December is unique in the birthstone calendar, offering three distinct gemstones: Turquoise, Zircon, and Tanzanite. Each possesses a captivating blue hue, yet they differ dramatically in origin, composition, history, and durability. For individuals born on December 31st—or any day in December—these stones provide a spectrum of choices, from the ancient, opaque charm of turquoise to the brilliant fire of zircon and the modern, velvety blue of tanzanite. This article explores the geological formation, gemological properties, historical significance, and practical care considerations for these three remarkable December birthstones, drawing exclusively from authoritative gemological sources.
History and Lore
The historical journey of these birthstones spans millennia and continents, reflecting diverse cultural values and uses.
Turquoise boasts one of the longest histories as a gemstone. Evidence indicates that Native Americans in the Southwestern United States utilized turquoise over 2,000 years ago. Ancient artists in this region crafted beads, pendants, intricate inlay work, and small sculptures from the stone, integrating it deeply into their cultural and artistic traditions. This historical significance persists today, as turquoise remains an important part of Southwestern culture. Its appeal is not limited to the Americas; it has been a valued gemstone globally for thousands of years, prized for its distinctive blue to blue-green to yellowish-green coloration.
Zircon is another ancient gem with a notable historical profile. While the provided sources do not detail its specific ancient uses, they emphasize its enduring appeal as a bright gem with high luster and a colorful fire comparable to diamond. This visual similarity to diamond has likely contributed to its long-standing presence in jewelry. The sources do not specify a particular ancient civilization that first used zircon, but its properties suggest it has been admired for its brilliance for a considerable period.
Tanzanite, in contrast, is a newcomer to the gemstone world. Unlike the ancient turquoise and zircon, tanzanite does not have a documented history spanning thousands of years in the provided sources. Its addition to the modern birthstone list is a recent event. The American Gem Trade Association added tanzanite as a December birthstone, marking the first change to the official list in 50 years. This addition highlights the evolving nature of birthstone charts and the introduction of new, visually striking gems to the market. Its history is therefore defined by its discovery in the 20th century and its swift rise to prominence in the gem and jewelry industry.
Geological Formation and Sources
Understanding where these stones come from provides insight into their rarity and value.
Turquoise is an opaque mineral formed in arid regions where acidic, copper-rich groundwater interacts with rocks containing aluminum and phosphorus. The provided sources confirm that turquoise is mined around the world. While specific mining locations are not listed in the chunks, the text notes its historical use in the Southwestern United States, implying significant deposits in that region. The gem's formation is geological, not biological, and it is mined from the earth.
Zircon is a mineral formed in igneous and metamorphic rocks. The sources state that zircon is mined around the world, though they do not specify primary mining countries. Its formation is tied to specific geological conditions where zirconium silicate crystallizes. The mention of its high luster and fire suggests it is mined in locations that yield gem-quality crystals suitable for faceting.
Tanzanite is also mined globally, according to the sources. The specific geological formation of tanzanite is not detailed in the provided chunks. However, its identification as a distinct gemstone with a unique blue color indicates it forms under specific mineralogical conditions. The sources confirm its status as a mined gemstone, contributing to the global supply of blue gemstones for December birthdays.
Gemological Properties
The physical and optical properties of these birthstones dictate their durability, appearance, and care requirements.
Composition and Hardness
Turquoise is a phosphate mineral (chemical composition not specified in sources), while zircon and tanzanite are silicate minerals. Hardness is a critical factor for gemstone durability. The Mohs scale, a standard measure of scratch resistance, is referenced in the sources for some gems.
- Turquoise is explicitly noted to have a low hardness, making it easily scratched. This property classifies it as a relatively soft gemstone, requiring careful handling.
- Zircon is not given a specific hardness rating in the provided chunks, but it is described as a "bright gem with high luster." In general gemology, zircon is known for its hardness (around 6.5-7.5 on the Mohs scale), but since this is not stated in the sources, we cannot confirm it here. The sources do mention that zircon is "prone to breakage," which may relate to its cleavage properties.
- Tanzanite is noted to have perfect cleavage and will break easily. This property indicates that tanzanite is fragile and susceptible to damage from impact or pressure. The sources do not provide a specific Mohs hardness for tanzanite, but the mention of perfect cleavage is a significant gemological warning.
Color and Clarity
Color is the most defining characteristic for these December stones.
- Turquoise ranges from blue to blue-green to yellowish green. The most preferred color is bright blue. As an opaque gemstone, clarity is not a grading factor in the same way it is for transparent stones. Its value is primarily determined by its color and matrix patterns.
- Zircon is described as a "bright gem" that produces a colorful fire similar to diamond. This "fire" refers to its high dispersion, which splits white light into spectral colors. The sources do not specify the color range of zircon, but its fire is a key property.
- Tanzanite is part of the trio of December birthstones that "all have their own unique take on the color blue." Its specific hue is not detailed beyond this, but it is known in the gem trade for its vivid blue-to-violet hues.
Cut and Form
The gem's physical properties influence how it is cut and set.
- Turquoise, being opaque, is typically cut into cabochon shapes. The sources note that it is often cut in freeform shapes to maximize the use of the rough material, rather than being cut into standardized calibrated sizes. This approach respects the natural form of the turquoise nugget or slab.
- Zircon and Tanzanite, being transparent to translucent, are typically faceted to enhance their brilliance and fire. The sources do not specify common cuts for these gems, but their properties suggest faceting is standard.
Comparison of Key Properties
The following table summarizes the gemological properties of the three December birthstones as described in the provided sources.
| Property | Turquoise | Zircon | Tanzanite |
|---|---|---|---|
| Color | Blue, blue-green, yellowish-green | Bright, with colorful fire (dispersion) | Unique shade of blue |
| Clarity/Transparency | Opaque | Bright gem (likely transparent) | Not specified, but known for transparency |
| Hardness (Mohs) | Low (easily scratched) | Not specified, but "prone to breakage" | Not specified, but has perfect cleavage |
| Durability Concerns | Low hardness, scratches easily | Prone to breakage | Perfect cleavage, breaks easily |
| Typical Cut | Cabochon, often freeform | Faceted (implied) | Faceted (implied) |
| Mining Source | Mined around the world | Mined around the world | Mined around the world |
Symbolism and Metaphysical Beliefs
The sources provide limited information on symbolism and metaphysical beliefs, focusing more on historical and gemological facts. However, some cultural associations are mentioned.
- Turquoise is deeply embedded in Southwestern culture, where it has been used for over two millennia. Its importance is cultural and artistic, symbolizing heritage and tradition in that region. The sources do not attribute specific metaphysical properties like healing or luck to turquoise.
- Zircon and Tanzanite are described in terms of their visual appeal and their status as birthstones. The sources do not mention any symbolic meanings, historical lore, or metaphysical beliefs associated with these two stones. The focus is on their gemological characteristics and their inclusion in the modern birthstone chart.
The provided materials emphasize the evolution of the birthstone list, noting that tanzanite was added as a recent modern addition, and zircon has been a December stone for some time. This evolution is driven by market availability, consumer preference, and the introduction of new gem discoveries, rather than by traditional symbolism.
Care and Cleaning
The durability of each gemstone dictates specific care instructions to preserve its beauty and integrity.
Turquoise requires careful handling due to its low hardness. It is easily scratched by harder materials, including dust and other gemstones. Cleaning should be done with a soft, damp cloth, avoiding harsh chemicals, ultrasonic cleaners, and steam. It should be stored separately from other jewelry to prevent scratching. Its porous nature can also make it susceptible to absorbing oils and chemicals, which may alter its color over time.
Zircon is noted to be prone to breakage. While not specified in the sources, this property suggests it may have cleavage or be brittle. Care should be taken to avoid knocks and impacts. Cleaning with warm, soapy water and a soft brush is generally safe, but ultrasonic and steam cleaners should be avoided unless the stone is known to be stable. Given its brilliance, it is often set in protective jewelry styles.
Tanzanite has perfect cleavage, making it exceptionally fragile. It can split easily along its cleavage planes if struck with force. This property makes it unsuitable for rings or bracelets that are subject to daily wear and impact. It is best set in pendants or earrings. Cleaning should be gentle: use warm, soapy water and a soft brush, and avoid any mechanical or thermal shocks. Never use ultrasonic or steam cleaners on tanzanite, as the vibrations and heat can cause immediate damage.
Conclusion
The three December birthstones—Turquoise, Zircon, and Tanzanite—offer a diverse palette of blue hues and distinct characteristics. Turquoise stands out for its ancient history, opaque beauty, and cultural significance in the Southwestern United States, though its low hardness requires careful maintenance. Zircon is celebrated for its brilliant fire and high luster, reminiscent of diamond, but it is prone to breakage. Tanzanite represents modernity, added to the birthstone list recently, and is prized for its unique blue color, though it is the most fragile of the three due to its perfect cleavage. For those born in December, the choice among these stones involves balancing personal preference for color and style with practical considerations of durability and care. Each stone carries its own legacy, from ancient artifacts to modern discoveries, making them meaningful and beautiful options for birthstone jewelry.