December boasts not one, but three recognized birthstones: tanzanite, turquoise, and zircon. Each of these gemstones offers a unique appeal, ranging from the vibrant blues and violets of tanzanite to the ancient mystique of turquoise and the fiery brilliance of zircon. This article will delve into the history, geological origins, gemological properties, and symbolism of these December birthstones, providing a comprehensive overview for enthusiasts and those seeking to learn more about these captivating gems.
A History Rooted in Tradition and Modern Discovery
The history of December’s birthstones is a blend of ancient tradition and relatively recent discovery. Turquoise holds the longest documented history, with evidence of its use dating back to 3000 BCE. Ancient Egyptians, Chinese artisans, and rulers throughout history prized turquoise for its sky-blue color and believed it offered protection and good fortune. From preventing falls from horses to foretelling disaster, turquoise was imbued with powerful protective qualities.
Zircon, mentioned in the Bible as jacinth or hyacinth, also boasts a long history, with some specimens containing uranium and thorium dating back 4.4 billion years – nearly as old as the Earth itself.
Tanzanite, however, is a modern addition to the birthstone family, discovered in Tanzania in 1967. Despite its recent discovery, it quickly gained popularity for its striking blue-violet hues and remains exclusively sourced from a small area within Tanzania, spanning just four square miles.
Geological Formation and Sources
The geological origins of these three birthstones are quite distinct. Turquoise is a semi-translucent to opaque gem formed in arid regions through a chemical reaction involving copper, aluminum, and other minerals. It often contains matrix, which are remnants of the host rock, giving each stone a unique pattern.
Zircon forms in igneous rocks and metamorphic rocks, often found alongside sapphire deposits in locations like Sri Lanka, Australia, Myanmar, Vietnam, and Cambodia. Its formation involves complex geological processes occurring deep within the Earth’s crust.
Tanzanite, a blue variety of the mineral zoisite, is formed through intense heat and pressure within the Merelani Hills of Tanzania. Its unique trichroism – displaying three separate colors (blue, violet, and red) depending on the viewing angle – is a result of its complex chemical composition and geological formation.
Gemological Properties: A Comparative Overview
Each December birthstone possesses unique gemological properties that contribute to its beauty and value.
Turquoise: This gem is not typically evaluated by the “Four Cs” (cut, clarity, color, carat) in the same way as diamonds. Its value is determined by color, with intense blue shades being the most prized. The presence of matrix can also enhance its appeal. Turquoise ranges from blue to green in color and is relatively soft, measuring between 5 and 6 on the Mohs scale of hardness.
Zircon: Zircon exhibits a hardness of 6 to 7.5 on the Mohs scale. It is known for its high refractive index, which gives it exceptional fire – the dispersion of light into rainbow colors. Zircon is commonly heat-treated to produce blue and colorless varieties, as well as orange, yellow, and red hues. Some zircons even display chatoyance, a cat’s-eye effect.
Tanzanite: Tanzanite registers between 6 and 7 on the Mohs scale of hardness. Its trichroism is a defining characteristic, displaying flashes of blue, violet, and red. Most tanzanite begins as brownish zoisite and undergoes heat treatment to reveal its vibrant blue to violet coloration, a process that permanently enhances its appearance.
The following table summarizes the key gemological properties:
| Gemstone | Chemical Formula | Hardness (Mohs) | Key Properties |
|---|---|---|---|
| Turquoise | CuAl6(PO4)4(OH)8·4H2O | 5-6 | Opaque, blue to green, often with matrix |
| Zircon | ZrSiO4 | 6-7.5 | High refractive index, fire, chatoyance |
| Tanzanite | Ca2Al3(SiO4)3(OH) | 6-7 | Trichroism (blue, violet, red) |
Symbolism and Metaphysical Beliefs
Throughout history, each of these birthstones has been associated with various symbolic meanings and metaphysical beliefs. Turquoise has long been considered a stone of protection, health, and good fortune. Ancient cultures believed it could ward off evil and guarantee well-being.
Zircon has been linked to prosperity and wisdom. Its ancient name, jacinth, was associated with nobility and spiritual insight.
Tanzanite, being a more recent discovery, has quickly become associated with transformation, intuition, and spiritual awakening. Its connection to Tanzania is also seen as a symbol of strength and resilience.
Care and Cleaning
Proper care is essential to maintain the beauty of these December birthstones. Zircon and tanzanite, with their moderate hardness, are susceptible to abrasion and should be protected from rough wear. Avoid wearing them during activities like gardening, sports, or dishwashing.
Turquoise, being relatively soft, requires gentle handling. Avoid harsh chemicals and ultrasonic cleaners, as they can damage the stone.
All three gemstones are best cleaned with warm, soapy water and a soft brush. Ultrasonic and steam cleaners are not recommended for tanzanite. Prolonged exposure to bright light can potentially alter the color of some heat-treated zircons, so storing them away from direct sunlight is advisable. Tanzanite can crack if exposed to very high temperatures or sudden temperature changes.
Conclusion
December’s birthstones – tanzanite, turquoise, and zircon – represent a fascinating blend of ancient tradition and modern discovery. Each gem offers a unique combination of beauty, history, and symbolism, making them cherished possessions for those born in the twelfth month of the year. From the protective energies of turquoise to the fiery brilliance of zircon and the transformative power of tanzanite, these gemstones continue to captivate and inspire.