December is a unique month in the world of birthstones, distinguished by a quartet of beautiful blue gemstones: turquoise, tanzanite, zircon, and blue topaz. Unlike months traditionally associated with a single gem, December offers a spectrum of choices, each with its own history, symbolism, and appeal. This article will explore the origins, properties, and significance of these four December birthstones, providing a comprehensive overview for enthusiasts, buyers, and students of gemology.
History and Lore
The tradition of associating gemstones with specific months has evolved over time. Early birthstone lists, inspired by Biblical texts, initially designated ruby as the stone for December. However, the modern list has undergone several revisions. By 1870, turquoise was recognized as a December birthstone by Tiffany & Co. in their “Gregorian Birthstone Poems” pamphlet. The National Association of Jewellers later added lapis lazuli as an alternative in 1912. Zircon was incorporated into the list in 1952 by the Jewelry Industry Council of America, and tanzanite was the most recent addition in 2002.
This evolution reflects changing preferences, discoveries of new gemstones, and the influence of gemological societies and jewelry retailers. While turquoise has the most consistent historical association with December, each of the four stones holds its own place in lore and tradition. Turquoise, for example, has been revered for centuries, while tanzanite is a relatively recent discovery, unearthed in Tanzania in 1967.
Geological Formation and Sources
The origins of these December birthstones are geographically diverse. Turquoise is formed in relatively shallow deposits as a secondary mineral, produced by weathering of copper-rich rocks. It is found in arid regions, often associated with copper deposits. Historically, Persia (now Iran) was a significant source of high-quality turquoise, and the stone was brought to Europe via the Silk Road. Today, significant deposits are also found in the United States, particularly in Arizona, Nevada, and New Mexico.
Zircon is a zirconium silicate mineral that forms in igneous rocks, metamorphic rocks, and sedimentary deposits. Blue zircon is a color variety created by heat treatment. It is found in various locations worldwide, including Sri Lanka, Cambodia, Myanmar, and Australia.
Tanzanite, a relatively recent discovery, is found exclusively in the Merelani Hills of northern Tanzania, near Mount Kilimanjaro. It is a trichroic gemstone, meaning it displays three different colors – blue, violet, and burgundy – depending on the viewing angle. Its formation requires specific geological conditions, making it exceptionally rare.
Blue topaz is a variety of topaz that has been irradiated and heated to produce its vibrant blue color. Topaz itself forms in igneous and metamorphic rocks, often in pegmatites. Major sources of topaz include Brazil, Nigeria, and Russia.
Gemological Properties
Each of the December birthstones possesses unique gemological properties.
Turquoise: This opaque gemstone typically ranges in color from sky blue to greenish-blue, often with matrix (veins of other minerals) present. Its hardness on the Mohs scale is relatively low, ranging from 5 to 6, making it susceptible to scratching.
Zircon: Blue zircon exhibits strong brilliance and a high refractive index. Its hardness is 6.5 to 7.5 on the Mohs scale, making it more durable than turquoise but still requiring careful handling.
Tanzanite: This gemstone displays a pleochroic effect, showing different colors depending on the viewing angle. Its hardness is 6 to 7 on the Mohs scale. Tanzanite is also sensitive to heat and can be damaged by prolonged exposure to sunlight.
Blue Topaz: Blue topaz is a relatively hard gemstone, with a Mohs hardness of 8. This makes it durable and suitable for everyday wear. It exhibits excellent brilliance and clarity.
The following table summarizes key properties:
| Gemstone | Chemical Formula | Hardness (Mohs) | Color(s) | Transparency |
|---|---|---|---|---|
| Turquoise | CuAl6(PO4)4(OH)8·4H2O | 5-6 | Sky blue, greenish-blue | Opaque |
| Zircon | ZrSiO4 | 6.5-7.5 | Blue | Transparent |
| Tanzanite | Ca2Al3(SiO4)3(OH) | 6-7 | Blue, violet, burgundy | Transparent |
| Blue Topaz | Al2SiO4(OH,F)2 | 8 | Blue | Transparent |
Symbolism and Metaphysical Beliefs
Throughout history, each of these gemstones has been attributed with specific meanings and powers. Turquoise has long been considered a protective stone, believed to ward off negative energy and bring good fortune. It is also associated with self-expression and compassion.
Zircon is thought to enhance mental clarity, intuition, and grounding. It is believed to promote wisdom and prosperity.
Tanzanite is associated with transformation, spiritual growth, and intuition. It is said to connect the wearer to higher consciousness and facilitate communication.
Blue topaz is believed to promote calmness, communication, and emotional balance. It is often used to soothe the mind and encourage self-expression.
Care and Cleaning
Proper care is essential to maintain the beauty of these December birthstones. Turquoise, due to its relative softness, should be protected from scratches and impacts. It is best cleaned with a soft cloth and mild soap and water. Avoid harsh chemicals and ultrasonic cleaners.
Zircon and blue topaz are more durable but should still be handled with care. They can be cleaned with warm soapy water and a soft brush. Avoid ultrasonic cleaners, as they may damage the stones.
Tanzanite is sensitive to heat and should not be exposed to prolonged sunlight or sudden temperature changes. It is best cleaned with a soft cloth and mild soap and water. Avoid ultrasonic cleaners and steam cleaners.
December Birthstone by Day
While all four gemstones are associated with December, some sources suggest specific stones for each day of the month. According to one such listing, blue topaz, tanzanite, turquoise, and blue zircon rotate as the birthstone for each day of December.
Conclusion
December’s birthstones – turquoise, tanzanite, zircon, and blue topaz – represent a diverse and captivating collection of gemstones. From the ancient protective powers of turquoise to the modern allure of tanzanite, each stone offers a unique blend of history, beauty, and symbolism. Whether chosen for their aesthetic appeal, metaphysical properties, or personal significance, these gemstones embody the spirit of December and provide a meaningful connection to the month of their birth. Their versatility allows them to be incorporated into a wide range of jewelry styles, making them cherished gifts and enduring treasures for generations to come.