December, the final month of the year, is celebrated with a rich and varied selection of birthstones. Unlike months that feature a single gemstone, December boasts a collection of stones that reflect its cultural, historical, and geological diversity. These gemstones—blue zircon, blue topaz, tanzanite, lapis lazuli, and turquoise—each bring their own unique allure, symbolism, and properties. From their deep blue hues to their storied pasts, these stones have captivated humans for centuries and continue to play a significant role in jewelry, spirituality, and personal expression.
This article explores the characteristics, origins, historical significance, and cultural meanings of these five December birthstones. We will also examine their gemological properties, how to care for them, and why they remain popular choices for jewelry and personal adornment.
History and Lore
The tradition of birthstones dates back to ancient times, with roots in biblical texts and early cultural practices. The earliest known references to birthstones come from the Breastplate of Aaron described in the Old Testament, which lists twelve gemstones, each corresponding to one of the twelve tribes of Israel. However, the specific stones identified in these ancient texts have been lost to history, and the modern list of birthstones has evolved significantly over time.
The concept of associating gemstones with months of the year gained popularity in the 19th and 20th centuries. Tiffany & Co. played a pivotal role in shaping the modern birthstone list in 1870 with their publication "Gregorian Birthstone Poems," which assigned turquoise as the December birthstone. In 1912, the National Association of Jewellers (now known as the Jewelers of America) expanded the list, designating turquoise as the primary December birthstone and lapis lazuli as an alternative. By 1952, zircon was added to the list, and in 2002, tanzanite was officially recognized as a December birthstone. Blue topaz was also added as a modern alternative to zircon.
These changes reflect the evolving tastes, availability, and cultural significance of gemstones over time. The inclusion of multiple birthstones for December allows for a broader range of options in terms of color, price, and personal meaning. The diversity of December's birthstones also highlights the month's connection to the end of the year, a time of reflection, celebration, and new beginnings.
Geological Formation and Sources
The December birthstones are formed through a variety of geological processes, each influenced by the unique chemical compositions and environmental conditions of their respective origins.
Blue Topaz is a variety of the mineral topaz, which is composed of aluminum silicate with fluoride and hydroxyl. It is typically found in igneous rocks and is formed under high-temperature conditions. Blue topaz is most commonly found in Brazil, although it is also mined in Nigeria, the United States, and other parts of South America. Its deep blue color is often achieved through irradiation and heat treatment, which enhance its natural hues.
Blue Zircon, on the other hand, is a variety of the mineral zircon, which is a zirconium silicate. Zircon is one of the oldest minerals on Earth, with some specimens dating back over four billion years. Blue zircon is typically found in metamorphic and igneous rocks and is often heat-treated to achieve its vibrant blue color. It is mined in several countries, including Cambodia, Vietnam, and Australia.
Tanzanite is a relatively rare gemstone and is the only December birthstone that is found in a single location—near Mount Kilimanjaro in Tanzania. Discovered in 1967, tanzanite is a variety of the mineral zoisite and is known for its striking blue to violet color. Its unique coloration is due to trace amounts of vanadium, which is activated through heat treatment. Tanzanite's rarity and vivid color make it a highly sought-after gemstone.
Lapis Lazuli is a metamorphic rock composed primarily of lazurite, a sodium calcium aluminum silicate. It is known for its deep blue color, which is often flecked with golden pyrite. Lapis lazuli has been mined for thousands of years, with the most famous deposits located in Afghanistan. It has also been found in Russia, Chile, and the United States. The stone's rich color and historical significance have made it a favorite among artists, jewelers, and spiritual practitioners.
Turquoise is an opaque, blue-to-green mineral that is formed through the interaction of water with copper and aluminum minerals. It is typically found in arid regions, particularly in areas with copper deposits. The most famous sources of turquoise include Afghanistan, Iran, and the southwestern United States. Turquoise has been used for centuries in jewelry and ceremonial objects, and its color is often enhanced through dyeing or stabilization processes.
Gemological Properties
Each of the December birthstones has distinct gemological properties that contribute to their beauty and durability.
| Gemstone | Color | Hardness (Mohs) | Chemical Composition | Refractive Index | Cleavage | Transparency |
|---|---|---|---|---|---|---|
| Blue Topaz | Blue | 8 | Al₂SiO₄(F,OH)₂ | 1.62–1.64 | None | Transparent |
| Blue Zircon | Blue | 6–7.5 | ZrSiO₄ | 1.92–2.01 | Perfect | Transparent |
| Tanzanite | Blue to violet | 6–7 | Ca₂Al₃(PO₄)₃(OH)₃·H₂O | 1.694–1.701 | Perfect | Translucent |
| Lapis Lazuli | Deep blue with gold | 5–6 | Lazurite, calcite, pyrite | 1.5–1.7 | None | Opaque |
| Turquoise | Blue-green | 5–6 | CuAl₆(PO₄)₄(OH)₈·4H₂O | 1.61–1.65 | None | Opaque |
Blue Topaz is one of the hardest December birthstones, with a hardness of 8 on the Mohs scale. It is durable and resistant to scratches, making it an excellent choice for everyday jewelry. Its refractive index ranges from 1.62 to 1.64, and it has no cleavage, meaning it is less likely to break under pressure.
Blue Zircon has a hardness of 6 to 7.5 on the Mohs scale, making it slightly more delicate than blue topaz. It is known for its high refractive index, which gives it a brilliant, fire-like appearance. However, blue zircon has perfect cleavage, which means it can be prone to chipping or breaking if struck at the right angle. Careful handling and proper setting are essential to preserve its beauty.
Tanzanite has a hardness of 6 to 7 on the Mohs scale, placing it in the moderate range for durability. It has perfect cleavage, which makes it susceptible to damage if not set properly. Tanzanite's refractive index ranges from 1.694 to 1.701, and its unique coloration makes it a standout gemstone. Due to its rarity and beauty, tanzanite is often used in statement pieces rather than everyday wear.
Lapis Lazuli is a relatively soft gemstone, with a hardness of 5 to 6 on the Mohs scale. It is composed of several minerals, including lazurite, calcite, and pyrite. Its deep blue color and golden flecks make it a visually striking gemstone, but its softness means it requires careful handling. It is opaque and does not have cleavage, making it less prone to breaking, but it can still be scratched or dulled with improper care.
Turquoise has a hardness of 5 to 6 on the Mohs scale and is also a soft gemstone. It is opaque and is often stabilized or dyed to enhance its color and durability. While it is a popular choice for jewelry, especially in the southwestern United States, it requires special care to prevent damage from heat, moisture, and chemicals.
Symbolism and Metaphysical Beliefs
The December birthstones have been associated with various symbolic and metaphysical properties across different cultures and eras. These beliefs have contributed to their enduring popularity and have influenced their use in jewelry, art, and spiritual practices.
Blue Topaz is often associated with calmness, clarity, and emotional healing. It is believed to enhance mental focus and promote inner peace. Some cultures also associate blue topaz with protection and good fortune, making it a popular choice for talismans and protective jewelry.
Blue Zircon is known for its brilliance and is often referred to as the "gem of fire." It is believed to bring wisdom, prosperity, and spiritual insight. In some traditions, blue zircon is associated with the heart and is thought to enhance emotional stability and self-love.
Tanzanite is a relatively modern gemstone, but it has quickly become associated with transformation, intuition, and spiritual growth. Its unique blue to violet color is believed to open the third eye chakra, enhancing one's ability to see beyond the physical world and access higher states of consciousness.
Lapis Lazuli has a long history of use in spiritual and intellectual pursuits. It is associated with wisdom, truth, and enlightenment. In ancient times, it was believed to be a stone of the gods and was used in the adornment of royalty and high priests. Today, it is still valued for its ability to enhance mental clarity and stimulate creativity.
Turquoise has been revered for centuries as a protective stone. It is believed to bring good fortune, ward off evil, and promote healing. In Native American traditions, turquoise is considered a sacred stone that connects the earth and the sky. It is often used in ceremonial jewelry and is believed to bring balance and harmony to the wearer.
Care and Cleaning
Proper care and cleaning are essential to maintaining the beauty and longevity of December birthstone jewelry. Each gemstone has specific requirements based on its hardness, cleavage, and sensitivity to environmental factors.
Blue Topaz is relatively durable and can be cleaned with mild soap and warm water. It can also be cleaned with ultrasonic and steam cleaners. However, it should be kept away from harsh chemicals and extreme temperatures to avoid damage.
Blue Zircon requires more careful handling due to its perfect cleavage. It should be cleaned with mild soap and warm water and should not be exposed to ultrasonic or steam cleaning, as these methods can cause damage. It is also advisable to avoid exposing blue zircon to sudden temperature changes or physical shocks.
Tanzanite should be cleaned with mild soap and warm water and should not be subjected to ultrasonic or steam cleaning. It is also important to protect tanzanite from exposure to high heat and direct sunlight, as these can cause fading or damage. Due to its perfect cleavage, tanzanite should be handled with care to avoid chipping or breaking.
Lapis Lazuli is a soft gemstone and should be cleaned with a soft cloth and mild soap. It should not be exposed to harsh chemicals or abrasive materials, as these can scratch or dull its surface. Lapis lazuli should also be stored separately from other gemstones to prevent scratching.
Turquoise is a porous gemstone and should be cleaned with a soft cloth and mild soap. It should not be exposed to harsh chemicals, heat, or moisture, as these can cause damage or discoloration. Turquoise should also be stored in a cool, dry place to prevent fading or deterioration.
Conclusion
December's birthstones—blue zircon, blue topaz, tanzanite, lapis lazuli, and turquoise—offer a rich and diverse selection of gemstones that reflect the month's cultural, historical, and geological significance. Each stone has its own unique properties, symbolism, and care requirements, making them valuable choices for jewelry and personal adornment. From their deep blue hues to their storied pasts, these gemstones continue to captivate gemstone enthusiasts, jewelry buyers, and students of gemology alike.
Whether chosen for their beauty, history, or metaphysical properties, December's birthstones provide a meaningful and expressive way to connect with the past and celebrate individuality. With proper care and appreciation, these gems can be cherished for generations, serving as both personal treasures and enduring symbols of the month of December.