The final month of the Gregorian calendar is unique in the world of gemology, offering not one, but four distinct birthstones. December is the only month with this many official options, a fact that reflects both historical evolution and modern commercial adaptation. The four gems—Turquoise, Zircon, Tanzanite, and Blue Topaz—are united by a common chromatic theme: a palette of blues, greens, and violets that vividly mirrors the cool, serene hues of the winter season. This abundance provides December-born individuals with a spectrum of choices, ranging from ancient, opaque treasures to brilliant, transparent modern gems. Each stone carries its own deep history, geological origin, and set of symbolic meanings, creating a rich tapestry for enthusiasts, collectors, and jewelry buyers to explore.
The journey to this four-gem collection was not instantaneous. The modern list is the result of a century-long process of standardization and expansion. The first major step occurred in 1912, when the National Association of Jewelers (now the Jewelry Industry Council of America) standardized the unofficial American birthstones. This list combined long-standing customs with gemstones deemed practical for the jewelry industry to sell. Over the decades, this list has been updated to include new discoveries and shifting market trends. In 1952, the Jewelry Industry Council of America added zircon to December’s list, while tanzanite, a relative newcomer to the gem market, was officially added in 2002. Blue topaz, while not always listed on the earliest official charts, has gained significant popularity and is now widely recognized as a mainstream December birthstone. This article will delve into the history, geology, gemological properties, and cultural significance of each of these four remarkable stones, providing a detailed guide to the gems of December.
The Historical and Cultural Journey of December's Birthstones
The concept of birthstones has ancient roots, tracing back to the biblical description of the High Priest Aaron’s breastplate, which was adorned with twelve gemstones representing the twelve tribes of Israel. This tradition evolved, with different cultures assigning specific stones to months, zodiac signs, or even days of the week. December, in particular, has a complex and varied history, with several stones holding the title across different calendars and cultures.
Turquoise stands as the oldest and most traditional December birthstone. Its association with the month is evident in the 18th-century Gregorian birthstone poem: “If cold December gave you birth, / The month of snow and ice and mirth, / Place on your hand a turquoise blue; / Success will bless whate’er you do.” This gem was an ancient birthstone for December in the old Polish and Russian calendars. Before this, it served as a zodiac stone for Sagittarius, a sign that spans late November and December. The stone’s journey into Western calendars is deeply embedded in history, cherished for millennia by royalty and commoners alike. Its enduring popularity is a testament to its unique color and the lore that surrounds it.
Zircon also carries a traditional mantle. It was the December birthstone in the old Indian calendar and was officially added to the modern U.S. list in 1952, where it replaced lapis lazuli. Its history is often intertwined with that of the much more valuable gemstone, jacinth (a brownish-red variety of zircon), which was one of the original stones in Aaron’s breastplate. Over time, the colorless and blue varieties of zircon gained prominence for their brilliance, leading to its adoption as a birthstone.
The addition of tanzanite in 2002 represents the most recent major update to the birthstone list. This decision highlights how birthstones can evolve with new gemological discoveries. Tanzanite was only discovered in the late 20th century and quickly captivated the market with its extraordinary color and rarity. Its inclusion formally recognized a new, highly desirable gem in the modern birthstone canon.
Blue topaz, while not a traditional December stone in the same ancient sense, has become a staple due to its durability, affordability, and beautiful blue hues. The exact historical origin of blue topaz is unknown, as the stone has been found throughout history, often confused with other blue gems like sapphire. Its rise as a December birthstone is a modern phenomenon, driven by its availability and practical qualities for jewelry.
Beyond these four, historical sources list a variety of other stones that have been associated with December. The old Tibetan calendar assigned onyx as the December birthstone. Bloodstone (heliotrope) was a traditional birthstone for December from as far back as the 15th century. Ruby was the ancient birthstone for December in the old Arabic, Hebrew, Italian, Roman, and Indian (Ayurvedic) calendars. Chrysoprase held the title in the old Russian calendar, and lapis lazuli was a traditional stone that was later replaced by zircon. Cat’s eye is listed as the Indian birthstone for December. This extensive list underscores the rich and varied history of gemstone attribution for the final month of the year. The modern focus on the four blue gems simplifies this complex history into a more cohesive and marketable collection.
Geological Formation and Global Sources
Each of the four December birthstones forms under distinct geological conditions and is sourced from specific regions around the world, giving each stone a unique terrestrial story.
Turquoise is an opaque mineral that forms in arid regions where acidic, copper-rich groundwater percolates through rocks containing aluminum and phosphorus. Over thousands of years, this process creates deposits of turquoise, often accompanied by a "matrix" of host rock that can create intricate web-like patterns. The most significant sources include the Southwestern United States (particularly Arizona and New Mexico), Iran, Egypt, China, Mexico, and parts of Central Asia and Africa. The stone’s color can range from sky blue to apple green, influenced by the specific mineral content of the host rock and groundwater.
Zircon is a mineral belonging to the nesosilicates group, with a chemical formula of ZrSiO₄. It forms in the cooling of magma, particularly in igneous and metamorphic rocks. It is one of the oldest minerals on Earth, with some crystals dating back billions of years. While zircon is found worldwide, gem-quality material comes from specific localities. Notable sources include Sri Lanka, Australia, Myanmar, Norway, and parts of Africa. The blue variety, which is most relevant for December, is often heat-treated to achieve its vivid color, as most natural blue zircon is rare.
Tanzanite is a variety of the mineral zoisite. Its formation is remarkably specific. It is found in only one place on Earth: a tiny, four-square-kilometer mining area near Mount Kilimanjaro in Tanzania, East Africa. This geographic exclusivity is the primary reason for its rarity and high value. The gem is formed by a unique geological process involving the intense heat and pressure from tectonic activity that transformed zoisite into the vibrant blue-violet crystals we know today. The stone’s color is often described as trichroic, showing blue, violet, and burgundy hues depending on the viewing angle.
Blue topaz is a silicate mineral of aluminum and fluorine with the formula Al₂SiO₄(F,OH)₂. It crystallizes in igneous rocks, particularly in pegmatites and gas pockets in rhyolite. While topaz occurs in many colors, the vibrant blue shades that are popular for jewelry are almost always the result of irradiation and heat treatment applied to colorless or pale yellow natural topaz. Major sources of topaz include Sri Lanka, Brazil, Mexico, Nigeria, and the United States. The U.S. state of Texas even designates blue topaz as its official state gem.
Gemological Properties: A Scientific Profile
Understanding the physical and chemical properties of these gems is crucial for jewelers, collectors, and buyers, as it directly impacts their durability, care, and value.
Turquoise is an opaque phosphate mineral (hydrated copper aluminum phosphate). Its hardness on the Mohs scale is relatively low, typically ranging from 5 to 6. This makes it susceptible to scratching and requires careful handling. Its low hardness is compensated by its cultural and historical value. The stone’s color stability can be affected by chemicals, heat, and prolonged exposure to light, so proper care is essential.
Zircon is one of the hardest natural gemstones, with a Mohs hardness of 6.5 to 7.5. It has a high refractive index, giving it exceptional brilliance and fire, often compared to that of a diamond. However, zircon is also known for its brittleness and can be prone to chipping if struck, so protective settings are recommended for jewelry. It is a durable stone but requires more careful handling than other gems of similar hardness.
Tanzanite has a Mohs hardness of 6.5 to 7, making it relatively durable for jewelry, but it is more susceptible to chipping than harder stones like sapphire or diamond due to its cleavage. Its most distinctive property is its trichroism—the ability to display three different colors (blue, violet, and burgundy) from different crystal directions. This characteristic is a key identifier for the gem and is carefully considered during cutting to maximize its visual appeal.
Blue topaz is the most durable of the four December birthstones for everyday wear, with a Mohs hardness of 8. This makes it highly resistant to scratching and suitable for rings, bracelets, and other jewelry that may encounter daily abrasion. Its transparency and clarity allow for brilliant cuts that maximize light return. Like zircon, it has a high refractive index, contributing to its sparkle.
The following table summarizes the key gemological properties of the four December birthstones, based on the provided sources:
| Gemstone | Chemical Family | Mohs Hardness | Key Optical Property | Primary Color |
|---|---|---|---|---|
| Turquoise | Phosphate | 5 - 6 | Opaque | Blue to Green |
| Zircon | Nesosilicate | 6.5 - 7.5 | High Refractive Index (Brilliance) | Blue (treated) |
| Tanzanite | Zoisite (Sorosilicate) | 6.5 - 7 | Trichroism (Blue/Violet/Burgundy) | Blue-Violet |
| Blue Topaz | Silicate (Fluoride) | 8 | High Refractive Index (Brilliance) | Blue |
Symbolism and Metaphysical Beliefs Across Cultures
Beyond their physical beauty, all four December birthstones are steeped in symbolism and metaphysical lore, with each culture attributing unique powers and meanings to these gems.
Turquoise is perhaps the most symbolically rich of the group. Historically, it was considered a protective stone, believed to safeguard the wearer from harm, including falls and negative energy. Ancient royalty, such as King Tutankhamun, were buried with turquoise, believing it offered protection in the afterlife. In modern metaphysical beliefs, turquoise is associated with wisdom, tranquility, and friendship. It is also thought to promote mental clarity and emotional balance.
Zircon is believed to enhance spiritual strength and provide protection. Some traditions hold that zircon can promote prosperity and honor, while its brilliant sparkle is said to inspire wisdom and a sense of discipline. It is often considered a stone of purity and clarity.
Tanzanite, as a newer gem, has developed a modern mythology quickly. It is associated with transformation and spiritual awakening. Believers claim it can heighten awareness, expand perspective, and free a person from negativity. Its striking color is said to bridge the physical and spiritual realms, encouraging a higher consciousness and a sense of destiny.
Blue topaz is linked to communication, calm, and love. It is believed to enhance spiritual connection and promote a sense of peace and relaxation. In some beliefs, it is thought to aid in expressing one’s thoughts and feelings clearly and compassionately.
The collective symbolism of the December stones often revolves around themes of protection, wisdom, and emotional balance. The prevalence of blue tones across the group reinforces associations with calm, serenity, and communication. While these metaphysical beliefs are not scientifically proven, they form an integral part of the cultural heritage and personal significance attached to these gemstones.
Care and Cleaning: Preserving Your December Gems
The varying physical properties of the four December birthstones necessitate different care regimens to ensure their longevity and beauty.
Turquoise, with its relatively low hardness and porosity, requires the most care. It should be protected from chemicals, including cosmetics, perfumes, and cleaning agents, which can cause discoloration or damage. Cleaning should be done with a soft, dry cloth. Avoid ultrasonic cleaners and steam cleaning, as these can crack the stone or damage its porous surface. It is best to store turquoise jewelry separately to prevent scratching by harder gems.
Zircon is durable but brittle. It can be cleaned with warm water, mild soap, and a soft brush. However, due to its susceptibility to chipping, it should not be subjected to ultrasonic cleaners. Sudden temperature changes can also cause fractures, so it is advisable to avoid extreme environments.
Tanzanite is also sensitive to sudden temperature changes and can be damaged by ultrasonic vibrations. The safest method for cleaning tanzanite jewelry is with warm, soapy water and a soft brush. Given its cleavage, it should be handled with care to avoid sharp blows. Protective settings are recommended for rings to prevent impact damage.
Blue topaz, being the hardest and most durable of the four, is relatively easy to care for. It can be cleaned with warm, soapy water and a soft brush. It is generally safe for ultrasonic cleaners, but it is always wise to check with a professional jeweler, especially if the stone is set in a delicate or antique piece. Its high hardness makes it resistant to everyday wear, but it can still be scratched by harder materials like diamond or corundum.
In summary, while all four December birthstones can be worn in jewelry, their care requirements differ significantly. Understanding these properties allows owners to enjoy their gems for a lifetime, preserving both their physical integrity and their symbolic value.
Conclusion
The month of December offers a unique and diverse selection of birthstones, each with a distinct identity rooted in geology, history, and culture. Turquoise stands as the ancient, opaque guardian, cherished for millennia for its protective qualities and calming blue-green hues. Zircon brings unmatched brilliance and a connection to the ancient earth, its durability and fire making it a timeless choice. Tanzanite, the modern marvel from a single valley in Tanzania, captivates with its rare trichroic beauty and spiritual symbolism. Finally, Blue Topaz provides an accessible, durable, and brilliantly blue option for everyday elegance. Together, these four gems reflect the cool, serene, and multifaceted nature of winter, offering December-born individuals a rich palette of choices that are as deep and varied as the history of birthstones itself.