The final month of the year is unique in the world of gemology, offering not one, not two, but four distinct birthstones to those born in its grasp. December's birthstones—Turquoise, Tanzanite, Blue Topaz, and Zircon—present a remarkable spectrum of blue hues, from the sky-clear tranquility of topaz to the deep, velvety violet of tanzanite. This abundance provides a rich palette that reflects the crisp clarity of winter, but it also raises questions. Why does December have four stones? How did this list evolve? And how does one choose between them?
This comprehensive guide delves into the history, geology, and gemological properties of each of December's official birthstones. We will explore their ancient origins, their modern commercial ascent, and the unique characteristics that define them. For the gemstone enthusiast, the prospective jewelry buyer, or the student of mineralogy, understanding these four gems is key to appreciating the full story behind December's dazzling birthstone collection.
The Historical Evolution of December's Birthstones
The modern concept of birthstones is rooted in ancient traditions, but the list we recognize today has been shaped as much by commerce and discovery as by history. The journey to the current four-stone lineup for December is a fascinating story of evolution.
Traditional Roots: Turquoise and Zircon
For centuries, Turquoise and Zircon were the primary stones associated with December. Turquoise, with its distinctive blue-green color, has a history stretching back millennia. Its name, as noted in historical accounts, derives from the French phrase pierre turquoise, meaning "stone of Turkey." This nomenclature arose because the stone was brought to Europe from Turkish bazaars, having traveled along ancient trade routes from its source mines in Persia and the Sinai Peninsula.
Zircon, too, has a long and storied past, though its history is sometimes complicated by confusion with other gemstones. For much of history, the term "zircon" was used interchangeably with "jacinth," a name for the orange-brown variety. Despite this, blue zircon has been a known and appreciated gem for centuries, valued for its brilliance and fire.
The Standardization of Birthstones
The formalization of birthstones as we know them began in the early 20th century. In 1912, the National Association of Jewelers (now known as the Jewelry Industry Council of America) sought to standardize the unofficial list of American birthstones. This was a pragmatic move, designed to combine traditional customs with gemstones that were practical and commercially viable for jewelry companies to sell.
This initial list placed Turquoise as the birthstone for December. However, the list was not static. In 1952, the Jewelry Industry Council of America made a significant update, adding Blue Zircon to December’s list of official stones. This was one of the first major expansions, acknowledging the gem's growing popularity and availability.
Modern Additions: Tanzanite and Blue Topaz
The late 20th and early 21st centuries brought new discoveries and shifting consumer tastes, leading to further additions. The most dramatic of these was the discovery of Tanzanite in the 1960s. This vivid blue-violet gem, found in a single, tiny area of Tanzania, quickly captured the market's imagination. Its rarity and unique color made it a prized possession. Recognizing its significance, the Jewelry Industry Council of America added Tanzanite to the official December birthstone list in 2002.
Blue Topaz represents a different path to becoming a December birthstone. While topaz itself is an ancient gem, the vibrant, saturated blue that is so popular today is largely a product of modern gemological treatments (a fact that will be explored in detail later). Its affordability, durability, and brilliant color made it an increasingly popular choice for jewelry, especially in the United States. While not always on the "official" list, it has become so mainstream and commercially important that it is now widely accepted as a fourth December birthstone, often listed as an "alternative" or co-official gem. Some sources suggest that the expansion to four stones was partly to offer consumers more affordable options alongside the rarer and more expensive gems like Tanzanite.
Geological Formation and Global Sources
Each of December's four birthstones has a unique geological story and originates from distinct regions of the world. Understanding their formation and sources provides insight into their rarity and character.
Turquoise: The Mineral of Groundwater
Turquoise is not formed by the slow cooling of magma like many gems, but rather through a process of precipitation. It is a secondary mineral that forms when water containing copper and aluminum seeps through bedrock. Over long periods, this groundwater reacts with existing minerals, precipitating the opaque, blue-to-green phosphate of copper and aluminum that we know as Turquoise. The presence of copper typically yields a blue color, while iron and other impurities can shift the hue toward green.
The dark veins and web-like patterns often seen in Turquoise are known as matrix. This is the remnants of the host rock (often iron pyrite or sandstone) that were not fully replaced during the turquoise formation process. Historically, significant sources were found in Persia (modern-day Iran) and the Sinai Peninsula. Today, major mining operations are located in the Southwestern United States (especially Arizona and New Mexico), China, and other locations. The stone was so integral to the culture of the Native Americans of the Southwest that they associated it with youth and strength.
Tanzanite: The Single-Source Wonder
Tanzanite is one of the most geographically restricted gems in the world. It is a variety of the mineral zoisite and is formed from the metamorphism of pre-existing rocks. Its formation required a unique and specific set of geological conditions that occurred only in a small, four-square-kilometer area in the Merelani Hills of northern Tanzania. This extreme rarity is the primary reason for its high value and expense. As stated in the sources, "It is the rarest, since it’s only mined in a specific region of Tanzania." To date, no other significant source of gem-quality tanzanite has been discovered, cementing its status as a true gemological treasure.
Blue Topaz: From Colorless to Vibrant Blue
Topaz is a silicate mineral that forms in igneous rocks, particularly in cavities within granite and rhyolite. Its natural color range is extensive, including yellow, brown, blue, pink, and colorless. The pure, intense blue that is most sought after for December birthstone jewelry is rarely found in nature. The vast majority of commercially available blue topaz begins as a colorless or lightly colored natural topaz crystal. These crystals are then subjected to irradiation followed by heat treatment, a process that develops the deep, saturated blue. This treatment is stable and permanent, and it is a standard industry practice that makes this beautiful gem widely available.
The sources note that blue topaz is mined in several countries, including Sri Lanka, Brazil, Mexico, Nigeria, and the United States. Its status as the official state gem of Texas highlights its particular popularity in the U.S.
Zircon: The Oldest Mineral on Earth
Zircon is a mineral belonging to the group of nesosilicates. It is the oldest known mineral on Earth, with some crystals dating back over 4.4 billion years, making them invaluable to geologists for dating the formation of our planet. While it occurs in a wide range of colors, the blue variety is the one associated with December. Natural blue zircon is rare; most of the vivid blue stones on the market have been heat-treated from brownish zircon crystals. This process is also stable and widely accepted. Zircon is mined in many locations worldwide, including Australia, Sri Lanka, Thailand, and Cambodia.
Gemological Properties: A Comparative Analysis
For jewelers and buyers, the physical properties of a gemstone are paramount. Durability, color, and brilliance determine how a stone will wear over time and how it should be set and cared for. The four December birthstones offer a wide range of these characteristics.
| Gemstone | Mohs Hardness | Chemical Formula | Key Characteristics |
|---|---|---|---|
| Blue Topaz | 8 | Al₂SiO₄(F,OH)₂ | Excellent durability for daily wear. Often treated to achieve its deep blue color. |
| Zircon | 6.5 - 7.5 | ZrSiO₄ | High refractive index gives it exceptional brilliance and fire. Can be brittle. |
| Tanzanite | 6 - 6.5 | Ca₂Al₃(SiO₄)₃(OH) | Trichroic (shows three colors: blue, violet, and burgundy). Requires careful handling. |
| Turquoise | 5 - 6 | CuAl₆(PO₄)₄(OH)₈·4H₂O | Opaque, relatively soft, and porous. Often stabilized or treated. |
Durability and Wearability
When it comes to everyday wear, durability is a key consideration. The sources are explicit on this point: "Blue topaz is the most durable December birthstone for everyday wear. Of all the December birthstones, blue topaz is the hardest on the Mohs hardness scale at an 8." A hardness of 8 means it is resistant to scratching and is an excellent choice for rings, bracelets, and other pieces that may be subject to knocks.
Zircon, with a hardness of 6.5 to 7.5, is also quite durable, though it can be more brittle due to its crystal structure. Its exceptional brilliance (a high refractive index) makes it a popular diamond simulant.
Tanzanite (6-6.5 on the Mohs scale) is less hard than topaz or zircon and is more susceptible to scratches and abrasions. Its cleavage (the tendency to break along flat planes) is also a consideration, making it a gem that requires a protective setting, especially for rings. It is often recommended for pendants and earrings.
Turquoise, at 5 to 6 on the Mohs scale, is the softest of the group. It is also porous, meaning it can absorb oils, dirt, and chemicals, which can discolor it over time. Because of this, turquoise is often treated with resins and waxes to stabilize its color and increase its durability. It is best suited for pieces that are not subject to daily wear and tear or for items like beads that are less likely to be struck.
Color and Appearance
The color blue is the unifying theme for all four gems, but each presents it differently. * Turquoise is known for its opaque, sky-blue to blue-green color, often interspersed with a brown or black matrix. * Tanzanite displays a mesmerizing range of blues and violets. It is famously trichroic, meaning it can show three different colors—blue, violet, and a reddish-brown—from different crystallographic directions. The most prized color is a deep, saturated violetish blue. * Blue Topaz comes in a variety of shades, from the pale Sky Blue to the deeper Swiss Blue and the very deep London Blue. These are all results of the treatment process applied to colorless topaz crystals. * Blue Zircon is known for its brilliant fire and sparkle, often rivaling that of diamond. Its blue can range from a light, airy blue to a more intense greenish-blue.
Symbolism, Lore, and Metaphysical Beliefs
Beyond their physical beauty, gemstones have been imbued with meaning and power for centuries. Each of December's birthstones carries a rich tapestry of symbolism and lore.
The Protective Power of Turquoise
Turquoise is perhaps the most storied of the four in terms of ancient beliefs. It was considered a powerful amulet, valued for its perceived ability to protect the wearer from danger and bring good fortune. The sources highlight several fascinating beliefs: * It was believed to warn its wearer of approaching illness or danger by becoming pale, a property that made it highly valued as a diagnostic tool. * It was a gem of choice for lovers and married couples, thought to protect relationships and preserve friendship if given as a gift. * Tibetans considered it a birthstone of fortune, health, and success, and it was so valued that it was used as a form of currency. * In ancient cultures, it was a sacred offering. Ancient Incas and Mayas offered turquoise to their gods. * Native Americans of the Southwest associated the stone with youth and strength.
The Modern Appeal of Tanzanite and Topaz
Tanzanite, being a modern discovery, has more contemporary symbolic meanings. It is often associated with transformation and new beginnings, reflecting its unique geological birth. Its alluring color is said to promote a higher consciousness and intuition.
Blue Topaz has long been associated with love and affection. In some beliefs, it is thought to have a calming influence, helping to soothe tempers and release tension. Its clear, bright color is often linked to clarity of thought and communication.
The Clarity and Wisdom of Zircon
Zircon, one of the oldest minerals on Earth, has historically been associated with wisdom and honor. It was believed to help its wearer achieve wealth and honor through wisdom. Its brilliant sparkle was thought to be a reflection of a clear and disciplined mind.
Care and Cleaning: Preserving Your December Gem
Proper care is essential to maintain the beauty and longevity of any piece of gemstone jewelry. Given the varying properties of the December birthstones, their care requirements differ significantly.
Caring for Durable Gems: Blue Topaz and Zircon
Thanks to its high hardness, Blue Topaz is relatively easy to care for. It can be safely cleaned with warm water, a mild soap, and a soft brush. It is resistant to most chemicals and can withstand the ultrasonic cleaner, although steam cleaning should be approached with caution.
Zircon is also fairly durable but can be brittle. While it can be cleaned with warm soapy water and a soft brush, it is best to avoid ultrasonic and steam cleaners, as the vibrations or sudden temperature changes could potentially fracture the stone, especially if it has any inclusions.
Handling More Delicate Stones: Tanzanite and Turquoise
Tanzanite requires more careful handling due to its lower hardness and perfect cleavage. It should never be put into an ultrasonic cleaner, and steam cleaning is also a risk. The safest method is warm, soapy water and a soft brush. When not being worn, store it separately to avoid scratches from harder gems.
Turquoise is the most delicate of the four. It is porous and sensitive to chemicals, including those found in cosmetics, lotions, and even some soaps. Cleaning should be done gently with a soft, dry or slightly damp cloth. Avoid any harsh chemicals, ultrasonic cleaners, and steam. Over time, turquoise can change color, and proper care will help preserve its iconic blue-green hue.
Conclusion
The birthstones of December—Turquoise, Tanzanite, Blue Topaz, and Zircon—offer an unparalleled choice for those born in the last month of the year. Their collective story is one of ancient tradition, modern discovery, and commercial evolution. From the protective amulets of ancient Persia to the single-source marvel of Tanzania, each gem carries a unique narrative.
For the consumer, this diversity means the ability to select a stone based on personal preference, budget, and lifestyle. The unparalleled durability of Blue Topaz makes it an ideal choice for everyday rings, while the legendary history of Turquoise connects the wearer to millennia of human culture. The breathtaking rarity of Tanzanite offers a piece of a unique geological wonder, and the brilliant fire of Zircon provides exceptional sparkle.
Ultimately, the expansion of the December birthstone list is a testament to the dynamic nature of gemology—a field where history, science, and human desire intersect. Whether chosen for its color, its lore, or its durability, any of the four December gems can serve as a beautiful and meaningful symbol for those who claim it as their own.