member of the zoisite group and gets its vivid blue-to-violet color from the presence of vanadium. The gem is found exclusively in a small, four-square-kilometer mining area in the Merelani Hills of Northern Tanzania. The geological conditions required for its formation are believed to be the result of a tectonic shift and metamorphic event that occurred roughly 585 million years ago, an event unique to this specific location. * Primary Source: The Merelani Hills of Tanzania. Due to its limited geographic origin, Tanzanite is considered at least a thousand times rarer than Diamond. Mining in this region is challenging, and the finite nature of the supply contributes to the stone's value and allure.
Gemological Properties
Understanding the physical and chemical properties of these gems is essential for jewelers, collectors, and consumers. These properties dictate a stone's durability, appearance, and care requirements.
| Property | Turquoise | Zircon | Tanzanite |
|---|---|---|---|
| Chemical Composition | Hydrated copper/aluminum phosphate | Zirconium silicate (ZrSiO₄) | Calcium aluminum hydroxyl sorosilicate |
| Color | Sky-blue to greenish-blue; often contains a dark matrix | Colorless, yellow, brown, red, blue; blue is most popular for jewelry | Blue to violet-blue; often pleochroic (shows different colors from different angles) |
| Hardness (Mohs Scale) | 5.0 - 6.0 | 6.5 - 7.5 | 6.5 - 7.0 |
| Crystal System | Triclinic | Tetragonal | Orthorhombic |
| Refractive Index | 1.610 - 1.650 | 1.925 - 2.015 | 1.691 - 1.700 |
| Luster | Waxy to subvitreous | Adamantine (diamond-like) to vitreous | Vitreous |
Hardness and Durability
- Turquoise is the softest of the three, with a hardness of 5 to 6 on the Mohs scale. This makes it susceptible to scratching and damage from chemicals, lotions, and even skin acids. It is often stabilized (treated with resin) to improve its hardness and color.
- Zircon is the hardest of the trio, with a hardness up to 7.5. While it is durable enough for most jewelry, it can be brittle and prone to chipping if struck with force due to its tetragonal crystal structure.
- Tanzanite has a hardness of 6.5 to 7.0, making it a relatively durable gem. However, its cleavage (the tendency to break along flat planes) is perfect in one direction, meaning it can be damaged by a sharp blow. This property requires careful setting and handling.
Color and Clarity
The defining characteristic of the December trio is their blue coloration, though the source and manifestation of this color differ. * Turquoise is typically an opaque gem, prized for its uniform color and the unique patterns of its matrix. Transparency is rare and generally not valued in Turquoise. * Zircon is known for its high refractive index and strong dispersion ("fire"), which gives it a brilliant sparkle. Blue Zircon, the most popular variety for jewelry, is almost always produced by heat-treating brown zircon. These stones are typically eye-clean. * Tanzanite is valued for its transparency and deep, saturated color. It is almost always eye-clean, with inclusions being rare. A key gemological feature of Tanzanite is its strong trichroism, where a single stone can exhibit three different colors: blue, violet, and reddish-brown. Gem cutters must orient the stone carefully to display the desirable blue-violet hue.
Symbolism and Metaphysical Beliefs
Across cultures and centuries, gemstones have been imbued with symbolic meaning and attributed with healing or protective powers. The December birthstones are rich in such lore.
Turquoise: The Master Healer
Turquoise is arguably one of the most symbolically potent stones. It has long been associated with protection, good fortune, and healing. Ancient warriors would attach Turquoise to their weapons or armor, believing it would deflect blows and prevent injury. In many cultures, it is seen as a stone of communication, promoting honesty and clarity of thought. Metaphysically, Turquoise is often linked to the throat chakra, supporting clear and effective self-expression. It is also believed to be a grounding stone that can absorb negative energy and balance mood swings, fostering a sense of tranquility.
Zircon: The Stone of Wisdom and Virtue
Zircon has been historically associated with wisdom, wealth, and honor. It was believed to promote honor and purity, and to help its wearer achieve wisdom through spiritual balance. Some legends suggest that Zircon can help one discern who is telling the truth and who is being deceitful. It is also associated with sound sleep and the alleviation of nightmares. In terms of its metaphysical properties, Zircon is thought to stimulate the root and crown chakras, providing a strong spiritual grounding while simultaneously connecting the wearer to higher consciousness.
Tanzanite: The Stone of Transformation
As a modern gem, Tanzanite's symbolism is more contemporary but no less powerful. It is known as the "stone of transformation," believed to facilitate a higher consciousness, intuition, and spiritual perception. It is associated with the throat and crown chakras, aiding in clear communication and spiritual awakening. Many believe that Tanzanite encourages a calm and compassionate demeanor, helping to alleviate stress and panic. Its discovery in modern times links it to themes of new beginnings and the journey of the soul toward enlightenment.
Care and Cleaning
The varying hardness and chemical composition of these gems necessitate different care procedures to ensure their longevity and beauty.
Caring for Turquoise
Due to its porosity and relatively low hardness, Turquoise requires the most care. * Cleaning: Use warm, soapy water and a soft brush. Avoid ultrasonic cleaners and steam cleaners, as heat and vibrations can damage the stone or any stabilizing treatments. Never use bleach or other harsh chemicals. * Storage and Wear: Store it separately to prevent scratching. Avoid prolonged exposure to direct sunlight, cosmetics, lotions, and skin oils, which can cause the stone to discolor or become "greened" over time.
Caring for Zircon
Zircon is durable but can be brittle. * Cleaning: The safest method is warm, soapy water with a soft brush. While it can generally withstand an ultrasonic cleaner, it is not recommended for stones that may have fractures. Avoid sudden temperature changes, which can cause the stone to crack. * Storage: Store it carefully, ideally wrapped in a soft cloth, to prevent it from scratching other gems or being scratched by harder stones like sapphire or diamond.
Caring for Tanzanite
Tanzanite's perfect cleavage makes it vulnerable to damage. * Cleaning: Use only warm, soapy water and a soft brush. Do not use ultrasonic cleaners or steam cleaners under any circumstances, as the vibrations and heat can cause the stone to fracture. * Storage: Store Tanzanite jewelry in a soft pouch or a separate compartment in a jewelry box to protect it from harder gems. It is advisable to remove Tanzanite rings during activities that could lead to impact, such as gardening or sports.
Conclusion
The birthstones of December—Turquoise, Zircon, and Tanzanite—offer a compelling narrative of geological rarity, historical significance, and aesthetic diversity. From the opaque, sky-blue talisman of ancient civilizations to the brilliant, diamond-like sparkler of antiquity and the modern, violet-blue marvel of Tanzania, this trio provides a gem for every preference and story. They are united by their captivating blue hues, reminiscent of the winter month they represent, yet each stands apart in its chemical makeup, physical resilience, and cultural legacy. For those born in December, the choice between these three gems is not merely a matter of color but an opportunity to connect with a rich heritage that spans from the dawn of human history to the frontiers of modern gemological discovery. Whether chosen for its protective lore, its brilliant fire, or its transformative symbolism, a December birthstone is a timeless treasure.