The final month of the year is uniquely represented by three distinct birthstones: Turquoise, Zircon, and Tanzanite. Each offers a unique interpretation of the color blue, allowing individuals born in December to choose a stone that best suits their personal style. This article explores the history, geological origins, gemological properties, and cultural significance of these three captivating gems, providing a comprehensive guide for enthusiasts and collectors.
History and Lore
The history of December's birthstones spans millennia, with each stone carrying its own legacy. Turquoise is arguably the oldest, with a continuous history of use as a gemstone for thousands of years. In the southwestern United States, Native Americans were using turquoise over 2000 years ago, where ancient artists produced beads, pendants, inlay work, and small sculptures. Turquoise remains an important part of Southwestern culture today. Its journey to modern birthstone lists is more recent; it was traditionally associated with December, a status it still holds.
Zircon has a long history as a gemstone, prized for its bright luster and high refractive index, which gives it a colorful fire similar to diamond. Historically, zircon was used as an alternative stone for diamond. Its inclusion as a modern birthstone for December occurred in 1952, when it replaced lapis lazuli on the official list. This change reflected a shift towards more accessible and brilliant gemstones.
Tanzanite is the newest of the trio, a 20th-century discovery. It is the newest birthstone for the month of December. Most tanzanite sold in jewelry today has a blue to bluish purple to bluish violet color, a trait that was discovered and popularized relatively recently. Its addition to birthstone lists underscores the dynamic nature of these traditions, which can evolve with new discoveries and market trends.
The concept of birthstones itself has evolved. The first modern birthstone list was released in the United States by the National Association of Jewelers in 1912, replacing opaque stones such as bloodstone and sardonyx with clear gems. This list has been updated over time, with additions like spinel for August in 2016 and the three stones for December. The modern list for December typically includes Tanzanite, Blue Zircon, and Blue Topaz, while the traditional list includes Turquoise, Lapis Lazuli, and Zircon. For the purpose of this article, we will focus on the three most commonly cited December stones: Turquoise, Zircon, and Tanzanite.
Geological Formation and Sources
The formation and sourcing of these gems are as diverse as their colors. Turquoise is a blue to blue-green to yellowish green mineral. It is an opaque gemstone, which influences how it is cut and set. While specific mining locations are not detailed in the provided sources, its historical use in the American Southwest points to significant deposits in that region. The sources note that turquoise is mined around the world.
Zircon is a mineral with a high luster and is found in a variety of natural colors, including yellow, red, and brown. However, the vibrant blue color that is most popular in the market today is typically the result of heat treatment applied to naturally occurring brown or yellow zircon. The sources indicate that about 80% of the zircons sold today are blue, with the color produced by treatment. Zircon is mined in various locations globally.
Tanzanite is a relative newcomer to the gemological world. Its color range—from blue to bluish purple to bluish violet—is its defining characteristic. This color is often enhanced through heat treatment, a common practice in the gem trade to improve or alter a stone's appearance. Like the others, tanzanite is mined in various parts of the world, though specific locations are not listed in the provided materials.
Gemological Properties
Understanding the physical and optical properties of these gems is crucial for their care, valuation, and use in jewelry. The following table summarizes key properties for Turquoise, Zircon, and Tanzanite based on the information provided.
| Gemstone | Chemical Composition | Color | Hardness (Mohs) | Clarity/Transparency | Notable Properties |
|---|---|---|---|---|---|
| Turquoise | Hydrated copper & aluminum phosphate | Blue, blue-green, yellowish green | Low (not specified, but noted as easily scratched) | Opaque | Prone to breakage; often cut into cabochons; lab-created versions exist. |
| Zircon | Zirconium silicate (ZrSiO₄) | Naturally yellow, red, brown; treated to blue, green, etc. | High (not specified in sources) | Typically transparent | High luster; high fire (similar to diamond); heat and irradiation treatments common. |
| Tanzanite | Calcium aluminium hydroxyl sorosilicate | Blue, bluish purple, bluish violet | Not specified in sources | Typically transparent | Color changes with viewing angle (pleochroism); heat treatment is standard. |
Turquoise: As an opaque mineral, turquoise is almost always cut into cabochon shapes. The sources note that it is often cut freeform to take full advantage of the rough material. Its low hardness makes it susceptible to scratching, and it is also prone to breakage. This durability concern is shared with other gems like emerald, opal, and peridot. To make it more affordable, lab-created turquoise is available in some stores for cost-conscious shoppers.
Zircon: Zircon is a bright gem with high luster. Its most prized optical property is its high refractive index, which produces a colorful fire similar to that of diamond. This quality led to its historical use as a diamond simulant. Zircon has a reasonably tough hardness, though the exact rating is not provided. It is important to note that zircon is a different mineral from cubic zirconia, a synthetic diamond simulant. The vast majority of blue zircon on the market is produced by heat-treating natural brown or yellow zircon.
Tanzanite: Tanzanite is prized for its unique color, which exhibits pleochroism—showing different colors (blue and violet) when viewed from different angles. This characteristic is a key feature of the stone. Most commercial tanzanite is heat-treated to achieve its desirable blue-to-violet hues. The sources do not specify its hardness, but it is noted to have perfect cleavage, making it a stone that will break easily if struck. This places it in a category with other gems requiring careful handling, such as topaz.
Symbolism and Metaphysical Beliefs
While the sources provided focus primarily on gemological and historical facts, they do touch upon the symbolic meanings and beliefs associated with these stones. The GIA (Source 2) notes that turquoise, tanzanite, and zircon "all have their own unique take on the color blue," allowing a choice that fits one's style. This implies a personal connection based on aesthetic preference.
Beyond aesthetics, some traditional beliefs are referenced. For instance, amethyst (February's birthstone) is said to cure drunkenness and make one quick-witted in business. Similarly, aquamarine and bloodstone (March) are described as evoking calming waters and representing health and strength, respectively. While the specific metaphysical properties of Turquoise, Zircon, and Tanzanite are not detailed in the provided chunks, the broader context of birthstones suggests they carry symbolic weight. Turquoise, with its ancient history in Native American culture, is likely imbued with cultural significance. Zircon's diamond-like fire may symbolize clarity and brilliance. Tanzanite's recent discovery and striking color may represent modernity and uniqueness.
It is important to distinguish between widely accepted gemological facts and cultural or metaphysical beliefs. The sources indicate that some modern beliefs, like those surrounding amethyst, are part of the lore. For December's stones, while specific powers aren't listed, their selection as birthstones inherently ties them to the identity and month of the wearer.
Care and Cleaning
Proper care is essential to maintain the beauty and integrity of any gemstone. The physical properties of Turquoise, Zircon, and Tanzanite dictate specific care requirements.
Turquoise: Due to its low hardness and porous nature, turquoise requires gentle care. It should be protected from harsh chemicals, perfumes, and prolonged exposure to water or sunlight, which can cause discoloration. Cleaning should be done with a soft, dry cloth. Avoid ultrasonic cleaners and steam cleaning, as these can damage the stone or any treatments it may have undergone. Its susceptibility to scratching means it should be stored separately from harder gems.
Zircon: While zircon is relatively hard and durable, it can be brittle due to its crystal structure. It is best to avoid knocking it against hard surfaces. Cleaning can be done with warm soapy water and a soft brush. It is generally safe for ultrasonic cleaning, but caution is advised if the stone has fractures or inclusions. As with all gems, it's wise to remove zircon jewelry during strenuous activities.
Tanzanite: Tanzanite's perfect cleavage makes it particularly vulnerable to breakage. It should never be subjected to sharp blows or pressure. Cleaning should be done with warm, soapy water and a soft brush. Avoid ultrasonic cleaners and steam cleaning, as the vibrations and heat can cause the stone to crack or cleave. It is also recommended to remove tanzanite jewelry before any activity that could risk impact.
For all three gems, storing them separately in a soft cloth or lined jewelry box will prevent scratches and damage. When in doubt, consult a professional jeweler for cleaning and maintenance advice.
Lab-Created and Simulant Options
The market for birthstones includes both natural and man-made alternatives. The sources note that lab-created and simulant birthstones are used to reduce costs and improve the size, color, and clarity of stones. For example, lab-created turquoise is available for cost-conscious shoppers. While not explicitly mentioned for zircon and tanzanite, lab-grown versions of these gems also exist in the market.
It is critically important for consumers to be aware of what they are purchasing. The Federal Trade Commission mandates that salespeople and product labels clearly state if birthstones are man-made and not natural gems. This disclosure is vital because many buyers specifically seek natural stones. Selling synthetics without proper disclosure is a violation of industry guidelines.
Conclusion
Turquoise, Zircon, and Tanzanite each offer a unique pathway to celebrating a December birthday. Turquoise connects the wearer to ancient history and earthy, opaque beauty. Zircon provides brilliant fire and a spectrum of colors, with blue being the most popular. Tanzanite delivers a modern, captivating hue that changes with the light. Together, they represent the full range of blue gemstones, from traditional to contemporary.
Choosing between them depends on personal preference for color, style, and budget, as well as an understanding of their care requirements. Whether drawn to the ancient legacy of turquoise, the diamond-like sparkle of zircon, or the unique dichroism of tanzanite, individuals born in December have a rich selection of gemstones to call their own. As with any gemstone purchase, seeking reputable sources and understanding whether a stone is natural or treated is key to a satisfying acquisition.