The month of December is uniquely represented by three distinct birthstones: turquoise, zircon, and tanzanite. Each offers a unique interpretation of the color blue, a hue often associated with winter skies and icy landscapes. This article provides a comprehensive examination of these three gemstones, drawing upon their geological origins, gemological properties, historical significance, and their roles in both traditional and modern birthstone lists. While all three are linked to December, their individual characteristics—ranging from the ancient, opaque charm of turquoise to the brilliant fire of zircon and the pleochroic color shift of tanzanite—provide a diverse palette for those born in the final month of the year.
The modern birthstone list, largely standardized in the early 20th century, has evolved to include these stones. Turquoise holds a position in traditional lists, while zircon and tanzanite are more modern additions. Understanding each stone's unique story is essential for appreciating their collective significance.
Historical Significance and Lore
The history of these December birthstones spans millennia, with turquoise having the deepest roots in human culture. Evidence of its use dates back over 2000 years in the Southwestern United States, where Native American artists crafted beads, pendants, inlay work, and small sculptures. Turquoise remains an integral part of Southwestern culture today, its vibrant blue-green hue a symbol of the region's artistic heritage. Its long-standing use as a gemstone is attributed to its distinctive color and its suitability for opaque cabochon cuts, which showcase its natural beauty without the need for transparency.
In contrast, zircon’s historical narrative is intertwined with its visual properties. Its high luster and colorful fire, which can be similar to that of a diamond, led to its historical use as a diamond alternative. This characteristic made it a valuable gem in eras when diamond sources were limited. Zircon's journey to becoming a modern birthstone is more recent; it replaced lapis lazuli on the official list in 1952. This change reflected a shift in availability and consumer preference, as large deposits of zircon were discovered and processed.
Tanzanite is the newest addition to the December birthstone family. Its commercial history began only in the 20th century, following its discovery in Tanzania. Most tanzanite available in the market today has undergone heat treatment to achieve its characteristic blue to bluish purple color. This treatment process is a standard part of its preparation for the gem and jewelry trade. The gem’s appeal lies not only in its color but also in its unique visual property: its color changes depending on the viewing angle, a phenomenon known as pleochroism. This dynamic quality has contributed to its rapid rise in popularity as a modern birthstone.
Geological Formation and Sources
Understanding the geological origins of these stones provides insight into their formation and the locations where they are mined.
Turquoise is a mineral that forms in arid regions where acidic, copper-rich groundwater interacts with minerals containing aluminum and phosphorus. This process occurs over millions of years, creating nodules or veins in host rock. While the Southwestern United States is historically significant for turquoise use, the primary sources for commercial turquoise today are not explicitly detailed in the provided materials. However, the material notes that turquoise jewelry is generally not extremely expensive, making it an accessible gemstone for a wide audience.
Zircon is a mineral occurring in a variety of forms and colors. Natural zircons are commonly found in yellow, red, or brown hues. The material does not specify primary mining locations for zircon, but it does indicate that treatments are commonly applied. Heat and irradiation are used to transform the natural colors into more marketable shades like blue, green, and others. Approximately 80% of the zircons sold today are blue, a color achieved through this treatment process. The ability to alter its color has made zircon a versatile gem in the marketplace.
Tanzanite is a variety of the mineral zoisite. Its formation is linked to specific geological conditions. The provided sources do not detail the exact formation process or primary mining locations for tanzanite. However, its name indicates its geographic origin in Tanzania. As a relatively new gemstone, its geological story is still being fully documented, but its limited geographic source contributes to its rarity and value.
Gemological Properties
A detailed comparison of the gemological properties of turquoise, zircon, and tanzanite reveals their distinct physical characteristics, which influence their use in jewelry and their care requirements.
| Property | Turquoise | Zircon | Tanzanite |
|---|---|---|---|
| Color | Blue to blue-green to yellowish green. Bright blue is most preferred. | Naturally yellow, red, or brown. Treated to produce blue, green, and other colors. Blue is most popular (80% of market). | Blue to bluish purple to bluish violet (typically after heat treatment). Color shifts with viewing angle. |
| Clarity/Transparency | Opaque. | Transparent to translucent. High luster. | Typically transparent. |
| Hardness (Mohs) | Low hardness; easily scratched. | Not explicitly stated, but high luster suggests good hardness. | Not explicitly stated. |
| Cut | Usually cut into cabochons, often freeform to maximize rough material. | Cut to showcase its fire and luster. | Cut to enhance its color and pleochroic properties. |
| Treatment | Natural color is preferred. | Heat and irradiation are standard treatments to alter color. | Heat treatment is standard to produce the blue color. |
| Durability Concerns | Low hardness and porous nature make it susceptible to scratching and damage. | Prone to breakage. | Prone to breakage due to perfect cleavage. |
Turquoise is an opaque mineral, prized for its color rather than transparency. Its low hardness (stated as "easily scratched") makes it susceptible to damage, which is why it is most often set in protective settings like sterling silver and cut into cabochons. The material notes that bright blue is the most preferred color, and its opaque nature means it is not faceted like transparent gems.
Zircon is described as a "bright gem with high luster," and many specimens produce a "colorful fire that is similar to diamond." This optical property, known as high refractive index and strong dispersion, makes it a brilliant gem. While its exact hardness is not specified, its use as a diamond alternative suggests it has sufficient durability for jewelry, though the material notes it is "prone to breakage." Its transparency allows for faceted cuts that maximize its brilliance.
Tanzanite is known for its dramatic color change, a property called pleochroism. The material states that its color "changes depending upon the angle of viewing." Most tanzanite sold is heat-treated to achieve its desirable blue hues. Like zircon, tanzanite is noted to have "perfect cleavage and will break easily," indicating a need for careful handling and setting.
Symbolism and Metaphysical Beliefs
The provided materials offer limited information on the symbolic or metaphysical beliefs associated with these specific December birthstones. The sources focus primarily on historical use, gemological properties, and market information rather than traditional lore or modern metaphysical claims. For instance, while turquoise is noted for its long history in Southwestern culture, no specific symbolic meaning (such as protection or healing) is attributed to it in the chunks. Similarly, zircon and tanzanite are discussed in terms of their visual appeal and treatment processes, without reference to any associated beliefs or meanings. Therefore, any discussion of symbolism or metaphysical properties would be based on information not present in the provided sources and cannot be included in this article.
Care and Cleaning
The care and cleaning of these gemstones are directly related to their physical properties, particularly hardness and cleavage.
Turquoise, with its low hardness, is "easily scratched." It should be cleaned with mild soap, water, and a soft cloth. Avoid ultrasonic cleaners, steam cleaners, and harsh chemicals, which can damage the stone or its matrix. Due to its porous nature, turquoise can absorb oils and chemicals, so it should be kept away from lotions, perfumes, and other cosmetics.
Zircon and Tanzanite are both noted to be "prone to breakage." Zircon does not have perfect cleavage in all directions, but it can be brittle. Tanzanite, with its perfect cleavage, is particularly vulnerable to impact. Both stones should be handled with care to avoid knocks and drops. Cleaning should be done with warm, soapy water and a soft brush. Avoid ultrasonic cleaners and extreme temperature changes, which can cause fractures in these gems. Given their potential for breakage, protective settings are recommended for jewelry intended for daily wear.
Modern and Traditional Birthstone Lists
The assignment of birthstones to months has evolved over time, with some stones being added to modern lists while traditional stones remain in use. The provided sources illustrate this evolution for December.
The traditional December birthstone list includes turquoise and lapis lazuli. Turquoise has a long history and is still widely recognized as a December stone.
The modern list, however, has expanded to include zircon and tanzanite. Zircon was added to most lists in 1952, replacing lapis lazuli. Its inclusion is due to its beauty and the availability of treated stones in appealing colors. Tanzanite is the newest addition, recognized for its unique color and pleochroic properties.
Some modern lists also include blue topaz as a December birthstone. Blue topaz, while not detailed in the provided chunks about December stones, is mentioned in the context of November birthstones (topaz and citrine) and in a modern birthstone chart. The availability of large deposits in Brazil has made blue topaz an affordable and popular choice.
This variety allows individuals born in December to choose a stone that best fits their personal style, budget, and appreciation for history or modernity. The coexistence of traditional and modern options reflects the dynamic nature of birthstone traditions.
Conclusion
Turquoise, zircon, and tanzanite each offer a distinct pathway into the world of December birthstones. Turquoise connects the wearer to ancient traditions and a rich cultural history, particularly in the Southwestern United States. Its opaque, blue-green cabochons are a testament to enduring natural beauty. Zircon, with its diamond-like fire and versatility of color, bridges historical gem use with modern treatment techniques, offering brilliance and sparkle. Tanzanite, the newest of the trio, captivates with its dramatic color shift and limited geographic origin, representing a modern discovery with immediate appeal.
Together, these three stones provide a comprehensive range of options for December birthdays. Their differences in origin, appearance, and care requirements highlight the diversity of the mineral kingdom. Whether chosen for its historical significance, its brilliant fire, or its dynamic color, each of these birthstones carries the unique legacy of being born from the earth and cherished by humanity. The modern birthstone list, by incorporating zircon and tanzanite alongside traditional turquoise, acknowledges this diversity and ensures that those born in December have a rich selection of gems to call their own.