The month of December is uniquely associated with three distinct birthstones: turquoise, tanzanite, and zircon. Each gemstone offers a different interpretation of the color blue, ranging from the ancient, opaque sky-blue of turquoise to the vivid violet-blue of tanzanite and the bright, fiery brilliance of zircon. This trio provides a remarkable spectrum of choices for those born in the final month of the year, allowing for personal selection based on style, budget, and significance. The following article explores the history, geological origins, gemological properties, and cultural symbolism of these three December birthstones, drawing exclusively from authoritative gemological and historical sources.
History and Lore
The history of December's birthstones is a tapestry of ancient tradition and modern innovation. Turquoise, the oldest of the three, has been used as a gemstone for thousands of years. Archaeological evidence indicates that Native Americans in the Southwestern United States were utilizing turquoise over 2,000 years ago, creating beads, pendants, inlay work, and small sculptures. This deep historical connection has ensured turquoise remains an integral part of Southwestern culture to this day.
In contrast, tanzanite and zircon are relative newcomers to the birthstone list. The modern birthstone chart has evolved significantly over time. The National Association of Jewelers (now Jewelers of America) established the first official birthstone chart in the United States, creating a standardized list. The chart has undergone several major updates. The first significant revision added alexandrite to June, citrine to November, and pink tourmaline to October as alternative options. A pivotal moment for December's stones occurred when the American Gem Trade Association added tanzanite as a December birthstone, marking the first change to the list in 50 years. Zircon, while historically significant, was added to most birthstone lists more recently, in 1952.
The evolution of the birthstone chart reflects a blend of tradition and accessibility. Traditional British charts, for instance, include bloodstone for March and rock crystal for April as alternatives. In the United States today, people often draw freely from both traditional and modern lists, selecting stones that appeal to them personally. Some traditional gems, like turquoise, are also less expensive than their modern counterparts, contributing to their enduring popularity.
Geological Formation and Sources
The three December birthstones originate from vastly different geological environments and are mined in various locations around the world.
Turquoise is a blue to blue-green to yellowish green mineral. Its formation typically occurs in arid regions where acidic, copper-rich groundwater percolates through rocks containing aluminum and phosphorus minerals. The southwestern United States is a historically significant source, but turquoise is also mined in other parts of the world. As an opaque gemstone, turquoise is often cut into cabochon shapes, frequently freeform to maximize the yield from the rough material.
Tanzanite is a more recently discovered gemstone. While the provided sources do not specify its exact mining locations, they note that December birthstones are "mined around the world." The name itself suggests a geographic origin, and its addition to the birthstone list in 1952 coincides with its commercial emergence. Like turquoise, tanzanite is prized for its blue color, which can range from blue to violet-blue.
Zircon is a bright gem with high luster, and many specimens produce a colorful fire similar to that of a diamond. The sources indicate that zircon is mined globally. Its formation occurs in a variety of geological settings, often in igneous or metamorphic rocks. A key historical point is that the discovery of large deposits of topaz (another November birthstone) in Brazil greatly reduced the price of topaz, and most citrine also comes from Brazil. While this information pertains to November stones, it highlights the impact of major discoveries on the gem market. Zircon's own value has been influenced by its availability, and it is known for its brilliance.
Gemological Properties
Understanding the physical properties of these gemstones is crucial for both appreciation and care. The following table summarizes key gemological data for the three December birthstones, based on the provided sources.
| Month | Modern Birthstone | Color | Hardness (Mohs Scale) | Key Properties |
|---|---|---|---|---|
| December | Tanzanite | Blue/Purple | 6.5-7 | Prone to breakage; has perfect cleavage. |
| December | Turquoise | Blue to Blue Green | 2.5-4.5 | Low hardness; easily scratched; opaque. |
| December | Zircon | Bright, Fire | Not explicitly stated | High luster; colorful fire similar to diamond. |
Turquoise has a relatively low hardness, ranging from 2.5 to 4.5 on the Mohs scale. This makes it susceptible to scratching and requires careful handling. Its opacity means it is typically cut into cabochons rather than faceted gems. The most preferred color is bright blue.
Tanzanite has a hardness of 6.5 to 7, making it moderately durable but still prone to breakage. The sources note that tanzanite, along with topaz and moonstone, has "perfect cleavage and will break easily." Cleavage refers to the tendency of a mineral to break along specific planes of weakness, which is a critical consideration for jewelry design and wear.
Zircon is described as a bright gem with high luster. While its exact hardness is not specified in the provided chunks, it is often recognized for its exceptional brilliance and fire, which can rival that of diamond. Its durability makes it suitable for various jewelry applications, though care should always be taken with any gemstone.
It is important to note that the hardness values for tanzanite and turquoise are derived from the general birthstone chart provided in the sources, which lists hardness for December's stones as 6.5-7. This value likely pertains to tanzanite, as turquoise's hardness is significantly lower. The chart's structure suggests that for December, the listed hardness corresponds to tanzanite, with turquoise and zircon having different properties not fully detailed in the same table.
Symbolism and Metaphysical Beliefs
Each of the December birthstones carries its own set of symbolic meanings and metaphysical beliefs, which have been attributed to them over time.
Turquoise is deeply embedded in the cultural symbolism of the Southwestern United States, where it has been used for millennia. While specific metaphysical properties are not detailed in the provided sources, its long history as a gemstone for beads, pendants, and inlay work suggests it held significant cultural and possibly spiritual value for ancient artisans.
Tanzanite is associated with qualities of protection, healing, and wisdom. Its recent addition to the birthstone list means its metaphysical lore is more modern, but it has quickly become a symbol of the unique and the transformative, given its singular geographic origin and striking color change.
Zircon is often linked to wisdom, honor, and purity. Its brilliant fire and clarity have made it a symbol of light and clarity of thought. In some traditions, it is believed to promote prosperity and success.
The modern birthstone chart often includes "Key Symbolism" for each stone, providing a quick reference for their attributed meanings. For December, these symbols are listed as protection, healing, and wisdom, which collectively encompass the spiritual associations of tanzanite, turquoise, and zircon.
Care and Cleaning
Proper maintenance is essential to preserve the beauty and integrity of these gemstones, given their varying physical properties.
Turquoise, with its low hardness (2.5-4.5), is the most delicate of the three. It is easily scratched and should be protected from sharp blows and abrasive materials. Cleaning should be gentle; avoid harsh chemicals, ultrasonic cleaners, and steam. A soft, damp cloth is sufficient for routine cleaning. Its opacity means it does not require the same level of clarity maintenance as faceted stones, but its surface should be kept free from dirt and oils.
Tanzanite, with a hardness of 6.5-7 and perfect cleavage, requires careful handling to avoid chipping or breaking. It should be stored separately from other jewelry to prevent scratches. Cleaning can be done with warm, soapy water and a soft brush, but ultrasonic cleaners and steam are not recommended due to the risk of thermal shock and exploiting its cleavage planes.
Zircon, while not specified in the sources for care instructions, is generally a durable gemstone. However, like all gemstones, it should be protected from hard impacts. Standard gemstone care applies: clean with warm, soapy water and a soft brush, and avoid harsh chemicals and extreme temperature changes.
For all December birthstones, it is advisable to remove jewelry during activities that could subject the stones to physical stress, such as heavy manual work, sports, or gardening. Professional inspection and cleaning by a jeweler are recommended periodically to ensure settings are secure and stones are in good condition.
Conclusion
The December birthstones—turquoise, tanzanite, and zircon—offer a diverse and captivating selection for those born in the last month of the year. From the ancient, culturally rich turquoise to the modern, vividly colored tanzanite and the brilliantly fiery zircon, each gemstone possesses a unique character, history, and set of properties. Their inclusion on the modern birthstone chart reflects both tradition and the dynamic nature of the gemstone market, where new discoveries and cultural shifts continually reshape our choices. Understanding their geological origins, gemological characteristics, and symbolic meanings allows enthusiasts, buyers, and students to make informed and appreciative selections, ensuring these stones continue to be cherished for generations to come.