December is a unique month in the gemological calendar, distinguished by its official recognition of four distinct birthstones. This abundance offers those born in the final month of the year a remarkable choice of gems, each characterized by captivating blue hues that echo the cool tones of winter. The four December birthstones—Tanzanite, Turquoise, Blue Zircon, and Blue Topaz—each possess a unique history, set of gemological properties, and cultural significance. From the ancient allure of Turquoise to the relatively recent discovery of Tanzanite, these stones provide a rich tapestry of history and science for enthusiasts, collectors, and anyone seeking a meaningful connection to their birth month. This guide delves into the origins, properties, symbolism, and care of these four beautiful blue gemstones, drawing upon historical records, geological data, and cultural lore to present a complete overview for the modern gemologist.
The Historical Evolution of December's Birthstones
The tradition of associating specific gemstones with birth months has ancient roots, with origins traced back to Mesopotamia and later formalized by the Greeks and Romans. The modern list of birthstones has evolved over centuries, with the December selection being a prime example of this progression. Originally, the choice for December was limited primarily to Turquoise and Zircon. These two stones held historical precedence for their beauty and perceived powers.
A significant shift occurred in the 20th century as the jewelry market expanded and new gemological discoveries were made. The list of official birthstones was expanded to reflect these changes and to offer consumers more variety. Blue Topaz was introduced as an alternate, followed by Tanzanite, which is the most recent addition to the official December list, being adopted in 2002. This evolution from two to four stones underscores the dynamic nature of the birthstone tradition, which now encompasses both ancient and modern gems, ensuring a perfect match for every preference within the month.
Tanzanite: A Modern Marvel of Violet-Blue
Tanzanite is the most recent addition to the December birthstone family, yet it has quickly become a favorite for its unique color and compelling origin story. It is considered a modern birthstone for December, often selected for its vibrant, transformative appearance.
Geological Formation and Origin Tanzanite's origin is as singular as its color. It is found in only one location on Earth: a small, mining area in the Merelani Hills of Northern Tanzania, near the base of Mount Kilimanjaro. This extreme geographic limitation makes it exceptionally rare. Geologically, it is a variety of the mineral zoisite and owes its signature violet-blue to the presence of vanadium. The gem's color is often enhanced through a controlled heating process, which removes the brownish undertones and brings out its desirable saturated blue and violet hues.
Gemological Properties Tanzanite is a relatively recent discovery, which means its gemological properties are well-documented. It has a Mohs hardness of 6.5 to 7, making it suitable for jewelry but requiring some care to avoid scratches and sharp blows. It exhibits strong pleochroism, meaning it displays different colors when viewed from different angles—typically blue, violet, and a reddish hue. Its refractive index is moderate, and it can be found in impressive sizes, offering a large, brilliant stone for a relatively accessible price point compared to other blue gems.
Symbolism and Lore Given its modern status, Tanzanite lacks the millennia of lore associated with Turquoise or Zircon. However, it has quickly accrued its own symbolic meanings. It is often associated with transformation, intuition, and spiritual awakening. Its unique trichroic nature is sometimes seen as a metaphor for the interconnectedness of mind, body, and spirit. For those born in early December, Tanzanite is said to embody the "transformation and winter magic" of the season, offering a connection to higher consciousness and a unique spiritual energy.
Turquoise: The Ancient Stone of Protection
Turquoise is the primary and traditional birthstone for December, boasting a history of human use and admiration that spans thousands of years. Its sky-blue to greenish-blue color has made it one of the most recognizable and culturally significant gems in the world.
Geological Formation and Sources Turquoise is an opaque, semi-translucent phosphate mineral that forms in arid regions as water percolates through rocks, carrying minerals that eventually crystallize. Its distinctive color ranges from sky blue to greenish-blue, often influenced by the presence of copper (blue) and iron (green). The gem is frequently found with a matrix of brown or black veins, known as spiderwebs, which are remnants of the host rock. Major sources for high-quality Turquoise include Iran, the United States (particularly Nevada and Arizona), Tibet, and India. Each region produces stones with characteristic colors and matrix patterns.
Gemological Properties Turquoise is a relatively soft gem, with a Mohs hardness of 5 to 6. This makes it more susceptible to scratching and damage than harder stones like Topaz or Zircon. It is typically cut en cabochon to best display its color and any matrix patterns. Due to its porosity, Turquoise is often stabilized or treated with wax to enhance its durability and color. Its opacity and unique waxy luster distinguish it from the transparent gems also associated with December.
History and Lore Turquoise is one of the oldest gemstones known to humanity, with artifacts dating back to ancient Egypt and Mesopotamia. It was revered by numerous cultures for its purported protective powers. Native American tribes, such as the Navajo, Zuni, and Pueblo, have a profound spiritual connection to the stone, using it in ceremonies and as a powerful emblem of protection and good fortune. The ancient Egyptians inlaid Turquoise in burial masks, including that of Tutankhamun, believing it offered protection in the afterlife. A historical belief from the 13th century held that the stone could protect a person from falling, leading to its use on horse bridles. It was also thought to change color to warn its wearer of impending danger or illness, and Hindu mystics believed seeing Turquoise after a new moon would bring wealth.
Zircon: The Fire and Brilliance of a Traditional Gem
Blue Zircon is the traditional alternate birthstone for December, a gem prized for its exceptional brilliance and fire, which rivals that of diamond. It is often confused with the synthetic cubic zirconia, but natural Zircon is a distinct and ancient mineral with its own unique properties and lore.
Geological Formation and Sources Zircon is a mineral belonging to the zirconium silicate group. It is one of the oldest minerals on Earth, with crystals found in Australia that are over 4.4 billion years old. While Zircon occurs in a variety of colors, the blue variety is the one associated with December. This blue color is typically achieved through a heat-treatment process of brownish Zircon crystals. Major sources for Zircon include Cambodia, Sri Lanka, and Thailand. It forms in igneous and metamorphic rocks and is known for its high refractive index.
Gemological Properties Zircon is a hard and dense gem, with a Mohs hardness of 7.5. However, it is known for being somewhat brittle due to its perfect cleavage in two directions, making it susceptible to chipping if struck. Its most notable property is its high refractive index (around 1.95), which gives it a brilliant luster and exceptional fire, exceeding that of most other colored gemstones. This brilliance makes it a popular and affordable alternative to diamonds. The heat treatment used to produce the desirable blue color is stable and widely accepted in the gem trade.
Symbolism and Lore Zircon has a long history of metaphysical associations. For those born in late December, it is said to harness the "brilliance and new year energy," symbolizing new beginnings and clarity. Historically, Zircon was believed to promote honor, purity, and wisdom. It was also thought to aid in sleep and bring prosperity. The stone's fiery sparkle has long been associated with spiritual awakening and the pursuit of truth.
Blue Topaz: The Modern, Durable Choice
Blue Topaz is a popular modern birthstone for December, celebrated for its brilliant clarity, range of blue shades, and excellent durability. Its availability in large, clean crystals makes it an attractive and affordable option for a wide variety of jewelry designs.
Geological Formation and Sources Topaz is a silicate mineral that forms in igneous rocks, particularly in pegmatites and vapor-rich cavities in rhyolite. While natural blue Topaz does occur, most of the vibrant blue material on the market is created by irradiating and heat-treating colorless Topaz. The process enhances the stone's natural properties to produce the deep, saturated blues known as Swiss Blue or Sky Blue. Major sources for Topaz include Brazil, Sri Lanka, and Nigeria.
Gemological Properties Blue Topaz is the hardest of the December birthstones, with a Mohs hardness of 8. This makes it highly resistant to scratching and suitable for daily wear in all types of jewelry. It is a transparent gem with a vitreous luster and a relatively high refractive index, giving it a bright, sparkling appearance. One of its key characteristics is its perfect basal cleavage, meaning it can be chipped or split along certain planes if subjected to a sharp blow, so it requires careful handling despite its hardness.
Symbolism and Lore As a modern birthstone, Blue Topaz does not have the ancient history of Turquoise or Zircon, but it has come to be associated with qualities of calm, clarity, and communication. Its cool blue color is linked to serenity and peace. It is often seen as a stone that can soothe the mind and aid in clear expression. Its durability and bright, cheerful color make it a favorite for gifts and everyday wear.
Comparing the Gemological Properties
To better understand the distinct characteristics of each of the four December birthstones, a comparison of their key gemological properties is useful. This table, based on information from gemological sources, highlights the differences in hardness, color, and treatment.
| Gemstone | Mohs Hardness | Chemical Composition | Typical Color | Common Treatments |
|---|---|---|---|---|
| Tanzanite | 6.5 - 7 | Ca2Al3(SiO4)3(OH) | Violet-Blue | Heating |
| Turquoise | 5 - 6 | CuAl6(PO4)4(OH)8·4H2O | Sky Blue to Greenish-Blue | Stabilization, Waxing |
| Zircon | 7.5 | ZrSiO4 | Blue (often from brown) | Heating |
| Blue Topaz | 8 | Al2SiO4(F,OH) | Sky Blue to Deep Blue | Irradiation, Heating |
This comparison clearly illustrates why Blue Topaz is considered the most durable for daily wear, while Turquoise requires the most care. It also shows the variety in chemical makeup and the common industry practices used to enhance the natural beauty of these gems.
Care and Cleaning for December Birthstones
Proper care is essential to maintain the beauty and longevity of any gemstone. The four December birthstones have different levels of durability and require specific cleaning methods.
- Tanzanite (Hardness 6.5-7): Due to its moderate hardness and cleavage, Tanzanite should be protected from hard knocks. It is best cleaned with warm, soapy water and a soft brush. Avoid ultrasonic cleaners and steam cleaning, as the heat and vibrations can cause damage.
- Turquoise (Hardness 5-6): As the softest of the group, Turquoise is susceptible to scratches and damage from chemicals. It should be wiped with a soft, dry cloth. Avoid exposing it to cosmetics, perfumes, and even prolonged sunlight, which can cause fading or discoloration. Soapy water and a soft brush can be used, but it should be dried thoroughly.
- Zircon (Hardness 7.5): Although Zircon is hard, it is brittle and has perfect cleavage. It should never be subjected to ultrasonic cleaning or steam cleaning. The best method is warm, soapy water with a soft brush. Take care to avoid sharp blows that could chip the stone.
- Blue Topaz (Hardness 8): While Topaz is very hard, it has perfect cleavage, making it vulnerable to sharp impacts. It can be safely cleaned with warm, soapy water and a soft brush. However, it should be kept away from ultrasonic cleaners and sudden, extreme temperature changes, which can cause the stone to fracture along its cleavage planes.
Conclusion
The four birthstones of December—Tanzanite, Turquoise, Blue Zircon, and Blue Topaz—offer an unparalleled selection for those born in the last month of the year. Each stone provides a unique window into the world of gemology, from the ancient, protective lore of Turquoise to the singular, modern discovery of Tanzanite. Zircon offers brilliant fire and a connection to the planet's most ancient history, while Topaz provides a durable and affordable option with a clear, bright hue. Together, they represent a spectrum of blue that captures the essence of winter's calm and the festive spirit of the season. Whether chosen for their historical significance, symbolic meaning, or simply their captivating beauty, these gems provide a meaningful and lasting connection to the month of December.