December is uniquely distinguished among all months by offering not one, but four official birthstones, each sharing a common thread of captivating blue coloration. This abundance provides those born in the final month of the year with a remarkable choice, allowing for personal preference in hue, durability, and symbolism. The four December birthstones are blue topaz, blue zircon, tanzanite, and turquoise. While their colors all evoke the cool tones of winter, each gemstone possesses a distinct geological origin, historical journey, and set of gemological properties. From the ancient tradition of turquoise to the modern discovery of tanzanite, the birthstones of December reflect a rich tapestry of geological and cultural history. This guide explores the origins, properties, symbolism, and care for each of these four blue gemstones, providing a detailed resource for gemstone enthusiasts, jewelry buyers, and students of gemology.
History and Lore: The Evolution of a Modern Tradition
The concept of birthstones has evolved significantly over centuries, culminating in the standardized list known today. The modern association of specific gemstones with each month was largely formalized in the early 20th century. In 1912, the National Association of Jewelers in the United States established an official list, combining historical customs with gemstones deemed practical for jewelry companies to sell. This list was updated in 1952 by the Jewelry Industry Council of America, which added blue zircon to December’s offerings. The most recent addition to the December birthstone family occurred in 2002, when tanzanite was officially included. The reasons for December having four birthstones are not definitively recorded, but some sources suggest it was to provide more affordable options to consumers, as birthstones can evolve with new gemstone discoveries and commercial offerings.
Each of the four gemstones carries its own profound history and lore. Turquoise stands as the oldest and most traditional December birthstone, treasured for thousands of years across various cultures. Its name is derived from the French pierre turquoise, meaning "Turkish stone," reflecting its historical trade route from Persia (modern-day Iran) to Europe. Persian turquoise, sourced from Iran’s ancient mines, is the most prized variety, celebrated for its vivid, evenly saturated sky-blue color and minimal matrix. This premium turquoise has been admired for centuries for its purity and remarkable hue. Another highly regarded variety is Sleeping Beauty Turquoise, renowned for its pure, robin’s-egg blue color and exceptionally low to absent matrix. Mined exclusively from the Sleeping Beauty Mine in Arizona before its closure, this turquoise is treasured for its smooth, uniform appearance and vibrant color.
In contrast, the other three December birthstones have much more recent histories in the gemstone market. Blue topaz’s exact historical origin is unknown, as it has been found throughout history, but its modern popularity as a birthstone is a relatively contemporary phenomenon. Blue zircon, while a natural gemstone for millennia, was only added to the official list in 1952. Its brilliant fire and diamond-like appearance have made it a valued, if somewhat delicate, alternative.
Tanzanite is the most recent addition and the most geologically unique of the four. It entered the gemstone market in 1967 and was initially mistaken for sapphire. Its unique multidimensional appearance, which displays shifting blue and violet hues, suggested something entirely new to gemologists, who soon identified it as a previously unknown variety of the mineral zoisite. Tiffany & Co., recognizing its market potential, named the stone after its country of origin, Tanzania, to promote consumer recognition. Its popularity soared, leading to its official inclusion as a December birthstone in 2002.
Geological Formation and Sources
The four December birthstones originate from vastly different geological environments and are mined in distinct regions of the world, which contributes to their rarity and value.
Turquoise is a secondary mineral formed in the near-surface environment where water containing copper, aluminum, and phosphorus percolates through pre-existing rock. The most historically significant source is Iran (Persia), which has supplied the world's finest turquoise for millennia. In the United States, Arizona has been a major producer, with the now-closed Sleeping Beauty Mine being a notable source for the prized robin's-egg blue variety. Turquoise is often found in nodules or veins within host rock, and its color and matrix (the veining of host rock) are key factors in its evaluation.
Blue Topaz is a silicate mineral composed of aluminum and fluorine. While topaz crystals can be found in various geological settings, including pegmatites and hydrothermal veins, the natural blue variety is relatively rare. Most of the blue topaz available in the commercial market today is produced by irradiating naturally colorless topaz. The exact historical origin of blue topaz is unknown, but today, it is mined in several countries, including Sri Lanka, Brazil, Mexico, Nigeria, and the United States. It is notably the official state gem of Texas.
Blue Zircon is a zirconium silicate (ZrSiO₄), a mineral that forms in igneous and metamorphic rocks. It is a common accessory mineral in many rock types but gem-quality crystals are less frequent. The sources for blue zircon are not specified in the provided materials, but its availability in the gemstone market is established. It is important to distinguish blue zircon from cubic zirconia, a synthetic diamond simulant; they are completely different materials.
Tanzanite is a variety of the mineral zoisite and is prized for its extreme rarity. It is mined exclusively in a very small area of Tanzania, near Mount Kilimanjaro. This specific geological setting, resulting from tectonic plate movement, is the only known source of tanzanite in the world. Its single-source origin makes it significantly rarer than diamonds, contributing to its status as the most valuable and expensive of the four December birthstones.
Gemological Properties
The physical and optical properties of these gemstones determine their durability, appearance, and suitability for different types of jewelry. The following table summarizes key gemological data for each December birthstone, based on the provided sources.
| Gemstone | Color & Varieties | Mohs Hardness | Chemical Composition & Notes |
|---|---|---|---|
| Turquoise | Blue to green; often opaque, sometimes with matrix | 5 – 6 | A secondary phosphate mineral; color can vary based on copper and iron content. |
| Tanzanite | Violet-blue to deep blue; pleochroic (shows blue and violet hues) | 6 – 7 | A variety of zoisite; known for its trichroic nature (shows three colors). |
| Blue Topaz | Sky Blue, Swiss Blue, London Blue | 8 | Silicate mineral (Al₂SiO₄(F,OH)₂); most commercial blue topaz is irradiated colorless topaz. |
| Blue Zircon | Brilliant blue (also available in other colors) | 6.5 – 7.5 | Zirconium silicate (ZrSiO₄); known for its exceptional brilliance and fire. |
Blue Topaz is the hardest and most durable of the December birthstones for everyday wear, ranking an 8 on the Mohs scale. However, it is described as having deep cleavage, making it somewhat delicate despite its hardness. Its color range spans from dark inky blues to lighter shades, with commercial varieties including London Blue (deep, inky blue), Swiss Blue (vibrant, medium light blue), and Sky Blue (light aqua). Its glass-like luster is notable.
Blue Zircon ranks up to 7.5 on the Mohs scale, making it fairly hard. However, it is brittle and can chip easily, which necessitates protective settings, especially for rings or frequently worn pieces. Its key gemological appeal is its exceptional brilliance and fire, often resembling diamonds.
Tanzanite has a hardness of 6 to 7 on the Mohs scale. Its most defining characteristic is its strong pleochroism, displaying different colors—typically blue and violet—when viewed from different angles. This property gives it a unique, multidimensional appearance that was initially mistaken for sapphire. Its color can range from a pale lavender to a deep, saturated blue-violet.
Turquoise is the softest of the group, with a hardness of only 5 to 6. It is typically opaque to semi-transparent, and its color can range from sky blue to green. The presence of matrix (veins of the host rock) is common, though highly prized varieties like Persian and Sleeping Beauty turquoise are known for their vibrant, even color with minimal to absent matrix. Its softness and porosity require careful handling.
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, each December birthstone carries a legacy of symbolic meaning and metaphysical belief, often rooted in centuries of cultural tradition.
Turquoise is overwhelmingly associated with protection, healing, and friendship. Ancient cultures, from the Egyptians to the Native American peoples of the Southwest, believed the stone offered spiritual protection and warding off evil. It is also linked to healing energies and is often given as a token of friendship and positive connection.
Tanzanite, as a modern discovery, has developed contemporary symbolic meanings. It is often associated with transformation, intuition, and spiritual growth. Its unique formation and recent entry into the gemstone lexicon make it a symbol of new beginnings and heightened perception.
Blue Topaz is symbolically linked to clarity, communication, and calmness. Its cool blue hues are thought to promote peacefulness and clear thought. In some belief systems, it is considered a stone of truth and forgiveness, aiding in the expression of one’s ideas and feelings.
Blue Zircon is traditionally associated with wisdom, prosperity, and good fortune. Its brilliant, diamond-like fire has led it to be seen as a stone that attracts success and abundance. It is also believed to promote mental clarity and spiritual grounding.
It is important to note that while these symbolic meanings are widely reported in gemological and cultural literature, they are part of historical and metaphysical traditions rather than scientific properties.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of any gemstone, and the specific properties of the December birthstones dictate their maintenance requirements.
Blue Topaz, with its hardness of 8, is quite durable and suitable for everyday jewelry. It can be cleaned with warm, soapy water and a soft cloth or brush. It can be stored with other gemstones without fear of scratching due to its hardness. However, its deep cleavage means it should be protected from sharp blows.
Blue Zircon requires more caution. While fairly hard, its brittleness makes it prone to chipping. It is not recommended for use in jewelry that will be worn during physical activities or exposed to harsh conditions. Cleaning should be gentle, using a soft cloth and warm, soapy water. Protective settings are strongly advised for rings.
Tanzanite, with a hardness of 6 to 7, is moderately durable but should be handled with care. It is not ideal for rings that are subject to daily knocks and bumps. Cleaning can be done with warm, soapy water and a soft brush. It should be stored separately to avoid scratches from harder stones.
Turquoise is the most delicate of the four, given its softness (5-6 Mohs) and often porous nature. It should be protected from chemicals, cosmetics, and prolonged exposure to sunlight or heat, which can cause discoloration. Cleaning should be done with a soft, dry cloth; avoid soaking it in water or using ultrasonic cleaners. It is best stored in a cool, dry place. Turquoise jewelry is best suited for occasional wear rather than constant, rough use.
Conclusion
The four December birthstones—blue topaz, blue zircon, tanzanite, and turquoise—offer a diverse and fascinating selection for those born in the final month of the year. From the ancient, protective traditions of turquoise to the modern rarity and transformative symbolism of tanzanite, each gemstone provides a unique narrative. Their shared blue color palette connects them to the winter season, yet their individual histories, geological origins, and physical properties set them apart. Blue topaz stands out for its durability and clarity, blue zircon for its diamond-like fire, tanzanite for its exclusive source and shifting hues, and turquoise for its timeless cultural significance and soft, organic beauty. Understanding these distinctions allows for an informed choice, whether for jewelry, collection, or study, and deepens the appreciation for the natural and cultural heritage embedded within each stone.