December stands alone in the calendar as the only month officially associated with four distinct birthstones. This unique distinction offers those born in the final month of the year an exceptional variety of choices, each reflecting the cool, wintry palette of the season. The four recognized birthstones—Blue Topaz, Tanzanite, Turquoise, and Blue Zircon—all share a dominant blue coloration, evoking the icy skies and deep twilight blues characteristic of December. While their hues may range from sky blue to violet-blue, each gem possesses a unique history, geological origin, and set of gemological properties.
The tradition of birthstones has evolved significantly over time. Originally, the list was more restrictive, but as new gemstones were discovered and commercialized, the options expanded. The modern standardization began in 1912 with the National Association of Jewelers, with subsequent updates adding new stones to meet commercial demand and celebrate new discoveries. Tanzanite, for example, was the most recent addition in 2002. This article provides a detailed exploration of these four magnificent gemstones, examining their historical journeys, geological formations, gemological characteristics, and the symbolism that has made them cherished possessions for generations.
History and Lore
The association of gemstones with specific months is a practice with deep historical roots, believed to have originated in ancient Mesopotamia and later adopted by the Greeks and Romans. The December birthstone list, in particular, has undergone several transformations. Originally, the month was primarily associated with Turquoise and Zircon. However, throughout the 20th century, the list expanded to include Blue Topaz and, most recently, Tanzanite. This evolution reflects not only the changing nature of the birthstone tradition but also the growing appreciation for new gemstone discoveries and their appeal in the commercial jewelry market.
Turquoise carries one of the longest histories of any gemstone. It has been prized for thousands of years across numerous cultures, particularly in ancient Egypt, Persia, and the Americas. It was traditionally believed to offer protection, grounding, and good fortune to its wearer. Its name is derived from the French phrase pierre turquoise, meaning "Turkish stone," as the gem was first brought to Europe from Turkey via Persian trade routes. For centuries, it has been a symbol of wealth and status, often used in intricate inlay work in royal and ceremonial objects.
Zircon also has an ancient lineage. For much of history, the term "zircon" was often used interchangeably with "jacinth" and was highly valued for its brilliance and fire. In the Middle Ages, it was believed to promote honor and prosperity in the wearer and to induce restful sleep. It was also thought to possess the power to ward off evil spirits and protect travelers. Its long-standing presence in the jewelry world is a testament to its enduring beauty, even if it has sometimes been overshadowed by other, more famous blue gemstones.
The introduction of Blue Topaz into the December birthstone list marked a shift toward more modern and commercially available gems. While topaz itself has been known since antiquity, the specific blue variety became prominent later. Its addition to the list provided a more affordable and widely available blue gem option, particularly as treatment methods improved the consistency and intensity of its blue color. The exact reason for the large number of December birthstones is not definitively known, but it is widely believed that the expansion was intended to offer consumers a wider range of affordable options.
Tanzanite is the newest addition to the December family, having been added to the official list in 2002. Its discovery is a thoroughly modern story. Found in only one location on Earth—the Merelani Hills of northern Tanzania—this gemstone was introduced to the world in the late 1960s. Its rapid rise to prominence and inclusion as an official birthstone highlights the dynamic nature of the gem trade and the ability of a truly exceptional new discovery to capture the public's imagination. Its symbolism is often linked to transformation, new beginnings, and clarity of mind.
Geological Formation and Sources
The four December birthstones originate from vastly different geological processes and are sourced from specific regions around the globe, which contributes to their rarity and value.
Blue Topaz is a silicate mineral that forms in igneous rocks, particularly in the gas pockets of cooling magma. The crystals grow in cavities and veins within these rocks. Today, the primary sources for blue topaz are Sri Lanka, Brazil, Mexico, Nigeria, and the United States. Its abundance and widespread mining locations make it one of the more accessible blue gemstones on the market. In the United States, it holds the distinction of being the official state gem of Texas.
Tanzanite is a variety of the mineral zoisite and owes its existence to a unique and highly localized geological event. It is found exclusively in a small, four-square-kilometer mining area in the Merelani Hills of northern Tanzania, near the base of Mount Kilimanjaro. This extreme rarity—being mined in only one location in the world—is the primary reason for its high value and status as the most expensive of the four December stones. The gem is formed through a complex process of metamorphism, where heat and pressure from tectonic plate movement altered the existing zoisite crystals, imbuing them with their signature violet-blue hue.
Turquoise is an opaque, hydrous phosphate of copper and aluminum. It forms when water containing these minerals seeps through rock, depositing the minerals in veins and nodules. This process typically occurs in arid regions, where the evaporation of water leaves the mineral deposits behind. Major sources for turquoise include the United States (particularly Arizona and New Mexico), Iran, and China. The color of turquoise can vary significantly depending on the amount of copper (which creates blue) or iron (which creates green) present during its formation.
Blue Zircon is the oldest mineral on the list, with crystals dating back billions of years. It is a zirconium silicate that forms in igneous and metamorphic rocks. While zircon is found in many parts of the world, the gem-quality blue variety used in jewelry is primarily sourced from Cambodia, Sri Lanka, and Thailand. The blue color in most commercial zircon is the result of a heat treatment process applied to brownish zircon crystals, which transforms their color into the desirable blue shade.
Gemological Properties
Understanding the physical and chemical properties of these gemstones is crucial for jewelers and consumers alike, as these characteristics determine a stone's durability, appearance, and care requirements.
Color: All four gemstones are prized for their blue hues, though the specific shades differ. Blue Topaz ranges from a pale, sky blue to a deep, saturated "Swiss Blue" or "London Blue." Tanzanite is unique for its pleochroism, displaying different colors—blue, violet, and burgundy—from different crystal directions, though it is typically cut to show the dominant blue-violet. Turquoise is opaque and varies from a light, sky blue to a greenish-blue, often featuring a distinctive brown or black matrix (web-like patterns). Blue Zircon is known for its brilliant, clear, bright blue, which can sometimes rival the appearance of a diamond due to its high refractive index.
Hardness and Durability: Durability is a key factor for jewelry intended for everyday wear. - Blue Topaz is the most durable of the four, with a hardness of 8 on the Mohs scale. This makes it highly resistant to scratching and suitable for all types of jewelry. - Blue Zircon has a hardness of 7 to 7.5 on the Mohs scale, making it reasonably durable, though it can be brittle and susceptible to chipping if struck hard. - Tanzanite is significantly softer, with a hardness of 6 to 6.5 on the Mohs scale. It is considered a delicate gem and is more suitable for earrings and pendants than for rings that might experience daily impact. - Turquoise is the softest of the group, with a hardness of 5 to 6 on the Mohs scale. It is also porous and can be susceptible to cracking or discoloration from chemicals, lotions, and even skin oils, requiring careful handling.
The following table summarizes the key gemological properties of the four December birthstones:
| Gemstone | Chemical Composition | Mohs Hardness | Crystal System | Primary Source(s) |
|---|---|---|---|---|
| Blue Topaz | Al₂SiO₄(F,OH)₂ | 8 | Orthorhombic | Brazil, Sri Lanka, U.S. |
| Tanzanite | Ca₂Al₃(SiO₄)₃(OH) | 6 - 6.5 | Orthorhombic | Tanzania |
| Turquoise | CuAl₆(PO₄)₄(OH)₈·4H₂O | 5 - 6 | Triclinic (massive) | U.S., Iran, China |
| Blue Zircon | ZrSiO₄ | 7 - 7.5 | Tetragonal | Cambodia, Sri Lanka |
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, each of the December birthstones is rich in symbolism and is believed by many to possess unique metaphysical properties.
Turquoise is widely regarded as a stone of protection, healing, and good fortune. It is believed to act as a stabilizing force, promoting inner calm and tranquility. For centuries, it has been used as a talisman by warriors and travelers, thought to shield its wearer from harm and negative energy. It is also associated with wisdom, truth, and the ability to see the bigger picture in life.
Tanzanite is a relatively modern stone in terms of its symbolic meaning, but it has quickly been associated with transformation, intuition, and spiritual awakening. Its unique color is said to represent a bridge between the physical and spiritual worlds. Many believe it can aid in communication, promote a higher consciousness, and help its wearer navigate major life changes with clarity and purpose. It is often seen as a stone for those embarking on new chapters in their lives.
Blue Zircon is traditionally associated with clarity of thought, honor, and purity. It is believed to boost self-confidence and encourage prosperity and honor. In the realm of metaphysical beliefs, it is said to help its wearer connect with their higher self and to facilitate a deeper understanding of one's own wisdom. It is also thought to have a calming effect, helping to alleviate feelings of anxiety and stress.
Blue Topaz is linked to calmness, clarity, and emotional balance. It is often called the "stone of love and good fortune" and is believed to attract wealth and success. Its cool blue color is associated with the throat chakra, making it a popular stone for those seeking to improve communication and express themselves more clearly and honestly. It is also thought to soothe anger and promote forgiveness.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of any gemstone jewelry. The varying hardness and stability of the December birthstones require different maintenance approaches.
Blue Topaz: Due to its good hardness (8 on the Mohs scale) and lack of significant cleavage, Blue Topaz is relatively easy to care for. It can be safely cleaned using warm soapy water and a soft brush. Ultrasonic and steam cleaners are generally safe, but it is always wise to check for any fractures or inclusions first.
Blue Zircon: Although it has a respectable hardness, zircon is brittle and can be chipped by a hard blow. It is best to avoid ultrasonic cleaners and extreme temperature changes. The safest cleaning method is warm, soapy water with a soft brush. Store it carefully to prevent it from rubbing against harder gems.
Turquoise: This gem requires the most careful handling. It is porous and can be damaged by chemicals, cosmetics, and even skin oils. Avoid exposing turquoise to lotions, perfumes, or harsh cleaning agents. Clean it only with a soft, dry cloth; avoid soaking it in water or using any type of cleaner. Stabilized turquoise (treated with a resin) is more durable but should still be treated with care.
Tanzanite: As the softest and most delicate of the four, Tanzanite is prone to scratching and abrasion. It is not recommended for rings worn daily. To clean it, use warm, soapy water and a soft brush. Avoid ultrasonic cleaners and steam cleaners, as the heat and vibrations can damage the stone. Store it separately in a soft cloth or padded jewelry box to protect it from harder gems.
Conclusion
The four birthstones of December—Blue Topaz, Tanzanite, Turquoise, and Blue Zircon—offer an unparalleled selection for those born in this month. From the ancient protective lore of Turquoise to the modern, transformative symbolism of Tanzanite, each gem carries a rich narrative. Their geological origins span the globe, from the singular mines of Tanzania to the widespread deposits of Brazil and the United States. While they all share a connection to the cool blue of winter, their gemological properties vary widely, dictating different levels of durability and care. Whether chosen for its durability, rarity, color, or symbolic meaning, a December birthstone is a timeless and personal treasure that captures the unique spirit of the year's final month.