December boasts a unique distinction among the months: it possesses not one, but three officially recognized birthstones – Turquoise, Tanzanite, and Blue Zircon. While Turquoise holds the longest-standing tradition as the December gem, Tanzanite and Blue Zircon were added in 2002, offering a spectrum of blue hues and rich histories for those born in the final month of the year. This article will explore the geological origins, historical significance, gemological properties, and cultural lore surrounding these captivating gemstones.
A History Rooted in Antiquity: Turquoise
Turquoise is arguably the most ancient of the December birthstones, with evidence of its use dating back over 5,500 years. A bracelet crafted from turquoise, discovered in Egypt, is among the oldest known pieces of jewelry. Ancient Egyptians, referring to the gem as mefkat meaning “joy,” mined turquoise extensively from the Sinai Peninsula as early as 3000 BC. They valued it not only for its aesthetic appeal but also for its protective qualities, associating it with the sky and motherhood goddess Hathor.
The gem’s reverence extended beyond Egypt. Ancient Persians called it pērōzah, meaning “victory,” believing it to be a heavenly stone. It was incorporated into turbans, weaponry, and the decoration of mosques. Across the Mediterranean, ancient Greeks and Romans knew turquoise as callais, crafting it into beads, necklaces, and rings. In the Americas, particularly among Aztec cultures, turquoise held sacred status, believed to be a gift from the deity Quetzalcoatl. Rulers were buried with turquoise in their mouths, signifying its importance in both life and the afterlife. Native American tribes similarly prized turquoise for ceremonial purposes, as talismans, and even as a form of currency, with the Apache believing it enhanced the accuracy of their bows.
The Recent Addition: Tanzanite
In contrast to Turquoise’s millennia-spanning history, Tanzanite is a relatively recent discovery. Added to the list of December birthstones in 2002, this gem quickly gained popularity for its striking violet-blue coloration. Tanzanite is found in a very limited geographical area: the Merelani Hills of northern Tanzania, hence its name. Its discovery in 1967 is attributed to Maasai tribesmen, though its gemological significance wasn’t immediately recognized.
The gem’s appeal was significantly boosted by Tiffany & Co., who named it and launched a marketing campaign that highlighted its beauty and rarity. Celebrity endorsements, including sightings on Anne Hathaway, Cate Blanchett, and Sarah Jessica Parker, as well as a notable gift from Jay-Z to Beyoncé, further cemented Tanzanite’s status as a desirable gemstone.
A Long-Forgotten Gem: Blue Zircon
Blue Zircon also joined the ranks of December birthstones in 2002, though its history as a gem material extends much further back. Zircon was added to the 1912 list of birthstones, but later fell out of favor. It is important to note that Zircon should not be confused with cubic zirconia, a synthetic diamond simulant. Zircon is a naturally occurring mineral, and while colorless varieties exist, the blue hues are particularly prized as birthstones.
Geological Origins and Sources
Turquoise forms in relatively dry, arid regions, typically in the vicinity of copper deposits. It is a hydrated phosphate of copper and aluminum, forming in fissures and cavities within rocks. Significant sources include the southwestern United States (Arizona, New Mexico, Nevada), Iran, Egypt, and the Sinai Peninsula.
Tanzanite, a variety of the mineral zoisite, is formed through complex geological processes involving intense heat and pressure. Its unique blue to violet color is achieved through heat treatment of brownish zoisite. As previously mentioned, its sole known commercial source is the Merelani Hills in Tanzania.
Blue Zircon is found in a variety of geological settings, including igneous and metamorphic rocks. Major sources include Cambodia, Sri Lanka, and Myanmar. The blue color in zircon is often achieved through heat treatment of brownish or greenish zircon crystals.
Gemological Properties
The three December birthstones exhibit distinct gemological properties:
| Property | Turquoise | Tanzanite | Blue Zircon |
|---|---|---|---|
| Chemical Formula | CuAl6(PO4)4(OH)8·4H2O | Ca2Al3(SiO4)3(OH) | ZrSiO4 |
| Color | Blue to Green | Blue to Violet | Blue |
| Hardness (Mohs) | 5-6 | 6-7 | 6.5-7.5 |
| Crystal System | Triclinic | Orthorhombic | Tetragonal |
| Refractive Index | 1.61 - 1.62 | 1.48 - 1.50 | 1.81 - 2.02 |
Turquoise, with a hardness of 5-6 on the Mohs scale, is relatively soft and porous, making it susceptible to damage from impacts and chemicals. Tanzanite, ranging from 6 to 7 on the Mohs scale, is more durable but can still be cleaved or cracked by sudden temperature changes. Blue Zircon, with a hardness of 6.5-7.5, is relatively durable, though it exhibits strong double refraction, which can affect its appearance.
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 prosperity. It was believed to ward off evil spirits and promote healing.
Tanzanite is often linked to transformation, intuition, and spiritual awareness. It is said to facilitate communication and encourage self-expression.
Blue Zircon is believed to promote wisdom, honor, and prosperity. Historically, it was thought to protect travelers and bring good dreams.
Care and Cleaning
Due to their varying hardness and sensitivities, each December birthstone requires specific care. Turquoise, being porous, should be cleaned with a soft cloth and mild soapy water. Avoid harsh chemicals, ultrasonic cleaners, and prolonged exposure to sunlight. Tanzanite is best cleaned with warm, soapy water and should never be subjected to ultrasonic or steam cleaning, as the heat can damage the stone. Blue Zircon can be cleaned with warm, soapy water, but caution should be exercised due to its potential for cleavage.
Conclusion
The December birthstones – Turquoise, Tanzanite, and Blue Zircon – represent a captivating blend of ancient tradition and modern discovery. From the millennia-old history of Turquoise to the recent emergence of Tanzanite and the rediscovered beauty of Blue Zircon, these gemstones offer a diverse range of colors, properties, and symbolic meanings. Whether chosen for their aesthetic appeal, historical significance, or perceived metaphysical benefits, these blue gems provide a beautiful and meaningful connection to the month of December.