December, the final month of the calendar year, is celebrated for its rich traditions, festive celebrations, and the symbolic promise of renewal. It is also notable in the world of gemstones for housing a unique and diverse selection of birthstones. Unlike many months that are associated with a single gemstone, December is one of the few months with multiple birthstones. This article explores the four officially recognized December birthstones—turquoise, tanzanite, zircon, and blue topaz—detailing their historical significance, geological properties, symbolic meanings, and practical care tips. Supported by the latest gemological and historical references, this in-depth review provides a comprehensive look at the allure and value of these December gems.
Historical and Cultural Significance of December Birthstones
The tradition of assigning gemstones to months of the year dates back centuries, with roots in ancient biblical and cultural practices. However, the modern birthstone list has evolved over time, shaped by both tradition and market trends. December is particularly notable for its changing list of birthstones, which has undergone several revisions since the early 20th century.
The earliest known reference to December's birthstone was the ruby. However, by the 1870s, turquoise had been introduced as a December birthstone in the United States, thanks to a pamphlet titled Gregorian Birthstone Poems published by Tiffany & Co. In 1912, the National Association of Jewellers (now Jewellers of America) expanded the list to include lapis lazuli as an alternative to turquoise. By 1952, zircon—particularly blue zircon—was added to the list by the Jewelry Industry Council of America. Finally, in 2002, tanzanite was officially recognized as a December birthstone, reflecting both its growing popularity and its unique geographic origin in Tanzania.
The inclusion of multiple birthstones in December serves a practical purpose: it allows for a variety of options in terms of color, price, and availability. This flexibility ensures that individuals born in December can choose a gemstone that best aligns with their personal preferences and budget. Whether one is drawn to the deep blue of tanzanite, the vibrant blue-green of turquoise, the brilliant sparkle of zircon, or the serene hues of blue topaz, December’s birthstones offer a diverse array of choices.
Geological Formation and Sources
Each of December’s birthstones has a distinct geological origin, formation process, and geographic distribution. Understanding these factors provides insight into the rarity, durability, and aesthetic appeal of each gemstone.
Turquoise
Turquoise is a hydrated phosphate of aluminum and copper with the chemical formula CuAl₆(PO₄)₄(OH)₈·4H₂O. It forms in arid environments, typically in weathered copper ore deposits known as porphyry copper deposits. Rainwater or melted snow percolates through these deposits, dissolving copper sulfides and creating an acidic solution. This copper-rich solution reacts with aluminum and potassium in surrounding rocks, leading to the formation of turquoise in cavities and cracks.
Turquoise is most commonly found in weathered volcanic rock and sedimentary rock, especially in arid regions. Major sources of turquoise include the United States (particularly Arizona and Nevada), Iran, China, and Egypt. The American Southwest has been a significant source of turquoise for thousands of years, with Native American tribes using the stone for jewelry and ceremonial purposes.
Turquoise has a Mohs hardness of 5 to 6, making it relatively soft and prone to scratching or breaking. It is also porous and can easily absorb oils, dyes, and other substances, which can alter its color. Because of its porosity, turquoise is often stabilized with resins or oils to enhance its durability and color.
Tanzanite
Tanzanite is a relatively recent addition to the birthstone list, first discovered in 1967 in Tanzania, from which it takes its name. Chemically, it is a form of columbite-zircon, with the formula Ca₂Al₃(SiO₄)₃(OH). It is a trigonal mineral with a Mohs hardness of 6 to 7, which is moderate for a gemstone.
Tanzanite is unique in that it exhibits trichroism, meaning it displays different colors when viewed from different angles. The most prized tanzanite exhibits a deep blue to violet color, which is enhanced through heat treatment. The gem is only found in a small area near Mount Kilimanjaro in Tanzania, making it one of the rarest gemstones in the world.
Zircon
Zircon is a zirconium silicate with the chemical formula ZrSiO₄. It is a naturally occurring mineral that can be found in a wide range of colors, including brown, yellow, red, and blue. The blue zircon used in jewelry is typically a heat-treated version of brown or red zircon. Zircon has a Mohs hardness of 6 to 7.5, making it relatively durable.
Zircon is found in various parts of the world, including Australia, Sri Lanka, India, and Brazil. It is often included in jewelry for its sparkling brilliance and refractive index, which is among the highest of any gemstone. Zircon is also notable for its high dispersion, giving it a fire and brilliance similar to diamond.
Blue Topaz
Blue topaz is a silicate mineral with the chemical formula Al₂SiO₆. It is a hexagonal crystal that can occur in a variety of colors, but the blue variety is the most popular, particularly in jewelry. The blue color in topaz is usually the result of irradiation treatment, which alters the structure of the crystal and produces the desired hue.
Blue topaz has a Mohs hardness of 8, making it one of the more durable December birthstones. It is found in several countries, including Brazil, the United States, and Nigeria. It is relatively affordable and highly versatile in jewelry design, making it a popular choice for December birthdays.
Gemological Properties
The gemological properties of a gemstone—its color, clarity, hardness, and refractive index—play a significant role in its value and appeal. Here is a detailed breakdown of the key gemological characteristics of each December birthstone:
| Gemstone | Color | Clarity | Hardness (Mohs) | Refractive Index | Chemical Formula |
|---|---|---|---|---|---|
| Turquoise | Blue-green to green | Opaque | 5–6 | 1.61–1.65 | CuAl₆(PO₄)₄(OH)₈·4H₂O |
| Tanzanite | Blue to violet | Usually included | 6–7 | 1.694–1.701 | Ca₂Al₃(SiO₄)₃(OH) |
| Zircon | Colorless, blue, yellow, red | Usually included | 6–7.5 | 1.92–2.01 | ZrSiO₄ |
| Blue Topaz | Blue (often irradiated) | Usually clear | 8 | 1.61–1.63 | Al₂SiO₆ |
Each of these gemstones has distinct visual and physical properties that contribute to their unique appeal. Turquoise is prized for its soft, earthy tones and historic significance, while tanzanite is valued for its rarity and vivid color. Zircon is known for its sparkling brilliance and high dispersion, and blue topaz is favored for its durability and affordability.
Symbolism and Metaphysical Beliefs
Gemstones have long been associated with symbolic meanings and metaphysical properties. These beliefs vary across cultures and time periods, but many December birthstones share common themes related to protection, wisdom, and emotional balance.
Turquoise
Turquoise has been used as a protective talisman for thousands of years. In ancient Egypt, it was associated with the goddess Hathor and was used in amulets and jewelry to bring good fortune and protection. Native American tribes, particularly the Navajo and Hopi, used turquoise in ceremonial objects and jewelry, believing it to promote health, happiness, and spiritual harmony.
In modern times, turquoise is still associated with protection, communication, and emotional balance. It is believed to help calm the mind, enhance self-expression, and promote compassion. These properties make it a popular choice for those seeking emotional healing and spiritual growth.
Tanzanite
Tanzanite is often associated with transformation, intuition, and spiritual awakening. Because of its rarity and unique color, it is seen as a symbol of individuality and inner strength. Some metaphysical practitioners believe that tanzanite helps open the heart and throat chakras, promoting emotional healing, self-expression, and spiritual connection.
Zircon
Zircon is believed to enhance mental clarity, intuition, and grounding. In ancient times, it was used in amulets and talismans to ward off negative energy and promote prosperity. Some cultures believed that zircon could protect against nightmares and bring good luck. In modern metaphysical practices, zircon is often used to enhance focus, memory, and spiritual insight.
Blue Topaz
Blue topaz is associated with calmness, communication, and emotional balance. It is believed to soothe the mind, reduce stress, and promote clear thinking. Some practitioners also use blue topaz to enhance creativity and attract positive energy.
Care and Cleaning
Proper care and cleaning are essential to maintaining the beauty and longevity of December’s birthstones. Because of their varying hardness and porosity, each gemstone requires specific care instructions.
Turquoise
Turquoise is a relatively soft and porous gemstone, so it requires gentle handling. It should be avoided from exposure to water, oils, and acidic substances, as these can damage the stone or alter its color. Cleaning should be done with a soft, dry cloth, and avoiding ultrasonic cleaners and steamers, as these can damage the stability of treated turquoise.
Tanzanite
Tanzanite is moderately durable, with a Mohs hardness of 6 to 7. It can be cleaned with warm, soapy water and a soft cloth, but should be avoided from exposure to harsh chemicals or extreme temperatures, which can cause fractures or color changes.
Zircon
Zircon is fairly durable, with a Mohs hardness of 6 to 7.5. It can be cleaned with warm, soapy water and a soft brush, but should be avoided from exposure to high heat or ultrasonic cleaners, as these can damage the stone or affect its color.
Blue Topaz
Blue topaz is one of the most durable December birthstones, with a Mohs hardness of 8. It can be cleaned with warm, soapy water and a soft brush, and is safe to use with ultrasonic cleaners and steamers. However, it should be avoided from exposure to high heat, as this can alter its color.
Conclusion
December’s birthstones—turquoise, tanzanite, zircon, and blue topaz—offer a diverse and enchanting array of colors, histories, and meanings. From the ancient protective talismans of turquoise to the modern rarity of tanzanite, these gemstones reflect the rich cultural and gemological heritage of the month. Whether one is drawn to the soothing blue of topaz, the sparkling brilliance of zircon, the velvety violet of tanzanite, or the historic allure of turquoise, December’s birthstones provide a meaningful and beautiful way to celebrate the end of the year.
Each gemstone has its unique charm and significance, making them ideal for jewelry design and personal adornment. With proper care and appreciation, these December birthstones can be cherished for generations, serving as a testament to the enduring beauty and symbolism of gemstones.