December 13th is a unique date in the gemological calendar, marked not by a single birthstone but by a distinguished trio: Tanzanite, Turquoise, and Zircon. This convergence of three distinct gemstones offers a rich palette of blue hues, from the deep violet-blue of Tanzanite to the robin's egg sky of Turquoise and the vibrant sparkle of Blue Zircon. Each stone carries its own profound history, geological origin, and cultural significance, making December 13th a celebration of diversity in both color and lore. For enthusiasts, collectors, and those born on this day, understanding the individual characteristics of these gems provides a deeper appreciation for their collective beauty and symbolism.
The selection of these three stones reflects a blend of ancient tradition and modern discovery. Turquoise, with its millennia-old legacy, stands as a testament to human fascination with opaque, sky-colored minerals. Zircon, one of the oldest minerals on Earth, offers brilliant fire and a complex history often confused with synthetic cubic zirconia. Tanzanite, the youngest of the trio, represents a geological marvel discovered in the 20th century, prized for its unique trichroic color. This article explores the history, formation, properties, and care of each December 13th birthstone, drawing exclusively from established gemological sources to provide an authoritative guide for the discerning reader.
History and Lore: A Journey Through Time
The historical narratives of the December 13th birthstones span continents and millennia, each stone embedding itself in the cultural fabric of different civilizations.
Turquoise: The Ancient Talisman Turquoise is arguably the most historically significant of the three, with evidence of its use dating back over 7,000 years. It is believed to be the world’s oldest gem material, with archaeological finds in burial sites in western Iran dating to approximately 7000 BCE. The stone was cherished by ancient Egyptians, who called it "mefkat," meaning "joy" and "delight." They mined it in the Sinai region around 5500 BCE and adorned pharaohs and rulers with it. Chinese artisans carved turquoise more than 3,000 years ago, and it has been found in the tombs of ancient Egypt, underscoring its universal appeal.
The name "turquoise" originates from the French expression "pierre tourques," or "Turkish stone," from the 13th century, reflecting its trade route through Turkey. Its metaphysical lore is extensive. From the 13th century onward, it was believed to protect the wearer from falls, particularly from horses, and was often set on horse bridles. A superstition held that the stone would break into several pieces when disaster was imminent. Hindu mystics believed that seeing a turquoise after beholding the new moon ensured fantastic wealth. For Native American tribes, particularly the Apache, turquoise held spiritual significance; they believed it could be found by following a rainbow to its end. It was associated with promoting good health, fortune, happiness, peace, and protection.
Zircon: The Mistaken Gem and Symbol of Wisdom Zircon’s history is marked by both admiration and confusion. It is one of the oldest minerals on Earth, and its brilliance has been prized across many cultures. However, it has frequently been mistaken for more expensive gems like diamond or, more recently, confused with synthetic cubic zirconia (which is not a natural mineral). This historical confusion has sometimes obscured its true value. Zircon has been admired for its clarity and fire, and it has often been used as a diamond simulant. Its diverse color palette, including the blue variety associated with December, has contributed to its long-standing presence in jewelry and lore. While specific ancient attributions for blue zircon are not detailed in the provided sources, its general history as a gemstone of brilliance and clarity is noted, linking it to success and transformation.
Tanzanite: The Modern Marvel In stark contrast to its ancient counterparts, Tanzanite is a gemstone of the modern era. It was discovered only in 1967, making it the youngest of the December 13th birthstones. It is found exclusively in a single, small area in Tanzania, which gives it its name. Its discovery is a significant event in the 20th-century gemological world, and its rapid rise to prominence is a testament to its unique beauty. Tanzanite is prized for its deep blue to bluish-purple color, which can range from ultramarine to lavender. Its lore is less ancient but is tied to themes of transformation and new beginnings, aligning with its recent geological formation and discovery.
The Path to Modern Birthstone Status The formalization of these stones as birthstones for December is a more recent development. Turquoise was officially named a December birthstone in 1912 by the American National Association of Jewelers (now the Jewelers of America). This list was created to standardize birthstones for the jewelry trade. Blue Topaz, while not one of the three primary December 13th stones mentioned in the core sources for this date, is often cited as a modern alternative for the month of December in the United States, particularly for its sky-blue color. However, for the specific date of December 13th, the established trio remains Tanzanite, Turquoise, and Zircon.
Geological Formation and Sources
The origins of these gemstones are as diverse as their histories, ranging from ancient mineral formations to recent geological events.
Turquoise: An Hydrous Phosphate Mineral Turquoise is a hydrous phosphate of copper and aluminum, forming in arid regions where acidic, copper-rich groundwater interacts with aluminum-bearing rocks. Its color, ranging from blue to green, is derived from copper (blue) and iron (green). The presence of zinc can impart a yellowish hue. Turquoise is typically found in massive form, often with veins or spiderwebs of matrix (the host rock) running through it. Major sources include Iran, China, Mexico, the Middle East, Kazakhstan, and the United States. Notably, the most sought-after color, often called "Robin's Egg Blue" or "Persian Blue," historically came from Iran. The stone is semi-translucent to opaque and is often stabilized with wax or dye to enhance its durability and color.
Zircon: A Zirconium Silicate Mineral Zircon (ZrSiO₄) is a zirconium silicate mineral that forms in igneous and metamorphic rocks. It is one of the hardest minerals and is highly resistant to weathering, which is why it is often found in sedimentary deposits. Blue zircon is typically produced by heat-treating brown zircon crystals. This heat treatment can produce a vivid blue color, which is the most popular for jewelry. Zircon is found in many locations worldwide, including Cambodia, Sri Lanka, Thailand, and Australia. Its high refractive index and strong dispersion (fire) give it exceptional brilliance, often rivaling that of diamond.
Tanzanite: A Unique Variety of Zoisite Tanzanite is a blue/purple variety of the mineral zoisite. Its formation is unique and geologically specific. It is found only in the Merelani Hills of Northern Tanzania, near Mount Kilimanjaro. The gemstone is formed by the intense heat and pressure from tectonic plate activity that occurred about 585 million years ago. This specific geological event created the conditions for the formation of zoisite crystals containing vanadium, which gives Tanzanite its distinctive color. The mining area is remarkably small, estimated to be only a few square kilometers, making it one of the most exclusive gemstone sources in the world. Tanzanite is often found in its raw, brownish form and requires heat treatment to achieve its signature blue to violet-blue color.
Gemological Properties
Understanding the physical and optical properties of these stones is crucial for identification, valuation, and care. The following table summarizes key gemological data for Tanzanite, Turquoise, and Zircon, based on the provided sources.
| Property | Tanzanite | Turquoise | Zircon (Blue) |
|---|---|---|---|
| Mineral Species | Zoisite | Hydrous Copper Aluminum Phosphate | Zircon |
| Chemical Formula | Ca₂Al₃(SiO₄)₃(OH) | CuAl₆(PO₄)₄(OH)₈·4H₂O | ZrSiO₄ |
| Color Range | Blue to bluish-purple | Blue to green, with matrix veins | Colorless to blue, yellow, brown, red |
| Hardness (Mohs) | 6.5 - 7 | 5 - 6 | 6.5 - 7.5 |
| Transparency | Transparent to translucent | Semi-translucent to opaque | Transparent |
| Refractive Index | 1.690 - 1.700 | 1.610 - 1.650 | 1.92 - 2.01 |
| Special Properties | Trichroic (shows three colors) | Often contains matrix; color can change | High brilliance and fire (dispersion) |
| Heat Treatment | Common and accepted to enhance color | Not typically heat-treated (but often stabilized) | Common to achieve blue color from brown |
| Typical Sources | Tanzania (exclusively) | Iran, China, USA, Mexico, etc. | Cambodia, Sri Lanka, Australia, etc. |
Tanzanite Properties: Tanzanite is a relatively hard gemstone (6.5 - 7 on the Mohs scale), making it suitable for most jewelry, though it requires protection from hard blows. Its most remarkable optical property is trichroism—under different crystal directions, it can display three distinct colors: blue, violet, and burgundy. This characteristic is a key identifier. It has a refractive index ranging from 1.690 to 1.700.
Turquoise Properties: Turquoise is a softer stone, with a hardness of 5 to 6 on the Mohs scale. This makes it more susceptible to scratching and damage, requiring careful handling. Its opacity and typical inclusion of matrix (veins of the host rock) are defining features. The stone can be sensitive to chemicals, oils, and moisture, which can alter its color over time. Stabilization treatments are common to improve its durability and color stability.
Zircon Properties: Zircon is one of the hardest natural gemstones, with a hardness of 6.5 to 7.5, making it durable for jewelry. Its most striking feature is its high refractive index (1.92 - 2.01) and significant dispersion (0.039), which gives it exceptional brilliance and fire, often compared to diamond. Blue zircon, the variety associated with December, is almost always the result of heat treatment applied to brown zircon crystals. It is typically transparent and can be cut to maximize its sparkle.
Symbolism and Metaphysical Beliefs
The symbolic meanings attached to these gemstones are deeply rooted in cultural traditions and metaphysical practices.
Turquoise: Protection and Well-being As detailed in the sources, turquoise has been historically associated with a wide array of protective and beneficial powers. It was believed to ensure health, good fortune, and happiness. Specific lore includes protection from falls (especially from horses), acting as a warning stone by breaking when danger approached, and attracting wealth when seen after a new moon. For Native American cultures, it holds a sacred place, linked to spiritual beliefs and the natural world. Its color, reminiscent of the sky and water, is universally tied to tranquility, peace, and positive energy.
Zircon: Clarity and Success While the provided sources offer less specific metaphysical lore for blue zircon compared to turquoise, they note that zircon has been admired for its clarity and brilliance. Historically, it has been associated with wisdom, honor, and purity. Its fiery sparkle is often linked to success, prosperity, and spiritual transformation. As a December birthstone, it is believed to bring stability and clarity of thought to the wearer.
Tanzanite: Transformation and Intuition The modern symbolism of Tanzanite is often linked to its unique discovery and vibrant color. It is frequently associated with transformation, spiritual growth, and heightened intuition. Its trichroic nature, displaying different colors from different angles, is seen as a metaphor for seeing a situation from multiple perspectives. It is also linked to communication and a deeper connection with one's higher self. As a relatively new stone, its metaphysical properties are more contemporary but are embraced by many crystal healers and enthusiasts.
Care and Cleaning
Proper care is essential to preserve the beauty and integrity of each gemstone, given their distinct physical properties.
Caring for Tanzanite: With a hardness of 6.5 to 7, Tanzanite is durable enough for everyday wear but should be protected from sharp blows and extreme temperature changes, which can cause cleavage. It is best cleaned with warm, soapy water and a soft brush. Avoid ultrasonic cleaners and steam cleaning, as the vibrations and heat can damage the stone. Store it separately from harder gems like diamonds or sapphires to prevent scratching.
Caring for Turquoise: Due to its lower hardness (5-6) and porous nature, Turquoise requires the most careful handling. It should be protected from chemicals, cosmetics, perfumes, and even body oils, which can cause discoloration or degradation. Cleaning should be done gently with a soft, dry cloth. If necessary, use a mild soap and lukewarm water, but dry it thoroughly immediately. Avoid soaking the stone. Ultrasonic and steam cleaners are strictly forbidden. It is advisable to store turquoise jewelry in a soft cloth to prevent scratches from other items.
Caring for Zircon: Zircon's high hardness makes it relatively easy to care for. It can be cleaned with warm, soapy water and a soft brush. While it is generally stable, some zircon (especially blue varieties that have been heat-treated) can be sensitive to strong light over prolonged periods, though this is not a major concern for typical wear. It is safe to use an ultrasonic cleaner for zircon, but caution is advised if the stone has inclusions. As with all gemstones, avoid sudden temperature shocks.
Conclusion
The December 13th birthstones—Tanzanite, Turquoise, and Zircon—offer a captivating study in contrast: ancient versus modern, opaque versus transparent, and soft versus hard. Together, they provide a comprehensive palette of blue, satisfying a range of aesthetic and symbolic preferences. Turquoise stands as a timeless emblem of protection and well-being, its history woven into the fabric of ancient civilizations. Zircon dazzles with its diamond-like fire, a mineral of great age and enduring brilliance. Tanzanite, the geological infant, captivates with its exclusive origin and unique trichroic beauty.
For those born on December 13th, this trio represents a legacy of strength, clarity, and transformation. Whether chosen for its historical significance, its vibrant color, or its metaphysical properties, each stone carries a story that transcends its physical form. In the world of gemstones, they are not merely birthstones but artifacts of Earth's history and human culture, each worthy of admiration and careful preservation.