December, the final month of the year, is not only a time of celebration and renewal but also a period rich in symbolism through its birthstones. December is unique in the world of gemstones for its association with four officially recognized birthstones: Turquoise, Tanzanite, Blue Zircon, and Blue Topaz. Each of these gemstones carries a distinct history, a unique set of gemological properties, and a wealth of cultural and symbolic meaning. Together, they reflect the cool, wintry palette of December while offering individuals born in this month a diverse array of options, from the ancient to the newly discovered.
This article explores the significance of December’s birthstones in depth, drawing from their geological origins, historical use, symbolic meanings, and practical considerations for wear and care. Whether you are a gemstone enthusiast, a jewelry buyer, or a student of gemology, this comprehensive guide will provide you with a deeper understanding of the allure and importance of these gems in both historical and modern contexts.
History and Lore of December Birthstones
The tradition of associating gemstones with specific months has ancient roots, with early records dating back to Mesopotamia, where the priestly breastplate in the Book of Exodus is thought to have included 12 gemstones representing the 12 tribes of Israel. This practice was later adopted by the ancient Greeks and Romans, who linked gemstones to the zodiac signs and the days of the month. Over time, the tradition evolved, particularly in the 19th and 20th centuries, when modern birthstone lists began to take shape in Western cultures.
December’s selection of four gemstones reflects the dynamic nature of this tradition. Originally, only Turquoise and Zircon were considered December birthstones. However, the list expanded in the 20th century with the addition of Blue Topaz and Tanzanite. Blue Topaz was added in the 1920s, likely to provide a durable and affordable option for jewelry. Tanzanite, discovered in Tanzania in 1967, was officially recognized as a December birthstone in 2002, making it the most recent addition to the list.
The inclusion of multiple birthstones for December serves several purposes. First, it allows for a broader range of aesthetic choices, from the deep blue-violet of Tanzanite to the clear or golden tones of Zircon. Second, it accommodates different budget ranges, with Blue Topaz being the most durable and relatively affordable, and Tanzanite being the rarest and most expensive. Finally, the variety of options reflects the evolving nature of gemology and the commercial jewelry industry, which seeks to balance tradition with innovation.
Geological Formation and Sources of December Birthstones
Understanding the geological origins of December’s birthstones adds another layer of appreciation to these gems. Each one is formed through unique geological processes and is sourced from distinct regions around the world.
Turquoise
Turquoise is a phosphate mineral composed of copper and aluminum. It forms in the weathering zones of copper deposits, typically in arid environments where water percolates through the rock. This process leads to the formation of its characteristic sky-blue to greenish-blue coloration. Turquoise is known for its porous nature, which often requires stabilization through resin or oil to enhance its durability.
Historically, the oldest and most valuable sources of turquoise are found in Iran, where it has been mined for thousands of years. Other significant sources include the southwestern United States, particularly New Mexico and Arizona, as well as Tibet, India, and Egypt. In the U.S., turquoise is the official state gemstone of New Mexico, a testament to its cultural and historical significance in the region.
Tanzanite
Tanzanite is a trigonal mineral composed of calcium aluminum silicate. It is a relatively new gemstone in the world of jewelry, first discovered in Northern Tanzania in 1967 by a Masai tribesman and later identified as a new variety of columbite by a geologist. The gem is only found in a narrow 10-square-mile area near the base of Mount Kilimanjaro, making it the rarest of all the December birthstones.
Tanzanite’s violet-blue color is due to trace amounts of vanadium and iron, which are activated by heat treatment to enhance the gem’s color. This treatment is essential to bring out its full color potential and is considered stable and permanent.
The rarity of Tanzanite, combined with its alluring color and relatively high hardness (6–7 on the Mohs scale), makes it a prized gemstone in the world of fine jewelry. It is also the official gemstone of Tanzania, symbolizing the country's natural wealth and cultural heritage.
Blue Zircon
Zircon is a zirconium silicate mineral that occurs in a wide range of colors, including colorless, yellow, red, and blue. The blue variety, which is most commonly associated with December, is produced through heat treatment, a process that transforms the natural brown or yellow zircon into a vibrant blue hue.
Zircon has a long history of use, with some of the oldest zircon crystals found in Australia dating back over 4 billion years, making them among the oldest known minerals on Earth. However, zircon has not always been widely used in jewelry. It gained popularity in the 1960s and 1970s, when advancements in gemstone enhancement and marketing made it a more accessible and desirable gemstone.
The primary sources of zircon include Burma (Myanmar), Thailand, Cambodia, Sri Lanka, and Brazil. The blue zircon used in jewelry is typically heat-treated and is known for its brilliance and fire, which rival those of diamonds and other high-refractive-index gems.
Blue Topaz
Topaz is a silicate mineral that occurs in a wide range of colors, including colorless, yellow, red, and blue. The blue variety, which is the most popular for jewelry, is created through irradiation and heat treatment. Natural blue topaz is extremely rare, and the vast majority of blue topaz available on the market today has been enhanced.
Blue topaz is highly durable, with a Mohs hardness of 8, making it one of the most suitable December birthstones for everyday wear. It is also relatively affordable, which has contributed to its popularity in the jewelry industry.
The primary sources of topaz include Brazil, Mexico, Nigeria, and the United States, with Texas being the official state gemstone of the U.S. state of Texas. The Blue Topaz found in Texas is particularly well-known for its light blue color and clarity, making it a favorite among jewelry designers.
Gemological Properties of December Birthstones
To truly appreciate the December birthstones, it is essential to understand their scientific properties, including hardness, refractive index, chemical composition, and coloration.
Turquoise
- Chemical Formula: CuAl₆(PO₄)₄(OH)₈·4H₂O
- Hardness (Mohs Scale): 5–6
- Refractive Index: 1.61–1.65
- Color: Sky blue, greenish-blue
- Transparency: Opaque to translucent
- Luster: Waxy to greasy
- Specific Gravity: 2.6–2.8
Turquoise is relatively soft and porous, which means it requires special care to avoid damage from heat, chemicals, and moisture. It is often stabilized or dyed to improve its durability and color.
Tanzanite
- Chemical Formula: Ca₂Al₃(SiO₄)(Si₂O₇)O(OH)F
- Hardness (Mohs Scale): 6–7
- Refractive Index: 1.694–1.704
- Color: Violet-blue
- Transparency: Transparent to translucent
- Luster: Vitreous
- Specific Gravity: 3.10–3.38
Tanzanite is known for its trichroism, meaning it can display three different colors when viewed from different angles: blue, violet, and brown. This effect is due to the gem's anisotropic nature and is a key feature that distinguishes it from other blue gems.
Blue Zircon
- Chemical Formula: ZrSiO₄
- Hardness (Mohs Scale): 7.5–8
- Refractive Index: 1.92–2.00
- Color: Blue (after heat treatment)
- Transparency: Transparent to translucent
- Luster: Vitreous
- Specific Gravity: 4.6–4.7
Blue zircon is highly refractive and exhibits strong dispersion, which gives it a sparkling, fire-like quality. It is often compared to diamond in terms of brilliance and is sometimes used as a diamond simulant.
Blue Topaz
- Chemical Formula: Al₂SiO₄(F,OH)₂
- Hardness (Mohs Scale): 8
- Refractive Index: 1.61–1.63
- Color: Blue (after irradiation and heat treatment)
- Transparency: Transparent to translucent
- Luster: Vitreous
- Specific Gravity: 3.4–3.6
Blue topaz is one of the hardest and most durable December birthstones, making it ideal for rings, bracelets, and necklaces that are worn daily. It is also relatively affordable, which has contributed to its popularity in engagement rings and everyday jewelry.
| Gemstone | Color | Hardness (Mohs) | Transparency | Luster | Specific Gravity |
|---|---|---|---|---|---|
| Turquoise | Sky blue, greenish-blue | 5–6 | Opaque to translucent | Waxy | 2.6–2.8 |
| Tanzanite | Violet-blue | 6–7 | Transparent to translucent | Vitreous | 3.10–3.38 |
| Blue Zircon | Blue (treated) | 7.5–8 | Transparent | Vitreous | 4.6–4.7 |
| Blue Topaz | Blue (treated) | 8 | Transparent | Vitreous | 3.4–3.6 |
Symbolism and Metaphysical Beliefs
Beyond their physical properties and geological origins, December’s birthstones are also rich in symbolism and metaphysical beliefs. These meanings vary across cultures and eras, but they all contribute to the spiritual and emotional value of these gems.
Turquoise
In many ancient cultures, Turquoise was considered a stone of protection, wisdom, and calmness. It was believed to ward off evil spirits, promote healing, and bring good fortune. In Native American and Egyptian cultures, Turquoise was used in ceremonial jewelry and amulets, symbolizing divine protection and spiritual connection.
Modern metaphysical beliefs attribute Turquoise with the ability to enhance communication, promote emotional balance, and encourage honesty. It is also associated with friendship and protection, making it a popular choice for jewelry that is worn close to the heart.
Tanzanite
Tanzanite is often associated with transformation, intuition, and spiritual growth. Its violet-blue color is said to open the heart and throat chakras, promoting emotional healing, self-expression, and clarity.
In modern metaphysical practices, Tanzanite is believed to help individuals navigate change and uncertainty, making it a particularly fitting stone for December, a time of reflection and renewal. It is also believed to enhance compassion and understanding, making it a popular choice for jewelry that is shared between loved ones.
Blue Zircon
Zircon, particularly in its blue form, is associated with clarity of thought, mental focus, and emotional stability. It is believed to sharpen the mind, enhance memory, and encourage logical thinking.
In ancient times, zircon was thought to be a stone of the night sky, with some cultures believing it to be one of the stars that fell to Earth. This belief gave it a celestial significance, and it was often used in amulets and talismans to protect against misfortune and attract wisdom.
Blue Topaz
Blue Topaz is a stone of calm, peace, and serenity. It is believed to soothe the mind, reduce stress, and promote emotional stability. It is also associated with honesty, truth, and the expression of one's true self.
In some traditions, Blue Topaz is used to attract love and friendship, making it a popular choice for engagement rings and romantic jewelry. It is also believed to enhance creativity and artistic expression, making it a favorite among artists and writers.
Care and Cleaning of December Birthstones
Proper care is essential to preserving the beauty and longevity of December’s birthstones, especially since some of them are relatively soft or porous. Here are some guidelines for each gem:
Turquoise
- Avoid exposure to heat, moisture, and chemicals to prevent discoloration and damage.
- Clean with a soft cloth and mild soap; avoid using ultrasonic or steam cleaners.
- Store separately to avoid scratches from harder gemstones.
- Re-oil or stabilize if the gem becomes dry or loses luster.
Tanzanite
- Avoid exposure to extreme heat or light, as it can cause fading.
- Clean with warm, soapy water and a soft cloth.
- Avoid ultrasonic and steam cleaning, as these can cause internal fractures.
- Store in a soft cloth or padded box to prevent scratches.
Blue Zircon
- Resistant to scratches and wear, but still avoid exposure to harsh chemicals.
- Clean with warm, soapy water and a soft cloth.
- Ultrasonic cleaning is generally safe, but should be used with caution.
- Store in a cool, dry place to avoid thermal shock.
Blue Topaz
- Very durable and easy to care for due to its high hardness.
- Clean with warm, soapy water and a soft cloth.
- Ultrasonic and steam cleaning are generally safe.
- Avoid exposure to extreme heat or light, as it can affect the color.
Conclusion
December’s birthstones—Turquoise, Tanzanite, Blue Zircon, and Blue Topaz—are a testament to the rich history, scientific beauty, and spiritual significance of gemstones. Each of these gems brings its own unique qualities to the table, from the ancient and sacred Turquoise to the modern and rare Tanzanite. Whether you are drawn to the calming blue of Turquoise, the transformative power of Tanzanite, the brilliant clarity of Blue Zircon, or the durable and affordable Blue Topaz, there is a December birthstone to match your personality, style, and needs.
As we continue to explore and appreciate these gems, we are reminded of the endless fascination that gemstones hold—not just for their beauty, but for their deep connection to history, culture, and human emotion. Whether worn as jewelry, talismans, or collector's items, these stones serve as symbols of identity, meaning, and connection—a true reflection of the December spirit.