December, the final month of the calendar year, is uniquely celebrated with not one, but three recognized birthstones: turquoise, tanzanite, and blue zircon. These gemstones, each possessing distinct origins, properties, and historical significance, offer a diverse palette of color and symbolism for those born in this month. While ruby historically held association with December, the modern tradition favors these vibrant blue and blue-green stones, reflecting a rich evolution in birthstone lore. This article will delve into the history, geological origins, gemological characteristics, and cultural significance of these three December birthstones.
A History of December’s Gemstones
The designation of birthstones has evolved considerably over time. Early traditions, inspired by Biblical texts, initially linked ruby to December. However, by the 19th century, turquoise began to emerge as a prominent December birthstone, popularized by Tiffany & Co.’s “Gregorian Birthstone Poems” pamphlet in 1870. The National Association of Jewellers further solidified turquoise’s position in 1912, listing it as the primary December stone with lapis lazuli as an alternative.
The 20th and 21st centuries witnessed the addition of zircon and, more recently, tanzanite to the December birthstone family. Zircon was added to the list in 1952, and tanzanite gained recognition in 2002. This expansion reflects both evolving gemological discoveries and changing consumer preferences. The inclusion of multiple birthstones for a single month allows for greater choice and personalization, catering to diverse tastes and budgets. The question of the “real” birthstone for December remains open to interpretation, as each gem boasts its own unique history and appeal.
Turquoise: A Stone of Protection and Healing
Turquoise, a semi-translucent gem composed of copper and aluminum phosphate, is perhaps the most consistently recognized December birthstone. Its distinctive blue-green hue is formed through a chemical interaction between acidic groundwater and minerals containing aluminum and phosphorus. Mined in areas where these conditions are met, turquoise has been valued for millennia.
Historically, turquoise has been revered for its perceived healing properties and protective qualities. In India, it is associated with Sagittarius and believed to promote good health. Traditional Hindu practices often involve wearing birthstone rings set to ensure direct skin contact with the gem. Beyond India, turquoise has held significance in various cultures, often symbolizing prosperity, good fortune, and spiritual grounding.
Tanzanite: A Modern Marvel from Tanzania
Tanzanite, a relatively recent addition to the birthstone family, was discovered in the 1960s near Mount Kilimanjaro in Tanzania. Uniquely, tanzanite is found nowhere else on Earth, making it a geographically exclusive gemstone. Marketed by Tiffany & Co., it quickly gained popularity for its captivating blue to purple coloration, rivaling the finest sapphires in intensity.
The gem exhibits strong pleochroism, displaying different colors when viewed from different angles and under varying lighting conditions. This characteristic results in a captivating interplay of purple and blue hues within a single stone. Like blue zircon, tanzanite is commonly heat-treated to enhance its coloration, bringing out its most attractive shades.
Blue Zircon: Brilliance and Ancient Origins
Blue zircon, a natural gem often mistaken for cubic zirconia, is another traditional December birthstone. Mined primarily in Thailand, Cambodia, and Vietnam, zircon occurs in a variety of colors. The blue variety is often achieved through heat treatment, resulting in a lovely pastel shade.
Zircon is renowned for its high refractive index, contributing to its exceptional brilliance. For centuries, colorless zircon has been used as a diamond substitute due to its similar optical properties. However, zircon’s significance extends beyond its aesthetic appeal. It contains trace amounts of uranium and thorium, making it invaluable in radiometric dating. Some zircon specimens have been calculated to be as old as 4.4 billion years, representing the oldest minerals ever recorded on Earth.
Gemological Properties: A Comparative Overview
The three December birthstones exhibit distinct gemological properties, influencing their durability, appearance, and value.
| Property | Turquoise | Tanzanite | Blue Zircon |
|---|---|---|---|
| Chemical Formula | CuAl₆(PO₄)₄(OH)₈·4H₂O | Ca₂Al₃(SiO₄)₃(OH) | ZrSiO₄ |
| Color | Blue-Green | Blue to Purple | Blue |
| Mohs Hardness | 5-6 | 6-7 | 6.5-7.5 |
| Refractive Index | 1.61 - 1.62 | 1.48 - 1.50 | 1.81 - 2.02 |
| Transparency | Translucent | Transparent | Transparent |
The Mohs hardness scale indicates a gemstone’s resistance to scratching. Turquoise, with a hardness of 5-6, is the softest of the three, requiring careful handling to avoid damage. Tanzanite (6-7) and blue zircon (6.5-7.5) are more durable, but still susceptible to scratches and chipping. Zircon’s high refractive index contributes to its exceptional brilliance, while tanzanite’s pleochroism creates a unique visual effect.
Symbolism and Metaphysical Beliefs
Each December birthstone carries its own set of symbolic meanings and metaphysical beliefs. Turquoise is often associated with protection, healing, and good fortune. Tanzanite is believed to promote spiritual awareness, intuition, and transformation. Blue zircon is thought to enhance clarity, wisdom, and emotional balance.
These beliefs, rooted in ancient traditions and cultural lore, add another layer of significance to these gemstones. While not scientifically proven, the perceived metaphysical properties contribute to their enduring appeal and personal meaning for those who wear them.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of December birthstones. Turquoise, being relatively soft, should be protected from scratches and harsh chemicals. Cleaning can be done with a soft cloth and mild soapy water. Tanzanite and blue zircon require similar care, avoiding ultrasonic cleaners and harsh chemicals. Due to the potential for heat treatment affecting color, avoid prolonged exposure to direct sunlight or heat. Regular cleaning with a soft brush and mild soapy water will help preserve their brilliance.
Conclusion
The December birthstones – turquoise, tanzanite, and blue zircon – represent a captivating blend of history, geology, and symbolism. From the ancient protective qualities of turquoise to the modern allure of tanzanite and the enduring brilliance of blue zircon, these gemstones offer a diverse range of options for those born in the final month of the year. Their unique properties and captivating beauty continue to inspire and enchant, solidifying their place as cherished symbols of December.