For those born in the final month of the year, the birthstone selection is uniquely abundant and visually cohesive. December is distinguished by not one, but three primary birthstones: Tanzanite, Turquoise, and Zircon. A fourth gemstone, Blue Topaz, is also frequently included in modern lists, creating a "blue trio" that reflects the cool, wintry palette of the month. These gemstones, ranging from the sky-blue of turquoise to the violet-blue of tanzanite, share a common theme of wisdom, protection, and spiritual growth. This comprehensive guide explores the history, geological origins, gemological properties, and cultural significance of these remarkable stones.
The journey of December's birthstones is one of evolution. While early historical lists designated ruby for December, the modern selection has been shaped by commercial availability, new discoveries, and changing tastes. The earliest formalized list from Tiffany & Co. in 1870 designated turquoise. This was followed by the 1912 standard from the National Association of Jewellers, which named turquoise as the primary stone and lapis lazuli as an alternative. Zircon was added in 1952, and the most recent addition, Tanzanite, was officially recognized in 2002. This history of adaptation makes December's collection one of the most dynamic in the birthstone calendar.
This article will delve into the individual stories of Tanzanite, Turquoise, and Zircon, examining their unique attributes, the locations from which they are sourced, and the meanings they have accumulated over centuries. We will also touch upon the role of Blue Topaz as a durable and popular modern alternative, providing a complete resource for gemstone enthusiasts, jewelry buyers, and students of gemology.
History and Lore
The historical narrative of December's birthstones is a blend of ancient tradition and modern discovery. Each stone carries a rich tapestry of cultural significance, from protective amulets of antiquity to symbols of transformation in the 21st century.
Turquoise: The Ancient Amulet
Turquoise is one of the oldest known gemstones, prized for thousands of years across numerous civilizations. Its distinctive color, ranging from robin's-egg blue to green-blue, has been a fixture in adornment and ritual. Ancient Egyptians adorned the burial masks of pharaohs with turquoise, believing it offered protection in the afterlife. The stone's name itself derives from the French "pierre turquoise," meaning "Turkish stone," reflecting its importation into Europe from mines in the Middle East through Turkish trade routes. In Native American cultures, particularly among the Navajo, Zuni, and Pueblo peoples, turquoise has been a cornerstone of jewelry and spiritual practice, used as a powerful talisman for protection, health, and good fortune. Its enduring legacy as a protective stone is a consistent thread throughout its long history.
Tanzanite: The Gem of a Generation
In stark contrast to turquoise's ancient lineage, Tanzanite is a thoroughly modern gem. It was discovered in 1967 in the Merelani Hills of Northern Tanzania, near the base of Mount Kilimanjaro. Its discovery is attributed to a Maasai tribesman, Ali Juuyawatu, who brought the blue crystals to the attention of a local prospector. The gem's official name, Tanzanite, was coined by Tiffany & Co., which recognized its potential and began featuring it prominently in 1968. The company marketed it as "the most beautiful blue gemstone to be discovered in 2,000 years." Due to its origin in a single, small area of the world, Tanzanite is considered rarer than diamond. Its status as a 20th-century discovery makes it the newest addition to the birthstone family, symbolizing new beginnings and modernity.
Zircon: The Colorless Beauty and Blue Sparkle
Zircon is a gemstone often confused with the synthetic cubic zirconia, but it is a naturally occurring mineral and one of the oldest on Earth, with some crystals dating back billions of years. Historically, colorless zircon was highly valued for its exceptional brilliance and fire, often serving as a diamond simulant in European crowns and jewelry. The blue variety of zircon, which is the most popular for December birthstones, is typically created through a heat-treatment process that transforms brownish zircon into a vibrant blue. This practice of enhancing zircon's color has been known for centuries, with its origins traced back to the Middle Ages. Its association with wisdom and clarity is rooted in its diamond-like appearance, which has long symbolized purity and strength.
Geological Formation and Sources
Understanding the geological origins of these gemstones reveals why some are so rare and others more widely available. The formation process and the specific locations of their mines are critical to their value and identity.
Tanzanite: A Singular Origin
Tanzanite is a variety of the mineral zoisite. Its formation is linked to a unique geological event. Approximately 585 million years ago, a massive tectonic plate shift and intense heat and pressure metamorphosed limestone, creating the conditions for zoisite crystals to form. The presence of trace amounts of vanadium is what imparts the gem's signature blue-violet hue. This specific set of geological circumstances occurred in only one location on the planet: a small, four-square-kilometer mining area in the Merelani Hills of Northern Tanzania. This extreme rarity and single-source origin are the primary drivers of its value and status.
Turquoise: A Hydrous Copper Mineral
Turquoise is not a crystalline mineral but a hydrous phosphate of copper and aluminum. It forms when water-rich solutions containing copper and aluminum seep through porous rock, depositing the mineral in nodules and veins. The presence of copper determines the blue color, while iron and chromium can create greenish tones. Historically, major sources included Persia (modern-day Iran), which produced the prized "robin's-egg blue" turquoise, and the American Southwest. Today, turquoise is mined in several countries, including the United States (Arizona, Nevada, New Mexico), China, Iran, and Mexico. The quality and color of turquoise are heavily dependent on the specific geology of the mining region.
Zircon: An Accessory Mineral
Zircon is an accessory mineral found in many igneous and metamorphic rocks. It is widely distributed and not confined to a single location. Major sources for zircon include Australia, which is a leading producer, as well as Thailand, Sri Lanka, Cambodia, Brazil, and Nigeria. The colorless and blue varieties used in jewelry are found in placer deposits, which are sedimentary deposits formed by the erosion of primary rock sources. The ability to heat-treat brown zircon to produce a stable blue color makes this gemstone more accessible and versatile for the jewelry market.
Gemological Properties
The physical and chemical characteristics of a gemstone determine its durability, appearance, and value. The December birthstones vary significantly in their properties.
| Gemstone | Mohs Hardness | Chemical Composition | Crystal System | Key Visual Identifier |
|---|---|---|---|---|
| Tanzanite | 6.5 - 7 | Ca2Al3(SiO4)3(OH) | Orthorhombic | Strong Trichroism (blue, violet, burgundy) |
| Turquoise | 5 - 6 | CuAl6(PO4)4(OH)8·4H2O | Triclinic (massive) | Cryptocrystalline, often veined or mottled |
| Zircon | 6.5 - 7.5 | ZrSiO4 | Tetragonal | High refractive index, excellent brilliance |
| Blue Topaz | 8 | Al2SiO4(F,OH)2 | Orthorhombic | Often found in large, clean crystals |
Tanzanite
Tanzanite registers between 6.5 and 7 on the Mohs scale of hardness, making it moderately durable but susceptible to scratches and impacts. It should be protected from hard wear. Its most remarkable gemological property is trichroism, the ability to display three different colors—blue, violet, and burgundy—when viewed from different crystallographic directions. This characteristic is so pronounced that gem cutters must orient the stone carefully to present the desirable blue-violet hue. The color of most tanzanite on the market is the result of a heat-treatment process applied to brownish zoisite, a treatment that is stable and widely accepted.
Turquoise
With a hardness of only 5 to 6 on the Mohs scale, turquoise is a relatively soft and porous gemstone. This makes it susceptible to damage from heat, chemicals, and even the oils from human skin, which can cause discoloration over time. It is often stabilized with resin or wax during the cutting and polishing process to improve its durability and luster. Turquoise is typically cut en cabochon (a smooth, rounded dome) to showcase its unique color and often features a "matrix"—a web-like pattern of the host rock (such as pyrite or limonite) that remains embedded in the stone.
Zircon
Zircon is a much harder and more durable gemstone, with a Mohs hardness ranging from 6.5 to 7.5. It possesses a very high refractive index, which gives it a brilliance and fire that can rival that of a diamond. This makes it an excellent choice for rings and other jewelry that will see regular wear. While colorless zircon exists, the blue zircon commonly used for December birthstones is produced by heating brown zircon at high temperatures. This treatment is permanent and results in a stable, attractive blue color.
Blue Topaz
Often included in the list of December stones, Blue Topaz is the most durable of the group, with a Mohs hardness of 8. It is a silicate mineral that forms in large, colorless crystals. The vibrant blue colors seen in jewelry, such as Swiss Blue and London Blue Topaz, are almost always the result of irradiation and heat treatment of the colorless original stone. Its hardness and the ability to produce large, clean stones make it a popular and affordable choice for statement jewelry.
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, these gemstones are deeply imbued with symbolic meaning and are believed by many to possess metaphysical properties.
- Tanzanite is often associated with transformation and new beginnings. Its discovery in the modern era links it to progress and a forward-looking perspective. It is believed to foster compassion, calmness, and a heightened spiritual awareness, helping the wearer navigate change with clarity and purpose.
- Turquoise is universally regarded as a stone of protection, grounding, and good fortune. It is said to absorb negative energy and promote a sense of inner peace and serenity. For centuries, it has been worn by warriors and travelers as a shield against harm and is believed to connect the wearer to the wisdom of the earth.
- Zircon is associated with clarity, wisdom, and honor. Its brilliant sparkle is thought to illuminate the path to self-realization and spiritual growth. It is also believed to promote restful sleep and attract prosperity and wealth. The colorless variety is linked to purity, while the blue variety enhances focus and mental clarity.
- Blue Topaz is linked to communication and creative expression. It is believed to soothe the mind, reduce stress, and inspire truth and forgiveness, making it a stone of peaceful communication.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of these gemstones, and the recommendations vary significantly based on their physical properties.
Tanzanite (Moderate Care): Due to its moderate hardness and cleavage tendency, Tanzanite should be handled with care. It is best cleaned with warm water, a mild soap, and a soft brush. Avoid ultrasonic cleaners and steam cleaning, as the vibrations and heat can cause fractures. Store it separately to prevent scratching by harder gems.
Turquoise (Delicate Care): As a porous and relatively soft stone, turquoise requires the most attention. It should be wiped clean with a soft, dry cloth. Avoid exposure to chemicals, including perfumes, lotions, and household cleaners, as well as prolonged sunlight, which can cause fading. Do not use ultrasonic cleaners or soak turquoise in water.
Zircon (Moderate Care): Zircon is relatively durable but can be brittle. Clean it with warm soapy water and a soft brush. While it can withstand an ultrasonic cleaner, it is best to avoid sudden temperature changes. Store it carefully, as it can be scratched by gems with higher hardness.
Blue Topaz (Easy Care): As the hardest of the December stones, blue topaz is quite durable and easy to care for. It can be safely cleaned in an ultrasonic cleaner and with warm soapy water. However, it is important to note that prolonged exposure to strong sunlight or extreme heat can cause the blue color to fade, so it should be stored away from direct light.
Conclusion
The birthstones of December—Tanzanite, Turquoise, and Zircon, with the occasional inclusion of Blue Topaz—offer a remarkable diversity of history, origin, and character united by a stunning blue palette. From the ancient protective amulet of turquoise to the modern rarity of tanzanite and the brilliant fire of zircon, each gem provides a unique connection to the natural world and human culture. Their journey through history, from early birthstone lists to their modern recognition, reflects a story of adaptation and discovery. For the December-born, these stones are more than just beautiful jewels; they are symbols of wisdom, protection, and transformation, each with a distinct story to tell and a legacy to be cherished.