The month of December is uniquely distinguished in the world of gemstones, not by a single definitive stone, but by a vibrant palette of blue and violet gems. While many months are assigned a single birthstone, December offers a diverse selection, allowing those born in this winter month a choice of color, value, and personal significance. The primary stones celebrated today are tanzanite, turquoise, zircon, and topaz, each possessing a unique geological origin, a rich history, and distinct gemological characteristics. This comprehensive guide delves into the science, lore, and beauty of these remarkable gems.
A Rich Tapestry of Choice: The December Birthstones
Unlike months with a singular gem, December's identity is defined by variety. The most commonly cited birthstones for the month are tanzanite, turquoise, blue zircon, and blue topaz. This multiplicity offers a wide spectrum of choices, from the iconic, sky-blue hues of turquoise to the deep, violet-blue of tanzanite and the fiery brilliance of zircon.
The modern list of birthstones, standardized by organizations like the American National Retail Jewelers Association in the early 20th century, has evolved over time. December's list has seen more additions than most, reflecting both the discovery of new gems and a desire to provide consumers with more options. Turquoise and zircon represent the traditional, historical birthstones, while tanzanite and blue topaz are more modern additions that have gained immense popularity for their vibrant colors and availability in the jewelry market. This guide will explore each of these gems in detail, providing an expert perspective on their place in both history and modern adornment.
Tanzanite: The Gem of a Single Source
Among the most significant gemstone discoveries of the 20th century, tanzanite is a relative newcomer to the world of fine jewelry. This stunning bluish-purple stone is prized for its unique coloration and remarkable clarity.
Discovery and Geological Origin
Tanzanite was first discovered in the 1960s. It is a variety of the mineral zoisite and is found in only one location on Earth: a tiny, four-by-one-and-a-half-mile mining area in the Simanjiro District of the Manyara Region in Tanzania. This incredibly small geographical footprint has led to tanzanite being described as a "truly finite mineral," a gemstone of extreme rarity whose supply is limited to this single source. Initially, the stone was known as "blue zoisite," but in a strategic move to associate it with its country of origin and enhance its market appeal, the name was changed to tanzanite.
Gemological Properties and Color
Tanzanite is celebrated for its pleochroism—the ability to display different colors when viewed from different crystal directions. A single stone can show shades of blue, violet, and burgundy simultaneously. The most desirable color is a deep, saturated violet-blue. Most tanzanite available on the market has been heat-treated to achieve its stable and uniform blue-violet color; this treatment is widely accepted in the trade and removes any yellow or brownish tints from the raw zoisite.
Symbolism and Lore
As a modern gem, tanzanite's lore is less ancient than that of its counterparts, but no less potent. It is often associated with a unique meaning of clarity, transformation, and spiritual awakening. Its discovery in the 20th century has allowed it to be embraced by a new generation, and it is frequently chosen for its contemporary elegance and rarity.
Turquoise: An Ancient Stone of Protection and Luck
Turquoise is perhaps the most historically significant of December's birthstones, with a legacy that spans millennia and continents. Its iconic blue-green hue has been cherished by countless cultures for its beauty and perceived metaphysical powers.
History and Cultural Significance
The name "turquoise" itself reveals an early trade route; it is derived from the French pierre turquoise, meaning "Turkish stone," as the gem was brought to Europe from Turkey. However, its origins lie much farther east, in Persia (modern-day Iran), where it was mined for thousands of years. Ancient Egyptians adorned themselves with turquoise, mining it in the Sinai Peninsula, and it was a sacred stone in many Native American cultures, particularly among the Navajo, Zuni, and Pueblo peoples of the American Southwest. For these cultures, turquoise was a symbol of the sky and water and was believed to offer protection, good fortune, and healing.
Gemological Properties and Identification
Turquoise is an opaque mineral with a waxy to vitreous luster. Its chemical formula is a hydrated phosphate of copper and aluminum, which is responsible for its characteristic blue and green colors. The presence of copper yields a blue color, while iron and other impurities can shift it toward green. A key identifying feature of natural turquoise is the presence of a "matrix"—a fine, web-like pattern of darker host rock (often iron pyrite or sandstone) that remains within the turquoise stone. Turquoise is relatively soft, with a Mohs hardness of 5 to 6, making it susceptible to scratches and chemicals.
Symbolism and Metaphysical Beliefs
Turquoise is universally regarded as a stone of protection, tranquility, and good fortune. It is believed to calm the mind, reduce stress, and bring inner peace. Its lore is rich and varied, from being used as a talisman against the "evil eye" in ancient Persia to being considered a sacred stone by Native American warriors and healers. It remains one of the most beloved gemstones for amulets and spiritual jewelry.
Zircon: The Diamond Imitator with Ancient Roots
Often confused with the synthetic cubic zirconia, natural zircon is one of the oldest minerals on Earth and a traditional December birthstone with exceptional brilliance and fire.
Historical Significance and Lore
Zircon has been used in jewelry for centuries, with blue zircon being particularly popular during the Victorian era. Its name is thought to be derived from the Persian word zargun, meaning "gold-colored," though zircon occurs in a variety of colors. As a gemstone, it is believed to promote honor, purity, and wisdom. It was traditionally worn as a protective amulet, said to ward off evil spirits and promote restful sleep.
Gemological Properties
Zircon is a natural gemstone that should not be confused with synthetic cubic zirconia (CZ), a diamond simulant. Zircon is a heavy stone with a high refractive index, giving it exceptional brilliance and fire that can rival that of a diamond. It is also doubly refractive, meaning light splits into two rays as it passes through the crystal. Zircon comes in a range of colors, but the most popular for jewelry is the heat-treated blue variety, which displays a brilliant, icy blue. It is relatively hard, with a Mohs hardness of 7.5, but it can be brittle due to its crystal structure.
Sources
While zircon is found in many locations worldwide, including Australia, Sri Lanka, and Thailand, the sources do not provide specific modern mining locations for the blue variety used in birthstone jewelry.
Blue Topaz: A Modern Favorite with Sky-Blue Hues
While topaz in its natural state can be many colors, the sky-blue and deep "Swiss blue" varieties have become a staple of the modern jewelry industry, especially as a December birthstone.
Geological Formation and Sources
Topaz is a silicate mineral that forms in igneous rocks, particularly in pegmatites and vapor-rich cavities in rhyolite lava. It is found in various locations around the world. While the provided sources do not specify mining locations for blue topaz, they highlight its popularity and aesthetic appeal.
Gemological Properties and Treatments
Natural topaz is often colorless, and the vibrant blue shades seen in jewelry are typically the result of irradiation and heat treatment. This process is stable and permanent. Topaz has a Mohs hardness of 8, making it a durable and excellent choice for all types of jewelry, including rings. It is important to note that blue topaz is distinct from the naturally blue topaz found in ancient times, which was much rarer.
Symbolism and Lore
Blue topaz is associated with calm, serenity, and clarity. Its cool, sky-blue color is said to promote communication and emotional balance. It is a stone of peaceful energy, making it a popular choice for those seeking tranquility and inspiration.
Care and Maintenance of December's Birthstones
Given the diverse physical properties of December's birthstones, proper care is essential to maintain their beauty and longevity. A one-size-fits-all approach is not suitable for this group of gems.
High-Maintenance Gems: Turquoise and Tanzanite
- Turquoise: Due to its relatively low hardness (5-6) and porous nature, turquoise is susceptible to damage. It should be protected from chemicals, including perfumes, lotions, and household cleaners, which can cause discoloration. Clean turquoise jewelry with warm, soapy water and a soft cloth. Avoid ultrasonic cleaners and steam cleaners.
- Tanzanite: With a Mohs hardness of 6.5 to 7, tanzanite is softer than many other faceted gemstones. It also has perfect cleavage in one direction, meaning it can split if struck with force. This makes it a less-than-ideal choice for rings that will be worn daily. It is best suited for pendants and earrings. Clean with warm, soapy water and a soft brush; avoid ultrasonic and steam cleaners.
Durable Gems: Zircon and Blue Topaz
- Zircon: While fairly hard (7.5 to 8), zircon is brittle and can be easily chipped if knocked against a hard surface. It is best set in protective settings and handled with care. Clean with warm, soapy water and a soft brush. Avoid ultrasonic cleaners, as the vibrations can cause existing chips to worsen.
- Blue Topaz: As a harder gem (8 on the Mohs scale), blue topaz is quite durable and suitable for everyday wear. It is, however, susceptible to fracturing from sharp blows. Standard jewelry cleaning is safe: warm, soapy water with a soft brush. Avoid extreme temperature changes and harsh chemicals.
Conclusion
The birthstones of December offer a remarkable journey through gemology, history, and personal expression. From the singular, rare beauty of tanzanite to the ancient protective power of turquoise, the brilliant fire of zircon, and the serene calm of blue topaz, there is a gem to suit every preference. These stones are more than just beautiful adornments; they are a connection to the Earth's geological wonders and a rich tapestry of human culture. For those born in the final month of the year, the choice of a birthstone is a celebration of a unique and vibrant heritage, offering a piece of the sky, the sea, and the ancient earth itself.