For those born in the final month of the year, December offers a unique and vibrant selection of birthstones. Unlike many months with a single primary gem, December is celebrated with three distinct and captivating choices: the ancient and opaque turquoise, the modern and vivid tanzanite, and the brilliant and multi-colored zircon. This trio provides a spectrum of color, from the sky-blue and green of turquoise to the bluish-purple of tanzanite and the rainbow hues of zircon. Each gem possesses its own rich history, geological origin, and set of characteristics, allowing individuals to select a stone that truly reflects their personality and style. The following exploration delves into the history, lore, geology, and gemological properties of these three remarkable December birthstones, providing a comprehensive guide for enthusiasts, collectors, and anyone captivated by the beauty of these gems.
History and Lore of Turquoise
Turquoise is a semi-translucent to opaque gem that ranges in color from blue to green, often featuring distinctive veins of matrix—the remnants of the host rock in which it formed. This December birthstone has been cherished for millennia, with a history that spans ancient civilizations and continents. The pharaohs and other rulers of ancient Egypt adorned themselves with turquoise jewelry, and Chinese artisans were carving the stone more than 3,000 years ago. Its legacy extends to the funerary mask of King Tut, who ruled Egypt over three millennia ago, demonstrating its esteemed status in antiquity.
The cultural significance of turquoise is profound and varied. In European tradition, the gift of a turquoise ring is said to mean "forget me not." For the Pueblo people, the gem was believed to derive its color from the sky, while the Hopi thought it was produced by lizards scurrying over the earth. In Tibet, turquoise is considered a national treasure, believed to grant health, good fortune, and protection from evil, while also imparting peace to the wearer. This December birthstone also marks the 11th wedding anniversary. More recently, it adorned the famous amethyst and turquoise necklace made by Cartier for Wallis Simpson, the Duchess of Windsor.
The belief in turquoise's beneficial powers is a recurring theme. It was historically thought to possess many virtues, like guaranteeing health and good fortune. This long-standing association with well-being and protection has cemented its place not only as a birthstone but as a talisman across cultures.
Geological Formation and Sources of Turquoise
Turquoise is a phosphate mineral that forms when water containing copper and aluminum seeps through rocks like granite or shale. The resulting mineral is porous and often contains the host rock matrix, which gives it its characteristic veined appearance. Historically, one of the most renowned sources for high-quality turquoise is the Nishapur district in Iran, which has been mined for over 1,000 years. This region is known for producing a distinct, often sky-blue gem with a fine matrix.
In the United States, the Sleeping Beauty mine in Arizona was a prolific producer for more than four decades. However, this mine is now closed to turquoise mining. Today, the landscape of turquoise production has shifted significantly. China has emerged as the world's largest producer of this December birthstone. The Hubei Province, located in central China, is the source of most of the gem-quality turquoise currently being mined. The availability of material from these diverse locations means that the color, matrix, and overall quality of turquoise can vary widely, offering a broad selection for jewelry buyers.
Gemological Properties of Turquoise
Understanding the physical characteristics of turquoise is essential for its proper care and appreciation. As a gemstone, it is relatively soft compared to many other jewels, which affects its use in jewelry.
- Hardness: Turquoise has a Mohs hardness of 5 to 6. This places it in the range where it can be susceptible to scratching and abrasion from everyday objects. As such, it requires careful handling to maintain its polish and surface integrity.
- Durability and Treatments: Due to its porosity and relative softness, some turquoise is treated to improve its durability and appearance. Common treatments include dyeing to enhance or alter color, and the application of an epoxy or acrylic resin to increase hardness and improve polish. Another treatment involves filling cavities with a metal-loaded epoxy to imitate pyrite inclusions, a practice that affects the stone's appearance and value.
- Stability and Care: Turquoise is generally stable when exposed to light. However, it is sensitive to heat, which can cause discoloration and breakage. The gem is also vulnerable to damage from acids and can be discolored by certain chemicals, cosmetics, and even skin oils or perspiration. For cleaning, it is safe to use warm, soapy water and a soft brush. However, turquoise should never be cleaned with steam or ultrasonic cleaners, as the vibrations and heat can damage the stone or any resin treatments it may have undergone.
History and Lore of Tanzanite
Tanzanite is a relatively modern addition to the world of colored gemstones, yet it has quickly gained immense popularity as a December birthstone. It is prized for its distinct and captivating bluish-purple color, a hue that is unique to this gem. While its official recognition is recent, its appeal lies in its vibrant color and the story of its singular origin.
Geological Formation and Sources of Tanzanite
The geological story of tanzanite is as unique as its color. It is a variety of the mineral zoisite and is found in only one location in the world: the Merelani Hills of northern Tanzania, near the base of Mount Kilimanjaro. This extremely limited source of origin contributes to its allure and value. The gem is formed through a complex geological process involving heat and pressure, which transforms the parent rock and creates the conditions for tanzanite crystals to grow. The scarcity of this specific geographic location means that all commercial tanzanite comes from this small area, making it a truly exclusive gemstone.
Gemological Properties of Tanzanite
Tanzanite's gemological properties make it a beautiful but delicate gem, requiring specific settings and care.
- Hardness and Durability: On the Mohs scale, tanzanite has a hardness of approximately 6.5 to 7. While this is harder than turquoise, it is still not as durable as gems like sapphire or diamond. It has poor toughness due to its cleavage, meaning it can split or fracture if struck with force. Because of this, tanzanite is best set in protective jewelry such as earrings or pendants. While not recommended for daily wear in a ring, with a protective mounting and careful handling, it can be worn as a special-occasion jewel.
- Color and Treatment: The desirable bluish-purple color of tanzanite is often the result of heat treatment, a standard and permanent practice in the gem trade. Heating the brownish zoisite crystals at specific temperatures permanently transforms their color to the vibrant blue-purple for which tanzanite is known. This treatment is stable and does not affect the stone's durability.
- Stability and Care: Tanzanite is generally stable when exposed to light and chemicals. However, it is sensitive to sudden temperature changes and physical shock. The best method for cleaning tanzanite is with warm, soapy water and a soft brush. As with turquoise, ultrasonic and steam cleaners are never recommended for tanzanite, as the vibrations and heat can cause damage.
History and Lore of Zircon
Zircon is one of the oldest minerals on Earth, with zircon crystals dating back billions of years. Despite its ancient origins, its name and history are subject to colorful debate. Some scholars believe the word "zircon" derives from the Arabic zarkun, meaning "cinnabar" or "vermilion," while others trace it to the Persian zargun, meaning "gold colored." Both etymologies are fitting, as zircon boasts an exceptionally broad color palette that includes red, orange, yellow, brown, green, and blue. This diversity makes it a versatile and fascinating December birthstone.
Zircon should not be confused with the synthetic material cubic zirconia (CZ), which is a diamond simulant. Natural zircon is a distinct and valuable gemstone in its own right, prized for its high refractive index and brilliance, which rivals that of diamond.
Geological Formation and Sources of Zircon
Zircon is a zirconium silicate mineral that forms in igneous and metamorphic rocks. It is often found as a detrital mineral in sedimentary deposits, having weathered from its original host rock. Its durability allows it to survive through geological cycles, making it a common mineral in many parts of the world.
Several countries are known for producing gem-quality zircon. Sri Lanka, particularly the Elahera region in its central part, is one of the country's most productive areas for zircon. The gem is often located near sapphire sources, and this overlap occurs in other countries as well, including Myanmar, Vietnam, and Cambodia.
Australia is another significant source, with the Harts Range in the Northern Territory known for producing zircon in yellow-brown, orangy brown, pink, and purple hues. The specific mining area is known as Zircon Hill, near the city of Alice Springs. The landscape there features open savannahs, dry stream beds, and low-lying hills.
Gemological Properties of Zircon
Zircon is a gem of remarkable brilliance, but it has characteristics that require consideration for jewelry use and care.
- Hardness and Durability: Zircon ranks from 6 to 7.5 on the Mohs scale of hardness. While this makes it reasonably durable, it is also brittle and has poor toughness, meaning it can chip or abrade with impact. This tendency to abrade makes it less suitable for jewelry that will be subjected to rough conditions, such as rings for daily wear. It is best to avoid wearing zircon while gardening, playing sports, or doing dishes to prevent damage.
- Color and Treatment: A significant portion of the blue and colorless zircon on the market is the result of heat treatment. This process can also produce orange, yellow, and red varieties. Heat treatment is a standard and accepted practice in the gem trade.
- Stability and Care: Zircon is generally stable when exposed to light, but some heat-treated stones may revert to their original colors (usually light brown) after prolonged exposure to bright light. The gem is stable when exposed to chemicals. For cleaning, use a soft brush and mild soap in warm water. Ultrasonic and steam cleaners are not recommended for zircon due to its brittleness and the risk of fracture from vibrations or thermal shock.
Comparative Summary of December Birthstones
The three December birthstones—Turquoise, Tanzanite, and Zircon—offer a distinct range of colors, origins, and properties. The following table provides a comparative overview based on the information from the provided sources.
| Feature | Turquoise | Tanzanite | Zircon |
|---|---|---|---|
| Primary Color(s) | Blue to Green | Bluish-Purple | Blue, Colorless, Orange, Yellow, Red, Brown, Green |
| Hardness (Mohs) | 5 - 6 | ~6.5 - 7 | 6 - 7.5 |
| Key Properties | Opaque to semi-translucent, often with matrix (veins). | Pleochroic (shows different colors from different angles). | High refractive index and brilliance. Can be heat-treated for color. |
| Notable Sources | Iran (Nishapur), China (Hubei), USA (Arizona - historic) | Tanzania (Merelani Hills) | Sri Lanka (Elahera), Australia (Harts Range), Myanmar, Vietnam, Cambodia |
| Primary Care Concern | Sensitive to heat, acids, chemicals, and ultrasonic cleaners. | Sensitive to physical shock and thermal shock. Avoid ultrasonic/steam cleaners. | Brittle; prone to chipping and abrasion. Avoid rough wear and ultrasonic/steam cleaners. |
| Historical/Cultural Note | Cherished for millennia; used in ancient Egypt and China; national treasure in Tibet. | A modern gem discovered in the 20th century. | One of Earth's oldest minerals; name origin debated. |
Care and Cleaning for December Birthstones
Proper care is crucial for maintaining the beauty and longevity of these gemstones, given their unique physical properties. The general rule for all three is to avoid harsh chemicals, extreme temperatures, and ultrasonic or steam cleaners.
For turquoise, which is the softest and most porous of the trio, gentle cleaning with warm, soapy water is essential. Protect it from impact, acids, and cosmetics. Its porosity means it can absorb liquids and oils, potentially leading to discoloration over time.
Tanzanite, while harder, is brittle and has perfect cleavage in one direction. It should be handled with care to avoid sharp blows. It is best cleaned with a soft brush and mild soapy water. Due to its cleavage, it is not recommended for rings worn daily unless set in a protective, bezel-style mounting.
Zircon requires caution due to its brittleness and tendency to abrade. While it can withstand daily wear more than turquoise, it is best suited for earrings, pendants, or occasional-wear rings. Cleaning should be done gently with a soft brush and mild soap, avoiding any mechanical or thermal stress that could cause fracture.
Conclusion
December's birthstones present a remarkable trio of gems, each with a unique identity. Turquoise offers a connection to ancient history and cultural lore, with its earthy, opaque beauty and protective symbolism. Tanzanite provides a modern, vibrant splash of color with a singular geological origin, captivating with its bluish-purple brilliance. Zircon, an ancient mineral, dazzles with its diamond-like fire and a spectrum of natural colors, from fiery reds to serene blues. Together, they ensure that anyone born in December has a gemstone that not only marks their birth month but also reflects a rich tapestry of geological wonder, human history, and personal style. By understanding their distinct histories, sources, and properties, one can make an informed choice and appreciate the enduring allure of these three exceptional gems.