December boasts a remarkable array of birthstones – tanzanite, turquoise, and zircon – each offering a unique shade of blue and a distinct history. While blue topaz is also frequently associated with December, the traditional and more historically significant gems are those discovered and cherished across millennia. This article will delve into the origins, properties, and symbolism of these captivating gemstones, providing a comprehensive overview for enthusiasts and those seeking to understand the rich heritage of December’s birthstones.
History and Lore
The longest-standing association with December lies with turquoise. Its history stretches back thousands of years, with evidence of its use by ancient civilizations in Egypt, China, and among indigenous cultures of the Americas. Ancient Egyptians adorned themselves with turquoise, believing it guaranteed health and good fortune. Chinese artisans carved the stone over 3,000 years ago, and it held significant cultural importance. From the 13th century onward, European cultures believed turquoise offered protection from falls, particularly while riding horses, and would even fracture to warn the wearer of impending disaster. Hindu traditions linked turquoise to wealth, believing that viewing the stone after a new moon would bring prosperity.
Zircon, while less steeped in ancient lore than turquoise, also has a long history. Its colorless variety served as a diamond substitute for centuries due to its high refractive index and brilliance. However, its significance extends beyond mere aesthetics; zircon contains trace amounts of uranium and thorium, making it crucial in the development of radiometric dating, with some specimens calculated to be as old as 4.4 billion years.
Tanzanite is the newcomer to the December birthstone family, discovered relatively recently in 1967 in Tanzania. Consequently, it lacks the extensive historical lore of turquoise and zircon. However, modern interpretations associate tanzanite with spiritual awakening and psychic abilities, believing it can activate the throat, third-eye, and crown chakras.
Geological Formation and Sources
Turquoise is a semi-translucent to opaque gem formed in relatively dry, arid regions. Its formation involves the interaction of copper-rich groundwater with aluminum and phosphorus-bearing rocks. The “matrix” – remnants of the host rock – often visible as veins running through turquoise, is a defining characteristic.
Zircon is found in a variety of geological settings, including igneous, metamorphic, and sedimentary rocks. It is mined primarily in Thailand, Cambodia, and Vietnam. The gem’s durability and resistance to weathering contribute to its presence in ancient alluvial deposits.
Tanzanite, uniquely, is found in only one location worldwide: Tanzania. This limited source contributes to its rarity and value. The gem forms within metamorphic rocks in the Merelani Hills of northern Tanzania.
Gemological Properties
The December birthstones exhibit a diverse range of gemological properties. Turquoise is not a crystalline gem; it’s a hydrated phosphate of copper and aluminum. Its color ranges from blue to green, with the most valuable shades being a vibrant “robin’s egg” blue with even distribution and minimal undertones. Turquoise is typically cut into cabochons, though it is also found as inlay, carvings, and beads. Its quality is graded on color, matrix, and texture, with dense textures exhibiting better polish luster.
Zircon boasts a high refractive index, contributing to its brilliance. It occurs in a wide spectrum of colors, including blue, green, yellow, red, and brown. Blue zircon is the most popular and often achieved through heat treatment. The gem’s chemical formula is ZrSiO₄. Radioactive elements within zircon can cause changes to its crystalline structure over time, a process known as metamictization. Zircon is categorized as “low zircon” (more altered, often cloudy) or “high zircon” (less altered, typically blue or colorless).
Tanzanite is a calcium aluminum silicate with the chemical formula Ca₂Al₃(SiO₄)₃(OH). It displays a captivating blue to bluish-purple hue. The most valuable tanzanite exhibits a vibrant, pure blue color, though purplish-blue and violet-blue shades are also highly sought after. Tanzanite is known for its strong pleochroism, meaning it displays different colors when viewed from different angles.
The following table summarizes key properties:
| Gemstone | Chemical Formula | Color(s) | Hardness (Mohs) | Typical Cut |
|---|---|---|---|---|
| Turquoise | CuAl₆(PO₄)₄(OH)₈·4H₂O | Blue to Green | 5-6 | Cabochon |
| Zircon | ZrSiO₄ | Blue, Green, Yellow, Red, Brown | 6.5-7.5 | Faceted |
| Tanzanite | Ca₂Al₃(SiO₄)₃(OH) | Blue, Bluish-Purple, Violet-Blue | 6-7 | Faceted |
Symbolism and Metaphysical Beliefs
Throughout history, each of these gemstones has been imbued with symbolic meaning. Turquoise has long been associated with protection, good fortune, and health. Its connection to horses and travel reflects a belief in its ability to safeguard journeys.
Zircon, beyond its scientific significance, is linked to prosperity and wisdom. The various colors of zircon are also believed to possess different properties, with blue zircon representing peace and tranquility.
Tanzanite, in modern metaphysical beliefs, is associated with transformation, healing, and psychic abilities. It is believed to facilitate communication with higher realms and activate the chakras.
Care and Cleaning
Due to their varying hardness levels, each birthstone requires specific care. Turquoise, being relatively soft (5-6 on the Mohs scale), is susceptible to scratches and damage from harsh chemicals. It should be cleaned with a soft cloth and mild soapy water. Avoid ultrasonic cleaners and steam cleaners.
Zircon, with a hardness of 6.5-7.5, is more durable than turquoise but can still be chipped or scratched. It can be cleaned with warm, soapy water and a soft brush.
Tanzanite, with a hardness of 6-7, requires gentle care. It is sensitive to heat and sudden temperature changes. Cleaning should be done with warm, soapy water and a soft cloth. Avoid ultrasonic cleaners and steam cleaners.
Conclusion
December’s birthstones – tanzanite, turquoise, and zircon – represent a captivating blend of history, geological wonder, and symbolic meaning. From the ancient lore surrounding turquoise to the recent discovery of tanzanite and the scientific significance of zircon, these gems offer a diverse range of options for those born in the twelfth month. Each stone possesses unique properties and a distinct beauty, making them cherished symbols of December and treasured additions to any gemstone collection.