For those born in the crisp, winter month of December, the birthstone selection is uniquely generous. Unlike many months with a single gem, December is traditionally represented by a trio of stunning blue gemstones: Tanzanite, Turquoise, and Zircon. Each of these stones shares a predominantly cool, blue color palette that evokes the icy skies and deep twilight blues of the season, yet each possesses its own distinct history, geological origin, gemological properties, and symbolic significance. Over time, this list has expanded in modern jewelry to include Blue Topaz, further enriching the choices available. This article provides a comprehensive exploration of these remarkable gemstones, delving into their formation, properties, historical lore, and care, drawing exclusively from authoritative gemological sources.
The collective identity of December's birthstones is one of wisdom, protection, and spiritual growth. From the ancient talisman of Turquoise to the rare, modern discovery of Tanzanite and the brilliant, diamond-like sparkle of Zircon, these gems offer a spectrum of beauty and meaning. Understanding their individual characteristics is essential for collectors, jewelry buyers, and anyone interested in the science and lore of gemstones. This guide will systematically examine each stone's journey from the earth to the jewelry box, providing the detailed knowledge necessary to appreciate and select these December treasures.
History and Lore: From Ancient Talismans to Modern Discoveries
The history of December's birthstones spans millennia, from some of the earliest known gemstones to one of the most recent additions to the gemological world. Turquoise stands as the oldest among the trio, with a documented history of use in jewelry and amulets exceeding 5,000 years. Its distinctive color, ranging from robin's-egg blue to green-blue, has been prized across numerous ancient civilizations. Historical records and archaeological finds show that Turquoise was treasured by ancient Egyptians, Persians, and Native American cultures as a powerful talisman for protection, prosperity, and healing. Its enduring legacy as a protective stone is deeply embedded in cultural traditions worldwide.
In contrast, Tanzanite represents a very modern chapter in gemstone history. This striking violet-blue gemstone was discovered only in 1967 in Tanzania, from which it derives its name. It is a variety of the mineral zoisite and was added to the birthstone list relatively recently. Its discovery in a small area near Mount Kilimanjaro immediately highlighted its rarity, as this is the only known source in the world. Tanzanite's introduction to the gem market and subsequent inclusion as a December birthstone mark it as one of the most significant gemological discoveries of the 20th century.
Zircon, the third traditional stone, occupies a historical middle ground. Valued since ancient times for its brilliance, it is often mistaken for diamond due to its exceptional fire and sparkle. While its history is long, it lacks the ancient, widespread cultural talismanic status of Turquoise or the singular, modern origin story of Tanzanite. Zircon has been consistently appreciated for its optical properties, serving as a durable and brilliant gem in jewelry for centuries.
The official list of December birthstones has evolved. Traditionally, Turquoise and Zircon were the recognized stones. The addition of Tanzanite in the 20th century expanded the choice. Notably, Blue Topaz has gained significant popularity in modern times, particularly in the U.S. market, and is now frequently considered a mainstream December birthstone, though it was a later addition. The Gemological Institute of America (GIA) lists Turquoise, Tanzanite, and Zircon as the primary December birthstones, acknowledging their varied blue-to-green and violet hues. This expansion offers consumers greater flexibility in price, durability, and style, all while maintaining the cool, wintry palette that defines the month.
Geological Formation and Sources
The origins of these gemstones are as diverse as their histories, ranging from ancient, widespread geological processes to a single, localized modern discovery.
Turquoise is a secondary mineral formed in arid regions where acidic, copper-rich water percolates through rocks containing aluminum and phosphorus. This process occurs over millions of years in the upper layers of the earth, creating the nodules and veins that are mined for gem-quality material. While turquoise deposits are found in several locations globally, including Iran (historically the source of the finest "Persian turquoise"), the southwestern United States (notably Arizona and New Mexico), and China, the sources do not specify particular mines or regions beyond the general locations mentioned. Its formation is inherently tied to specific geological conditions, making high-quality natural turquoise a relatively rare resource.
Tanzanite's geological story is unique and geographically confined. It is found exclusively in a small mining area near Mount Kilimanjaro in Tanzania, East Africa. This limited source is the reason it is considered one of the rarest gemstones in the world. The gem is a variety of zoisite, and its formation is linked to specific metamorphic processes in that region. The commercial mining of tanzanite is concentrated in this single area, making its supply finite and subject to the conditions of one specific location.
Zircon is a zirconium silicate mineral that forms in igneous and metamorphic rocks. It is a common accessory mineral found in many rock types worldwide, but gem-quality zircon is much rarer. Significant deposits for gem zircon are found in various locations, including Australia, Cambodia, Sri Lanka, and Vietnam. Unlike tanzanite, zircon is not limited to a single source, though high-quality, clear, richly colored zircon from specific localities is highly valued.
Blue Topaz, while not a traditional December birthstone, is included in modern lists. Its sources are not detailed in the provided materials, but it is important to note that naturally occurring blue topaz is exceedingly rare. The vibrant blue colors seen in jewelry (Sky Blue, Swiss Blue, London Blue) are almost always the result of irradiation and heat treatment of colorless or pale blue topaz. This treatment process is stable and accepted in the gem trade, making blue topaz an affordable and durable option for December birthstone jewelry.
Gemological Properties
Understanding the physical and chemical properties of these gemstones is crucial for their identification, valuation, and care. The following table summarizes the key gemological characteristics based on the provided sources.
| Gemstone | Mineral Family | Chemical Formula (General) | Typical Color Range | Hardness (Mohs Scale) | Key Optical Phenomena | Durability & Care Notes |
|---|---|---|---|---|---|---|
| Turquoise | Phosphate | Hydrated copper/aluminum phosphate | Robin's-egg blue to green-blue | 5 - 6 | Opaque to semi-translucent; can have a matrix (veining) | Relatively soft and porous. Avoid chemicals, high heat, and ultrasonic cleaners. Best for protected settings. |
| Tanzanite | Zoisite (Sorosilicate) | Ca₂Al₃(SiO₄)₃(OH) | Violet-blue, blue, purple, burgundy | 6 - 7 | Trichroism/Pleochroism: Shows different colors (blue, purple, burgundy) from different viewing angles. | Delicate. Prone to chipping and breaking. Requires protective settings. Sensitive to heat and sudden temperature changes. |
| Zircon | Zirconium Silicate | ZrSiO₄ | Colorless, blue, golden brown, green, red | 6.5 - 7.5 | High Refractive Index (1.92-1.98): Excellent brilliance and fire, rivaling diamond. Can be brittle. | Moderate hardness but brittle. Can fracture along cleavage planes. Best in protected settings like earrings or halo rings. |
| Blue Topaz (Modern) | Topaz (Silicate) | Al₂SiO₄(F,OH)₂ | Sky Blue, Swiss Blue, London Blue (treated) | 8 | Transparent, vitreous luster. Color is typically from irradiation/heat treatment. | Durable and suitable for everyday wear. Resistant to chemicals and heat. |
Turquoise is characterized by its hardness of 5 to 6 on the Mohs scale, making it one of the softer gemstones used in jewelry. It is often opaque and can contain a matrix or veining, which is part of its natural character. Its porosity requires careful handling.
Tanzanite has a hardness of 6 to 7, which is moderate but belied by its brittleness. Its most famous property is its trichroism (a form of pleochroism), where a single stone can display three different colors—typically blue, purple, and burgundy—depending on the crystallographic direction from which it is viewed. This phenomenon is responsible for its captivating color play. Tanzanite is also sensitive to heat; improper handling or exposure to high temperatures can damage or alter its color.
Zircon is notable for its exceptional brilliance and fire, attributed to its very high refractive index (1.92 to 1.98), which is higher than that of sapphire and even approaches diamond. This makes a well-cut zircon exceptionally sparkly. With a hardness of 6.5 to 7.5, it is more durable than turquoise or tanzanite but can be brittle, meaning it may chip or fracture if struck with force, particularly along its cleavage planes.
Blue Topaz, with a hardness of 8, is the most durable of the December gemstones. Its deep blue colors, such as London Blue, are achieved through a standard and stable process of irradiation followed by heat treatment. This durability makes it an excellent choice for rings and pieces intended for daily wear.
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, December's birthstones are rich in symbolism and metaphysical lore, each carrying a unique set of meanings that have been attributed to them over centuries or, in the case of tanzanite, more recently.
Turquoise is universally regarded as a stone of protection, strength, and healing. Its symbolism includes guarding against misfortune and accidents, encouraging honest communication, and representing loyalty in friendship and love. It is also believed to promote emotional balance and stability, acting as a steadying force during chaotic times. For many, turquoise is a grounding talisman that fosters a sense of calm and well-being.
Tanzanite, as a modern gemstone, has quickly accumulated its own symbolic significance. It is linked to transformation, spiritual growth, and new beginnings. Its striking color shift is seen as a metaphor for shifting perspectives and stepping into new chapters of life with clarity and curiosity. It is often associated with higher consciousness, intuition, and the awakening of psychic abilities, making it a favorite for those seeking personal evolution.
Zircon is known as a stone of balance, clarity, and prosperity. It is believed to sharpen focus, clear the mind of negativity, and strengthen intellectual growth. Its grounding energy promotes stability and security. In metaphysical traditions, zircon is also considered a protective stone that shields the wearer from harmful energies and attracts wealth and good fortune.
Blue Topaz, when included, is associated with calmness, clarity, and communication. Its soothing blue hues are thought to promote peacefulness, reduce stress, and enhance clear expression. It is often linked to the throat chakra, supporting truthful communication and emotional release.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of these gemstones, and their requirements vary significantly based on their physical properties.
Turquoise, due to its softness (Mohs 5-6) and porosity, demands the most careful handling. It should be protected from chemicals, including perfumes, lotions, and household cleaners, which can damage its surface and cause discoloration. It is also sensitive to high heat and should never be cleaned in an ultrasonic cleaner. The best method for cleaning turquoise is with a soft, damp cloth. It is best suited for jewelry pieces that are not subjected to daily knocks, such as pendants, earrings, or occasional-wear rings, preferably in protective settings.
Tanzanite (Mohs 6-7) is more durable than turquoise but is notoriously brittle. It is susceptible to chipping and breaking from impacts. Like turquoise, it is sensitive to heat and sudden temperature changes, which can cause internal stress and damage. Tanzanite should be set in protective jewelry, such as bezel settings or pieces where the stone is not exposed to lateral pressure. Cleaning should be done gently with warm water, mild soap, and a soft brush. Avoid ultrasonic and steam cleaners.
Zircon (Mohs 6.5-7.5) is relatively hard but has poor toughness due to its brittleness and cleavage. It can fracture if struck with force. It is stable under normal wearing conditions but should be protected from sharp blows. It is generally safe to clean with warm soapy water and a soft brush. However, due to its brittleness, it is often set in protective settings like halo rings or earrings where the edges are less likely to be impacted.
Blue Topaz (Mohs 8) is the most durable and low-maintenance of the group. It is resistant to chemicals, heat, and everyday wear. It can be safely cleaned in an ultrasonic cleaner and with warm soapy water, making it an excellent choice for rings and bracelets intended for daily use.
Conclusion
The December birthstones—Tanzanite, Turquoise, and Zircon—offer a remarkable diversity of beauty, history, and meaning within a unified blue palette. From the ancient, protective talisman of Turquoise to the rare, transformative Tanzanite and the brilliantly sparkling Zircon, each stone provides a unique connection to the natural world and human culture. The modern inclusion of Blue Topaz further expands the options, adding exceptional durability to the December selection. Understanding their geological origins, gemological properties, and specific care requirements allows enthusiasts and collectors to make informed choices. Whether selected for their symbolic significance, their stunning visual appeal, or their historical legacy, these gemstones remain enduring symbols of the wisdom, protection, and clarity associated with the winter month of December.