The final month of the year is uniquely graced by not one, but three distinct and captivating birthstones: Turquoise, Zircon, and Tanzanite. Each gem offers a unique palette, history, and set of properties, providing a rich selection for those born in December. While Turquoise stands as the traditional cornerstone, celebrated for its vibrant color and protective lore, Zircon and Tanzanite have emerged as modern alternatives, each bringing its own scientific intrigue and aesthetic appeal. This article delves into the gemological characteristics, historical significance, and cultural symbolism of these three remarkable stones, drawing upon historical records and established gemological sources to provide a complete picture of December's birthstones.
The assignment of multiple stones to a single month reflects a long and complex evolution in the tradition of birthstones. This journey began with the twelve stones of the High Priest's breastplate described in the Book of Exodus and has been refined over centuries through cultural practices, astrological beliefs, and the commercial decisions of the early 20th century. For the December-born, this history culminates in a trio of gems that span the color spectrum from the iconic sky blue of Turquoise to the fiery, multi-hued brilliance of Zircon and the deep, velvety violet-blue of Tanzanite.
The Historical and Cultural Tapestry of Birthstones
The concept of birthstones is not a modern invention but is rooted in ancient traditions. The earliest known association of gems with a specific group of twelve is found in the biblical account of the High Priest Aaron's breastplate. As described in the Book of Exodus, this sacred garment was adorned with twelve precious stones, each representing one of the twelve tribes of Israel. While the exact identities of these ancient stones are a matter of scholarly debate due to evolving names and translations, many believe they laid the foundation for later birthstone lists. For example, the "sardius" mentioned is often linked to Sardonyx, and "peridot" is believed to have been known in ancient times.
This ancient practice of grouping twelve stones evolved differently across cultures. In the 1st century AD, the Jewish historian Josephus made a connection between the twelve stones of the breastplate and the twelve signs of the zodiac, suggesting that wearing these stones in a specific order could harness their power. This idea was further developed in the 8th and 9th centuries when Christian scholars linked the stones to the apostles, creating a new list that associated a gem with each month.
The modern, standardized list of birthstones, however, is largely a product of commercial and organizational efforts in the early 20th century. In 1912, the National Association of Jewelers (now Jewelers of America) convened to create a standardized list to facilitate trade and provide a consistent guide for consumers. This list, known as the "modern" birthstone list, has been updated several times since, most notably in 1952 and 2002, to include newer stones like Tanzanite. The December stones on this list reflect this evolution: Turquoise is the traditional stone, while Tanzanite was added as a modern choice, and Zircon and Blue Topaz are also recognized as alternatives. The sources provided highlight this diversity, listing "Turquoise, Zircon and Tanzanite" as December's stones, with Blue Topaz also mentioned as a secondary or modern alternative.
Turquoise: The Traditional December Birthstone
Turquoise is arguably one of the most ancient and revered gems in human history. Its distinctive sky-blue to bluish-green color, a result of copper and aluminum phosphates, has been prized by civilizations across the globe for millennia.
History and Lore
The name "turquoise" is derived from the French pierre turquoise, meaning "Turkish stone," as the gem was first brought to Europe from Turkey via Persian trade routes. However, its use predates these routes by thousands of years. Ancient Egyptians mined turquoise as early as 3000 B.C., adorning royalty and pharaohs, including Tutankhamun, with intricate jewelry. In ancient Persia, turquoise was worn as a protective amulet, believed to ward off unnatural death and ensure a safe journey. The stone was also integral to Native American cultures, particularly the Navajo, Zuni, and Pueblo peoples, who have a rich tradition of turquoise jewelry and associate the stone with sky, water, and good fortune.
The lore surrounding Turquoise is extensive. It has long been regarded as a love charm, a symbol of good fortune and success, and a stone capable of relaxing the mind. It was widely believed to protect its wearer from harm, with turquoise rings specifically thought to ward off evil spirits. This protective quality is a recurring theme in its history, making it a popular talisman for warriors and travelers.
Geological Formation and Sources
Turquoise is a hydrous phosphate of copper and aluminum that forms in arid regions where acidic, copper-rich solutions seep through aluminum-bearing rocks and precipitate into veins and nodules. This process can take millions of years. The color of the stone is directly related to its copper content; higher copper levels yield a more vibrant blue, while iron and chromium can contribute to greenish hues.
Major sources of Turquoise include the United States (particularly Arizona, Nevada, and New Mexico), Iran (historically the source of the finest "robin's egg blue" material), and China. The quality of Turquoise is often determined by its color, matrix (the host rock embedded within the stone), and durability. Stabilized Turquoise, where the porous stone is infused with a clear resin to enhance its durability and color, is common in the market.
Gemological Properties
Turquoise is valued for its unique color rather than its brilliance. It is an opaque gem with a waxy to vitreous luster. Its hardness on the Mohs scale is typically between 5 and 6, making it relatively soft and susceptible to scratching and breakage. This necessitates careful handling and setting, often in protective bezel settings for jewelry. Turquoise has a specific gravity of 2.60-2.90 and a refractive index of approximately 1.61. Due to its porosity, it can be sensitive to chemicals, cosmetics, and even the natural oils of the skin, which can cause discoloration over time.
Zircon: The Sparkling Alternative
Zircon is one of the oldest minerals on Earth, dating back billions of years, yet it is often confused with the synthetic cubic zirconia. Natural Zircon is a beautiful and brilliant gem in its own right, prized for its exceptional fire and luster. It is one of the original December birthstones.
History and Lore
Zircon has a long history of use in jewelry, with blue Zircon being particularly popular during the Victorian era. It was believed to bring wisdom, honor, and prosperity to its wearer. In the Middle Ages, Zircon was thought to induce sound sleep, ward off evil spirits, and protect travelers. It was also said to promote prosperity and honor, making it a favored stone for those seeking success. The confusion with cubic zirconia, a 20th-century diamond simulant, has unfortunately overshadowed Zircon's natural beauty in the modern market, but it remains a gem of great historical and aesthetic value.
Geological Formation and Sources
Zircon is a zirconium silicate mineral that forms in igneous and metamorphic rocks. It is highly resistant to weathering and is often found as detrital grains in sedimentary deposits. This durability makes it an important mineral for geological dating (radiometric dating). Zircon occurs in a variety of colors, including red, yellow, green, brown, and blue. The brilliant, fiery blue of Zircon is often achieved through heat treatment of brownish stones. Major sources for gem-quality Zircon include Sri Lanka, Thailand, Cambodia, and Australia.
Gemological Properties
Zircon is one of the heaviest natural gemstones, with a specific gravity ranging from 4.6 to 4.7. This high density gives it significant "weight" in the hand, often making it appear larger than a diamond of the same carat weight. It possesses a very high refractive index (1.92-2.01), which is higher than that of a diamond, contributing to its exceptional brilliance and fire. On the Mohs scale, Zircon has a hardness of 7.5, making it a durable stone suitable for most types of jewelry, though it can be brittle due to its perfect cleavage in two directions. This cleavage means it can be chipped or split by a sharp blow, requiring careful handling.
Tanzanite: The Modern Marvel
Tanzanite is the newest addition to the list of December birthstones, a 20th-century discovery that has rapidly gained immense popularity. Its unique, saturated color and compelling origin story have made it a favorite in contemporary jewelry.
History and Lore
Tanzanite was discovered in 1967 in the Merelani Hills of northern Tanzania, near the base of Mount Kilimanjaro. The gem was initially found by a local Masai herdsman, Ali Juuyawatu, who sold it to a tailor named Manuel d'Souza. D'Souza quickly registered four mining claims, and a rush for the new blue stone began. The gemological community soon identified it as a variety of the mineral zoisite. Tiffany & Co. recognized its potential and became its primary distributor, naming it "Tanzanite" after its country of origin and launching a major marketing campaign in 1968 that cemented its status as a precious gem. The Maasai people, who live near the mining area, associate Tanzanite with life and vitality and believe it brings good fortune.
Geological Formation and Sources
Tanzanite's formation is exceptionally rare. It is a variety of the mineral zoisite that has been heated naturally by geological processes, which caused the substitution of vanadium and/or chromium for other elements in its crystal structure, resulting in its vivid violet-blue color. This specific geological event is believed to have occurred only in a small, single area of Tanzania, making the stone's source location unique. The deposits are found in the lower slopes of Mount Kilimanjaro, and mining is concentrated in four small areas, making the gem geologically limited and potentially finite.
Gemological Properties
Tanzanite is known for its strong trichroism, meaning it displays three different colors when viewed from three different crystallographic directions: blue, violet, and a reddish-brown. The most desirable color is a deep, saturated violet-blue. It is relatively soft compared to other popular gemstones, with a Mohs hardness of 6.5 to 7. This makes it suitable for earrings and pendants but requires more care when set in rings. Its refractive index is relatively low, ranging from 1.69 to 1.70. Most Tanzanite on the market has been heat-treated to remove the brownish component and enhance the blue and violet hues, a stable and permanent treatment that is widely accepted in the industry.
Comparative Gemological Properties
To better understand the physical characteristics of December's birthstones, the following table provides a comparison of their key gemological properties, as derived from established sources.
| Property | Turquoise | Zircon | Tanzanite |
|---|---|---|---|
| Chemical Composition | Hydrous phosphate of copper & aluminum (CuAl₆(PO₄)₄(OH)₈·4H₂O) | Zirconium silicate (ZrSiO₄) | Calcium aluminum hydroxyl sorosilicate (Ca₂Al₃(SiO₄)₃(OH)) |
| Crystal System | Triclinic | Tetragonal | Orthorhombic |
| Mohs Hardness | 5 - 6 | 7.5 | 6.5 - 7 |
| Refractive Index | ~1.61 | 1.92 - 2.01 | 1.69 - 1.70 |
| Specific Gravity | 2.60 - 2.90 | 4.60 - 4.70 | 3.35 |
| Luster | Waxy to Vitreous | Adamantine | Vitreous |
| Transparency | Opaque | Transparent to Translucent | Transparent |
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, all three December stones are steeped in symbolism and metaphysical beliefs, many of which have been passed down through generations.
- Turquoise is widely regarded as a master healing stone. It is believed to align all the chakras, stabilize and center the spirit, and promote self-realization. Its protective lore continues to this day, with many wearing it as a shield against negative energy and accidents. It is also associated with creative expression and the calming of the mind.
- Zircon is said to help its wearer achieve wisdom and honor. It is believed to boost self-confidence and promote prosperity and spiritual growth. In crystal healing, Zircon is thought to aid in overcoming grief and instilling a sense of purpose and dignity.
- Tanzanite is a stone of transformation. It is believed to stimulate the throat chakra, enhancing communication and a more authentic self-expression. As a relatively new stone, its metaphysical properties are more modern, but it is associated with spiritual awakening, intuition, and the expansion of consciousness. It is also considered a stone of abundance and good fortune.
Care and Cleaning
Due to their differing physical properties, the three December birthstones require distinct care regimens.
- Turquoise, being relatively soft and porous, is the most delicate. It should be protected from scratches, chemicals, and extreme heat. Clean it with warm, soapy water and a soft cloth. Avoid ultrasonic cleaners and steam cleaners. It is also advisable to avoid prolonged exposure to lotions, perfumes, and cosmetics, which can cause discoloration.
- Zircon, despite its higher hardness, is brittle due to its cleavage. It should be protected from sharp blows. It is generally safe to clean with warm, soapy water and a soft brush. While it is resistant to most chemicals, prolonged exposure to strong heat or light can cause some brown Zircons to fade.
- Tanzanite, with a hardness of 6.5-7, is moderately durable but should be handled with care. It is best cleaned with warm, soapy water and a soft brush. It should not be subjected to ultrasonic or steam cleaning, as the vibrations or heat can cause fractures. Due to its strong trichroism and the common practice of cutting to maximize its best color, Tanzanite should be protected from hard knocks.
Conclusion
The birthstones of December—Turquoise, Zircon, and Tanzanite—offer a remarkable diversity of color, history, and meaning. From the ancient, protective allure of Turquoise to the fiery brilliance of Zircon and the modern, transformative elegance of Tanzanite, each gem provides a unique connection to the last month of the year. Their stories are woven through millennia of human history, from the sacred breastplates of ancient priests to the crown jewels of empires and the vibrant markets of today. Understanding their geological origins, gemological properties, and rich cultural symbolism allows for a deeper appreciation of these gems, making them not only beautiful adornments but also meaningful companions for those born in December.