For those born in the final month of the year, the selection of birthstones is as varied and vibrant as a winter twilight. December is uniquely endowed with four official birthstones: Turquoise, Tanzanite, Blue Zircon, and Blue Topaz. Each of these gems possesses a distinct geological origin, a rich tapestry of history, and a set of gemological properties that make it a prized possession. While they share a dominant blue hue that reflects the cool tones of the season, their individual stories range from ancient royalty to modern discovery. This guide delves into the science, lore, and practical considerations of each of December's four magnificent blue gemstones, providing an expert resource for enthusiasts, collectors, and anyone seeking to understand the legacy of these captivating stones.
A Tradition of Blue: The History and Evolution of December's Birthstones
The concept of a specific birthstone for each month has evolved over centuries, rooted in ancient traditions. The practice is often linked to the Breastplate of Aaron, a ceremonial garment described in the Book of Exodus, which was set with twelve different gemstones. However, the modern list of birthstones is a more recent development, standardized for commercial and cultural consistency.
Turquoise: The Ancient Foundation
Turquoise stands as the oldest and most traditional birthstone for December. Its history spans thousands of years, with evidence of its use and admiration by ancient civilizations across the globe. This gemstone was a favorite of Egyptian pharaohs and Persian royalty. The name itself offers a clue to its journey into Western consciousness; "Turquoise" is derived from the French phrase pierre turquoise, meaning "stone of Turkey." This name was given because the gem was first brought to Europe from Turkish bazaars. For millennia, this opaque, sky-to-greenish-blue stone has been synonymous with protection, wisdom, and good fortune.
The Modern Additions to the December Family
While Turquoise has ancient roots, the other three December stones are relatively new additions to the official list, added to provide more options and reflect new discoveries. The standardization of birthstones began in 1912 when the National Association of Jewelers sought to create a consistent list for the American market. This list has been updated several times since. In 1952, the Jewelry Council of America added Blue Zircon to December's offerings. Decades later, in 2002, the American Gem Trade Association (AGTA) added the newly popular Tanzanite. The fourth stone, Blue Topaz, while not always listed on the most traditional charts, is widely recognized as a modern alternative or primary birthstone for the month, celebrated for its brilliant blue color and durability. Some sources suggest that the expansion of the December list, which now boasts the most options of any month, was a deliberate effort to provide consumers with a wider range of choices, including more affordable alternatives.
Geological Formation and Mining Locations
Each of the four December birthstones forms under unique geological conditions and is sourced from specific regions around the world, making their origins a key part of their identity.
Turquoise: The Mineral of the Arid Lands
Turquoise is a secondary mineral that forms when water containing copper and aluminum seeps through pre-existing rock. This process occurs in arid regions, where the evaporation of groundwater concentrates these minerals into solid, opaque veins. The distinctive color, ranging from sky blue to apple green, is primarily due to the presence of copper. The dark, web-like patterns often seen within the stone are known as matrix, which is the remnants of the host rock in which the turquoise formed.
Significant sources for turquoise include the southwestern United States (notably Arizona's Sleeping Beauty Mine), Iran (home to the highly prized Persian turquoise), Egypt, Mexico, China, and parts of Central Asia and Africa. Persian turquoise is particularly celebrated for its vivid, evenly saturated sky-blue color and its characteristically minimal to nonexistent matrix.
Tanzanite: The Singular Wonder
Tanzanite is the newest member of the December family, discovered less than 60 years ago. Its geological story is exceptionally rare. It is found in only one location on Earth: a small, postage-stamp-sized mining area in the Merelani Hills of northern Tanzania, near the majestic Mount Kilimanjaro. This extreme rarity is a major factor in its value. Tanzanite is a variety of the mineral zoisite and is almost always heat-treated to achieve its stable, vibrant blue-to-violet hue. The heat treatment is a standard industry practice that enhances the stone's natural color.
Blue Zircon: The Ancient Mineral
Zircon is the oldest known mineral on Earth, with samples from Australia dating back an astonishing 4.4 billion years. It is a common mineral found in many types of rock, but gem-quality zircon is much rarer. The blue variety, which is the birthstone for December, is most often created by heat-treating brown zircon crystals. This process can produce a brilliant blue that is highly sought after. While zircon is found in many locations globally, including Sri Lanka, Cambodia, and Australia, the heat-treated blue stones are a staple of the gem market.
Blue Topaz: The Durable Gem
Blue topaz is a silicate mineral that forms in igneous rocks, specifically in pegmatites and hydrothermal veins. While natural blue topaz does occur, most of the vibrant, deep blue topaz seen in jewelry today is the result of irradiation and heat treatment of colorless or pale topaz. This process is stable and produces a beautiful, consistent color. Major sources for topaz include Sri Lanka, Brazil, Mexico, Nigeria, and the United States. In fact, blue topaz is the official state gem of Texas, reflecting its significance in American gemology.
Gemological Properties: A Scientific Comparison
Understanding the physical and chemical properties of these gemstones is crucial for both jewelers and consumers, as it dictates their durability, care requirements, and overall value.
| Gemstone | Chemical Composition | Hardness (Mohs Scale) | Luster | Key Characteristics |
|---|---|---|---|---|
| Turquoise | Hydrated phosphate of copper and aluminum | 5 - 6 | Waxy to subvitreous | Opaque, often contains matrix (host rock remnants). |
| Tanzanite | Calcium aluminum hydroxyl sorosilicate | 6 - 7 | Vitreous | Strong pleochroism (displays blue, violet, and burgundy from different angles). |
| Blue Zircon | Zirconium silicate | 6.5 - 7.5 | Adamantine (brilliant) | High refractive index and dispersion, giving it exceptional brilliance and fire. |
| Blue Topaz | Aluminum fluoro-hydroxy silicate | 8 | Vitreous | Excellent durability, often treated to achieve deep blue color. |
Turquoise is an opaque stone with a hardness of 5 to 6 on the Mohs scale, making it relatively soft and susceptible to scratches. It has a characteristic waxy luster.
Tanzanite has a hardness of 6 to 7, making it moderately durable but sensitive to sudden temperature changes and blows. Its most famous property is pleochroism, where the stone shows different colors—typically blue, violet, and reddish-brown—depending on the viewing angle. Gem cutters must orient the stone carefully to display its most desirable blue-violet hue.
Blue Zircon is known for its exceptional brilliance and fire (the dispersion of light into spectral colors). With a hardness of 6.5 to 7.5, it is reasonably durable for most jewelry applications, though it can be brittle. Its high refractive index gives it a sparkle that rivals diamond.
Blue Topaz is the hardest and most durable of the four, with a Mohs hardness of 8. This makes it an excellent choice for rings and other jewelry worn daily. It has a vitreous (glass-like) luster and excellent clarity, often appearing transparent and eye-clean.
Symbolism, Lore, and Metaphysical Beliefs
Across cultures and centuries, these blue stones have been imbued with powerful meanings and attributed with special abilities.
Turquoise is perhaps the most storied of the four. It has long been considered a sacred stone, a powerful protector against harm. Ancient warriors would attach turquoise to their weapons and horse trappings, believing it would ensure a safe journey. It was also thought to protect the wearer from falls, particularly for horseback riders. Beyond physical protection, turquoise is associated with wisdom, tranquility, friendship, and good fortune. Its color is believed to mirror the heavens, bringing peace and clarity to the mind.
Tanzanite, as a modern discovery, has a more recent metaphysical history. It is often associated with transformation, spiritual awakening, and a higher consciousness. Its unique pleochroic nature is sometimes seen as a symbol of seeing the world from multiple perspectives. It is believed to promote a calm, meditative state and to help its wearer connect with their true purpose.
Blue Zircon in the Middle Ages was a symbol of wisdom, honor, and restful sleep. It was believed to ward off evil spirits and promote prosperity. Its brilliant sparkle was thought to bring light and clarity to the wearer's life.
Blue Topaz is associated with love, affection, and good fortune. It is believed to have a calming and soothing energy, promoting clear communication and emotional balance. Its cool blue hue is linked to the throat chakra, making it a popular stone for those seeking to express themselves more truthfully and effectively.
Care and Cleaning: Preserving Your December Gem
Proper care is essential to maintain the beauty and longevity of any gemstone. The varying hardness and structural integrity of the December birthstones demand specific attention.
Turquoise: Due to its porosity and relative softness, turquoise requires gentle handling. It is susceptible to cracking or discoloration from chemicals, cosmetics, and even skin oils. Clean it with warm, soapy water and a soft brush. Avoid ultrasonic cleaners, steam cleaners, and harsh chemicals. It is wise to store turquoise separately to prevent it from being scratched by harder stones.
Tanzanite: With a hardness of 6-7, tanzanite is moderately durable but should be protected from sharp blows and extreme temperature changes. It is best cleaned with warm, soapy water and a soft cloth. As with turquoise, avoid ultrasonic and steam cleaners, as vibrations and heat can damage the stone.
Blue Zircon: Although it has a good hardness, zircon can be brittle and prone to chipping if knocked hard. It is generally safe to clean with warm, soapy water and a soft brush. While it can often withstand an ultrasonic cleaner, it is best to use caution, especially if the stone has been subjected to heat treatment. Steam cleaning is not recommended.
Blue Topaz: As the hardest of the group, blue topaz is quite durable and can be cleaned with standard methods. Warm, soapy water and a soft brush are perfect for regular cleaning. Ultrasonic cleaners are generally safe, but steam cleaning should be avoided as it can potentially damage the stone, especially if it has been fracture-filled (though most commercial blue topaz is not). It is also important to note that topaz can be damaged by sudden temperature changes.
Conclusion
December's birthstones offer a remarkable spectrum of blue, from the opaque, earthy tones of ancient turquoise to the electric, violet-tinged brilliance of modern tanzanite. Each of the four gems—Turquoise, Tanzanite, Blue Zircon, and Blue Topaz—presents a unique combination of geological history, gemological character, and cultural significance. Whether one is drawn to the millennia-old protective lore of turquoise, the singular geographic origin of tanzanite, the ancient sparkle of zircon, or the durable beauty of topaz, those born in December have an unparalleled choice of stones that are as deep and captivating as the winter sky.