For those born in December, the choice of a birthstone is not a singular decision but a celebration of a vibrant triad: the ancient, opaque Turquoise; the recently discovered, vivid Tanzanite; and the brilliantly faceted, color-diverse Zircon. These three gemstones, each with a distinct geological origin and cultural narrative, collectively define the modern birthstone list for the twelfth month. While their colors range from the robin's egg blue of Turquoise to the deep violet-blue of Tanzanite and the rainbow of Zircon, they share a common thread of historical significance and symbolic meaning that has captivated civilizations for millennia. This article delves into the rich tapestry of history, geology, and lore surrounding these three December birthstones, providing a comprehensive guide for gemstone enthusiasts, jewelry buyers, and students of gemology.
Historical Lore and Cultural Significance
The concept of birthstones is ancient, with roots tracing back to the breastplate of Aaron described in the Old Testament, which featured twelve stones representing the tribes of Israel. This tradition evolved over centuries, with various cultures attributing specific gems to months based on historical, astrological, or calendrical systems. The modern standardized list of birthstones, as recognized in the United States, was largely established by the American National Association of Jewelers in 1912.
Turquoise, the traditional December birthstone, boasts one of the longest histories of use among all gemstones. Its name derives from the French expression “pierre tourques,” meaning “Turkish stone,” which originated in the 13th century, reflecting the trade routes through which it reached Europe. Ancient civilizations held Turquoise in high esteem. The pharaohs of ancient Egypt adorned themselves with it, and Chinese artisans were carving it more than 3,000 years ago. Some sources indicate that Turquoise has been mined in the Sinai region of Egypt as early as 5500 BCE, and burial sites in western Iran containing Turquoise date back to 7000 BCE, making it a contender for the world's oldest gem material. Its significance was not merely aesthetic; it was deeply embedded in spiritual and practical beliefs. In ancient Egypt, it was called “mefkat,” meaning “joy” and “delight.” From the 13th century onward, it was believed to protect the wearer from falls, particularly from horses, and would allegedly break into several pieces as a warning of impending disaster. Hindu mystics believed that seeing a turquoise after beholding the new moon would ensure fantastic wealth. For Native American tribes, such as the Apache, Turquoise held profound spiritual importance; one legend suggested it could be found by following a rainbow to its end. These diverse cultural beliefs underscore Turquoise's role as a talisman for protection, health, and good fortune.
In stark contrast to Turquoise's ancient lineage, Tanzanite is a gemstone of the modern era. Discovered only in 1967, it is the youngest of the December birthstones. Its origin story is unique and geographically specific; it is found exclusively in a single, small area in Tanzania, making it one of the rarest gemstones on Earth. This recent discovery means Tanzanite lacks the deep, multi-millennial history of Turquoise, but it has rapidly accumulated its own lore. Its vibrant, blue-to-purple hues, which exhibit a striking trichroic effect (showing blue, violet, and burgundy tones depending on the viewing angle), have been associated with themes of transformation, spiritual awakening, and emotional balance. As a gemstone that came to prominence in the late 20th century, it represents a new chapter in the story of birthstones, appealing to those drawn to its unique beauty and contemporary symbolism.
Zircon occupies a fascinating middle ground, with a history that stretches back centuries, though its identity has often been clouded by confusion with other gems. The term “zircon” is derived from the Persian words “zargun,” meaning “gold-colored.” For centuries, Zircon has been admired for its exceptional brilliance and fire, which can rival that of diamond. However, its high refractive index and dispersion have led to it being mistaken for more expensive gems throughout history. Blue Zircon, in particular, is a popular modern birthstone for December. While Zircon has been used in jewelry for a long time, its specific association with December is part of the modern birthstone list. Its rainbow of color varieties—including blue, yellow, green, red, and brown—provides a diverse palette, with the blue variety being the most sought-after for December-born individuals.
Geological Formation and Global Sources
The origins of these three gemstones are as varied as their histories, reflecting different geological processes and mining locations.
Turquoise is a secondary mineral formed through the interaction of water containing copper, aluminum, and phosphorus with pre-existing rocks. It is typically found in arid regions where these elements have concentrated. The presence of specific trace elements dictates its color: copper imparts the classic blue, while iron and zinc contribute greenish and yellowish hues, respectively. The gemstone is often porous and contains a matrix—veins of the host rock (such as chert or limonite) that are remnants of its formation. Major sources of Turquoise include Iran (historically the source of the finest “Persian Blue” material), China, Mexico, the Middle East, Kazakhstan, and the United States (particularly Arizona, Nevada, and New Mexico). The United States has a rich history of Turquoise mining, especially by Native American cultures.
Tanzanite is a variety of the mineral zoisite. Its formation is exceptionally rare, requiring a unique combination of geological conditions. It is found in the Merelani Hills of northern Tanzania, near the base of Mount Kilimanjaro. The gemstone is believed to have formed approximately 585 million years ago during a tectonic event that subjected the zoisite to intense heat and pressure, causing the introduction of vanadium (which gives it its blue color) and subsequent rapid cooling. This specific geological setting has not been found anywhere else in the world, making Tanzanite's source exclusive. The mining area is small, and the gemstone is often found in crystals that are cut into calibrated sizes for jewelry.
Zircon is a zirconium silicate (ZrSiO₄) and is one of the oldest minerals on Earth, with some crystals dating back billions of years. It forms in igneous rocks (like granite) and metamorphic rocks, and it can also be found in alluvial deposits (sediments) from which it is eroded. Zircon is a common accessory mineral in many rocks but gem-quality material is rarer. The blue variety of Zircon, which is popular for December, is typically heat-treated brown or yellow zircon to achieve its stable blue color. Major sources of Zircon include Thailand, Cambodia, Sri Lanka, Australia, and the United States (particularly in the state of North Carolina). Its durability and resistance to weathering allow it to survive in sedimentary deposits, making it a common find in placer mining operations.
Gemological Properties
Understanding the physical and chemical properties of these gemstones is crucial for identification, valuation, and care. The following table summarizes key gemological data for Turquoise, Tanzanite, and Zircon, based on the provided sources.
| Property | Turquoise | Tanzanite | Zircon (Blue) |
|---|---|---|---|
| Chemical Formula | CuAl₆(PO₄)₄(OH)₈·4H₂O | Ca₂(Al,Fe)₃(SiO₄)₃(OH) | ZrSiO₄ |
| Crystal System | Triclinic | Orthorhombic | Tetragonal |
| Color | Blue to green, often with brown/black matrix. | Blue to violet (trichroic: blue, violet, burgundy). | Blue (heat-treated from brown/yellow), also yellow, green, red, brown. |
| Hardness (Mohs) | 5 - 6 | 6.5 - 7 | 6.5 - 7.5 |
| Refractive Index | 1.61 - 1.65 | 1.69 - 1.70 | 1.92 - 1.98 (high) |
| Specific Gravity | 2.60 - 2.90 | 3.35 | 4.6 - 4.7 (very high) |
| Luster | Waxy to dull | Vitreous (glassy) | Adamantine (brilliant) |
| Transparency | Semi-translucent to opaque | Transparent to translucent | Transparent |
| Common Treatments | Waxing, dyeing, stabilization (impregnation). | Heating (to remove brown components). | Heating (to achieve blue color). |
Turquoise is a relatively soft gemstone (Mohs 5-6), making it susceptible to scratching and damage. Its porous nature means it is often treated with wax, dye, or stabilization (impregnation with a clear resin or plastic) to enhance its color, durability, and polish. Stabilized Turquoise is more resistant to color change from body oils and moisture, which can otherwise cause the stone to darken or discolor over time. The most prized colors are uniform shades of robin's egg blue, sky blue, and Persian blue.
Tanzanite has a hardness of 6.5 to 7 on the Mohs scale, making it suitable for jewelry but still requiring care to avoid knocks and scratches. Its most distinctive feature is its strong trichroism, where a single crystal shows three different colors from different crystallographic directions. Most Tanzanite on the market is heat-treated to remove brownish components and enhance its desirable blue-violet hues. This treatment is permanent and is now considered a standard industry practice.
Zircon is a hard and durable gemstone, with a Mohs hardness of 6.5 to 7.5. Its most remarkable property is its high refractive index and dispersion, which gives it exceptional brilliance and fire, often exceeding that of diamond. The blue variety commonly used for December birthstones is typically produced by heating brown or yellow zircon at high temperatures in a controlled environment. This heat treatment is stable and permanent. Zircon's high specific gravity (4.6-4.7) makes it feel noticeably heavy for its size, which is a key identification clue.
Symbolism and Metaphysical Beliefs
The symbolism attached to these gemstones is rich and varied, drawing from centuries of cultural beliefs and modern interpretations.
Turquoise has been a symbol of protection, healing, and good fortune across numerous cultures. Ancient Egyptians believed it brought protection and power, while in medieval Europe, it was thought to safeguard the wearer from injury and illness. Its association with the sky and water in many Native American cultures links it to life-giving forces and spiritual guidance. Modern metaphysical beliefs attribute Turquoise with the ability to balance the chakras, promote emotional calm, and enhance communication. It is often called the “master healer” stone, believed to absorb negative energy and protect the environment.
Tanzanite, as a relatively new gemstone, has developed a modern symbolism focused on transformation and spiritual growth. Its striking color is associated with the higher chakras, particularly the throat and third eye chakras, believed to facilitate clear communication and intuition. Many view it as a stone of new beginnings, encouraging the wearer to embrace change and pursue their destiny. Its discovery in a single location adds to its aura of uniqueness and rarity, symbolizing individuality and purpose.
Zircon has historically been associated with wisdom, honor, and purity. In some traditions, it was believed to promote prosperity and help the wearer achieve their goals. The blue variety, in particular, is linked to tranquility and peace. Its fiery brilliance is thought to inspire creativity and attract success. While Zircon has sometimes been confused with cubic zirconia (a synthetic diamond simulant), natural Zircon is a distinct and valuable gemstone with its own set of symbolic meanings.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of these birthstones, given their differing physical properties.
Turquoise, due to its porosity and moderate hardness, requires gentle handling. It should be protected from chemicals, perfumes, lotions, and prolonged exposure to water, which can cause discoloration or damage to the matrix. Cleaning should be done with a soft, dry cloth. Avoid ultrasonic cleaners and steam cleaning. For stabilized Turquoise, a slightly damp cloth can be used, but the stone must be dried immediately.
Tanzanite can be cleaned with warm, soapy water and a soft brush. It is important to avoid sudden temperature changes and harsh chemicals. While it is relatively durable, it should be stored separately from harder gemstones to prevent scratching. Ultrasonic cleaners are not recommended, as the vibrations could potentially damage the stone, especially if it has any inclusions or fractures.
Zircon is one of the more durable gemstones among the three, with good hardness and toughness. It can be cleaned safely with warm soapy water and a soft brush. Ultrasonic cleaners are generally safe for Zircon, but it is advisable to avoid them if the stone has any inclusions or if it has been treated (though heat treatment is stable). As with all gemstones, it is best to store Zircon jewelry separately to prevent scratching by other harder materials.
Conclusion
The December birthstones—Turquoise, Tanzanite, and Zircon—offer a remarkable diversity in color, history, and character. From the ancient, protective talisman of Turquoise, with its millennia-long legacy, to the vibrant, transformative energy of the modern Tanzanite, and the brilliant, fiery sparkle of Zircon, each stone provides a unique connection to the natural world and human culture. Their geological origins span the globe, from the arid mines of the American Southwest and the exclusive hills of Tanzania to the ancient alluvial deposits worldwide. For those born in December, these gemstones are more than mere adornments; they are carriers of history, symbols of personal meaning, and timeless treasures that reflect the beauty and complexity of the earth itself. Whether chosen for their aesthetic appeal, historical significance, or metaphysical properties, Turquoise, Tanzanite, and Zircon remain enduring and cherished symbols of the twelfth month.