December is a month of contrasts—cold winds and warm celebrations, darkness and the glow of holiday lights. In the world of gemstones, December is equally vibrant, offering a selection of birthstones that reflect the month’s rich diversity. The modern December birthstones—tanzanite, turquoise, and zircon—each bring their own unique character, history, and beauty to the table. While these stones are often associated with the month's icy blues and vibrant colors, their stories extend far beyond their appearance, touching on geology, culture, and even mythology.
This article explores the three December birthstones in depth, drawing from historical records, geological data, and cultural lore. We will examine their formation, sources, and gemological properties, as well as the symbolism and care they require. By the end, you will have a comprehensive understanding of what makes these stones not only beautiful but also significant in both the world of gemology and the hearts of those who cherish them.
History and Lore
Tanzanite: A Modern Discovery
Tanzanite is the youngest of the three December birthstones, having been discovered in 1967 in the Merelani Hills of northern Tanzania, near the base of Mount Kilimanjaro. The first tanzanite crystal was found by a Masai tribesman, who stumbled upon the gem while tending to his goats. The stone was identified as a variety of the mineral zoisite, but it wasn’t until 1968 that it was heat-treated to reveal its striking blue-violet colors. It was then named tanzanite in honor of its country of origin.
Tanzanite quickly gained popularity, thanks in large part to the efforts of Tiffany & Co., which launched a major advertising campaign in 1968 to promote the stone. The gem’s vivid colors and high clarity made it an instant sensation, and it soon became a favorite among jewelers and collectors alike. Today, tanzanite is not only a December birthstone but also the gemstone for the 24th wedding anniversary, symbolizing deep love and enduring bonds.
Turquoise: A Stone of Ancient Power
Turquoise, in contrast to tanzanite, is one of the oldest known gemstones, with a history that stretches back thousands of years. The earliest recorded use of turquoise dates to 7,000 BC, when it was found in burial sites in western Iran. Ancient civilizations across the world—from Egypt to China to Native American cultures—prized turquoise for its beauty and the powers they believed it held.
In ancient Egypt, turquoise was considered a sacred stone, often used in the adornments of pharaohs and in burial masks, such as the famous mask of King Tutankhamun. The stone was believed to offer protection and bring good fortune. In China, turquoise was carved into intricate jewelry and decorative objects over 3,000 years ago, symbolizing wisdom and longevity.
Native American tribes, particularly those in the Southwest United States, also held turquoise in high regard. It was used in ceremonies, as a protective talisman, and in jewelry that reflected the wearer’s status and beliefs. The stone was thought to promote healing and spiritual clarity, and it was often placed in burial sites to guide the deceased into the afterlife.
Zircon: The Oldest Mineral on Earth
Zircon is not only a December birthstone but also one of the oldest minerals on Earth, with some zircon crystals dating back 4.4 billion years. Unlike tanzanite and turquoise, which are relatively well-known in the world of gemstones, zircon is less commonly associated with jewelry, though it has a rich history in both geological and cultural contexts.
Historically, zircon was often mistaken for other gems, such as topaz or diamond, due to its brilliance and clarity. It was particularly popular in the Victorian and Art Deco eras, where it was used in rings, pendants, and brooches. Zircon comes in a wide range of colors, from golden yellow and honey brown to blue, green, and colorless, with the blue and colorless varieties being the most sought after in modern times.
Zircon’s use as a birthstone is a relatively recent development, and it is often associated with wisdom, clarity, and spiritual growth. In some cultures, it was believed to have protective properties, helping the wearer avoid harm and maintain inner strength.
Geological Formation and Sources
Tanzanite: A Unique Source
Tanzanite is found exclusively in Tanzania, specifically in the Merelani Hills of northern Tanzania, located near the base of Mount Kilimanjaro. This region is the only place in the world where tanzanite is commercially mined, making it one of the most geologically unique gemstones. The Merelani Hills cover an area that is just 4.3 miles long and 1.2 miles wide, yet it is home to the largest and most valuable tanzanite deposits in the world.
The formation of tanzanite is the result of a rare combination of geological conditions. Tanzanite is a type of zoisite, a silicate mineral that is typically brown or green in its natural state. However, under specific conditions involving heat and pressure, the mineral can transform into the striking blue-violet hues that make tanzanite so valuable. This transformation is what gives tanzanite its pleochroic properties—meaning it displays different colors depending on the angle at which it is viewed.
Mining operations in the Merelani Hills are often large-scale, with thousands of workers involved in the extraction of the gemstone. The mines can be over 100 meters deep, and the surrounding landscape is marked by grass-covered hillsides, rocky soil, and scrub brush. The proximity to Mount Kilimanjaro adds to the uniqueness of the area, as the snow-capped mountain looms in the background.
Turquoise: A Global Treasure
Turquoise is found in a variety of locations around the world, including the United States, Mexico, the Middle East, and China. However, the most valuable and sought-after turquoise comes from the American Southwest and Iran. In the United States, major sources include New Mexico, Arizona, Nevada, and Utah, where turquoise has been mined for centuries. The Cerrillos Hills near Santa Fe, New Mexico, are one of the oldest known turquoise mines in the world, with evidence of mining dating back to 700 AD.
In the Middle East, particularly in Iran, turquoise has been mined and used for thousands of years. The Nishapur region in Iran is known for producing some of the finest turquoise in the world, with a deep blue color and minimal matrix. Kazakhstan is another notable source, home to the Golden Hills variety, which is considered to be among the purest turquoise in the world.
The formation of turquoise is the result of a chemical process involving copper, aluminum, and phosphate. It is created when water containing these elements flows through phosphate-rich sediment. The presence of copper gives turquoise its characteristic blue color, while iron can cause the stone to appear more green, and zinc can give it a yellowish hue.
Zircon: A Diverse and Ancient Gem
Zircon is found in a wide range of geological settings, from granite and metamorphic rocks to alluvial deposits. Some of the most important sources of zircon include Sri Lanka, Australia, Myanmar, Vietnam, and Cambodia, where it is often found in association with sapphire. Zircon’s formation dates back billions of years, with some zircon crystals being among the oldest known minerals on Earth.
The gemstone’s color is influenced by the chemical composition and treatment it undergoes. Naturally occurring zircon can range in color from brown and yellow to red and green, but the most popular varieties today are blue and colorless, which are created through heat treatment. This process involves heating the stone to high temperatures, which alters its crystal structure and produces the desired color.
Zircon is often found in placer deposits, where it has been eroded from its original source and transported by water. These deposits are particularly common in beaches and riverbeds, where the dense and durable nature of zircon allows it to survive the journey. Once extracted, zircon is typically sorted and cut to bring out its natural brilliance and color.
Gemological Properties
Tanzanite: A Stone of Depth and Beauty
Tanzanite is a trigonal mineral with a specific gravity of 3.10 to 3.40 and a refractive index of 1.694 to 1.703. It is pleochroic, meaning it displays different colors depending on the angle at which it is viewed. This property is one of the reasons why tanzanite is so prized—its blue-violet hues can shift dramatically under different lighting conditions.
On the Mohs scale of hardness, tanzanite ranks 6 to 7, which makes it relatively soft for a gemstone. This means that it requires careful handling and is best suited for jewelry that is not worn daily, such as earrings, pendants, and brooches. Tanzanite is also susceptible to high temperatures and sudden temperature changes, which can cause it to crack or lose its color.
The color of tanzanite is the result of a heat treatment that changes its natural brown color into the vibrant blue and violet hues that are so desirable. This treatment is permanent, and there are no additional durability concerns once the stone has been processed.
Turquoise: A Semi-Transparent Gem
Turquoise is a phosphate mineral with a specific gravity of 2.6 to 2.8 and a refractive index of 1.61 to 1.65. It is a trigonal mineral and is semi-transparent to opaque, often displaying matrix patterns—veins of the surrounding rock in which it was formed. These matrix patterns can range from fine lines to bold, swirling designs, and they are considered a natural part of the stone’s character.
On the Mohs scale of hardness, turquoise ranks 5 to 6, making it relatively soft and prone to scratching and chipping. It is also porous, which means it can absorb liquids and oils, potentially altering its color over time. This is why careful cleaning and storage are essential for maintaining the stone’s appearance.
Turquoise is rarely found in its pure form and is often treated to enhance its color and durability. Common treatments include stabilization with resins or waxes, which help to seal the pores and prevent the stone from drying out. Some turquoise is also dyed to achieve a deeper blue color, though this is considered less valuable than untreated turquoise.
Zircon: A Versatile and Durable Gem
Zircon is a zirconium silicate with a specific gravity of 3.9 to 4.7 and a refractive index of 1.92 to 2.01. It is a tetragonal mineral and is known for its high dispersion, which gives it a sparkling appearance similar to that of diamond. Zircon is also pleochroic, meaning it can display different colors when viewed from different angles.
On the Mohs scale of hardness, zircon ranks 6 to 7.5, making it a relatively durable gemstone that is suitable for everyday wear in certain types of jewelry. However, it is susceptible to abrasion, so it should be avoided in rough conditions, such as gardening or sports.
Zircon is often heat-treated to enhance its color. Naturally occurring zircon can be brown, yellow, red, or green, but the blue and colorless varieties are the most popular. The heat treatment is permanent, and it does not affect the stone’s durability or stability. Zircon is also stable when exposed to chemicals, making it a versatile gemstone for a variety of jewelry applications.
Symbolism and Metaphysical Beliefs
Tanzanite: A Stone of Transformation
Tanzanite is often associated with transformation, intuition, and emotional healing. It is believed to help the wearer release old patterns and embrace new possibilities, making it a powerful stone for those undergoing change or seeking personal growth. In modern metaphysical practices, tanzanite is used to activate the throat and third eye chakras, enhancing communication and spiritual awareness.
The stone’s violet and blue hues are thought to have a calming effect, helping to alleviate stress and anxiety. It is also believed to promote empathy and compassion, encouraging deeper connections with others. Some practitioners use tanzanite in meditation to open the heart and mind, allowing for greater insight and clarity.
Turquoise: A Stone of Protection and Clarity
Turquoise has long been considered a stone of protection, believed to ward off negative energies and bring good fortune. In ancient times, it was used as a talisman for travelers and warriors, who believed it would protect them from harm and guide them safely home. The stone was also thought to promote clarity and wisdom, helping the wearer make better decisions and stay focused on their goals.
In Native American cultures, turquoise is considered a spiritual stone that connects the physical and spiritual worlds. It is used in ceremonies and rituals to invoke the guidance of the spirits and to seek protection from the elements. The stone is also believed to promote healing, both physically and emotionally, and is often used in healing ceremonies to restore balance and harmony.
Zircon: A Stone of Wisdom and Clarity
Zircon is often associated with wisdom, clarity, and spiritual growth. It is believed to help the wearer see things more clearly, both literally and metaphorically, and to make sound decisions based on reason and intuition. In ancient times, zircon was used as a protective stone, believed to ward off negative influences and promote inner strength.
The stone is also thought to enhance memory and learning, making it a popular choice for students and scholars. In modern metaphysical practices, zircon is used to activate the crown and throat chakras, promoting spiritual connection and clear communication. Some practitioners believe that zircon can help with emotional healing, allowing the wearer to release past traumas and move forward with confidence.
Care and Cleaning
Tanzanite
Tanzanite is a delicate gemstone that requires careful handling and cleaning to maintain its beauty and durability. It ranks 6 to 7 on the Mohs scale of hardness, making it susceptible to scratches and abrasions. It is also prone to cracking if exposed to high temperatures or sudden temperature changes, and it can be damaged by strong acids such as hydrochloric and hydrofluoric acid.
To clean tanzanite, use warm, soapy water and a soft brush to gently remove any dirt or debris. Avoid using ultrasonic or steam cleaners, as these can damage the stone. It is best to remove tanzanite jewelry before engaging in activities that could expose it to rough handling or harsh chemicals.
When storing tanzanite, keep it in a soft cloth or padded container to prevent it from coming into contact with other jewelry. This will protect it from scratches and other damage. If you plan to wear tanzanite regularly, consider having it set in a protective mounting to reduce the risk of damage.
Turquoise
Turquoise is a porous gemstone that requires special care to maintain its color and luster. It ranks 5 to 6 on the Mohs scale of hardness, making it relatively soft and prone to scratching and chipping. It is also sensitive to oils, lotions, and other chemicals, which can alter its color and appearance.
To clean turquoise, use warm, soapy water and a soft brush to gently remove any dirt or debris. Avoid using ultrasonic or steam cleaners, as these can damage the stone. If the turquoise has been stabilized or dyed, it is important to avoid using harsh chemicals, as these can remove the treatment and alter the stone’s appearance.
When storing turquoise, keep it in a cool, dry place to prevent it from drying out or cracking. It is also a good idea to store turquoise separately from other jewelry, as it can scratch or be scratched by harder gems. If you plan to wear turquoise regularly, consider avoiding activities that could expose it to rough handling or harsh chemicals.
Zircon
Zircon is a relatively durable gemstone that is suitable for everyday wear in certain types of jewelry. It ranks 6 to 7.5 on the Mohs scale of hardness, making it resistant to scratches and abrasions. However, it is susceptible to abrasion, so it should be avoided in rough conditions, such as gardening or sports.
To clean zircon, use warm, soapy water and a soft brush to gently remove any dirt or debris. Avoid using ultrasonic or steam cleaners, as these can damage the stone. It is also important to avoid exposing zircon to high temperatures, as this can alter its color.
When storing zircon, keep it in a soft cloth or padded container to prevent it from coming into contact with other jewelry. This will protect it from scratches and other damage. If you plan to wear zircon regularly, consider avoiding activities that could expose it to rough handling or harsh chemicals.
Conclusion
The December birthstones—tanzanite, turquoise, and zircon—each bring their own unique charm and significance to the world of gemstones. From the deep blue-violet hues of tanzanite to the vibrant blues and greens of turquoise and the sparkling clarity of zircon, these stones reflect the diversity and beauty of the month of December.
Tanzanite, the youngest of the three, was discovered in 1967 in Tanzania and quickly became a fashion icon thanks to Tiffany & Co.. Its pleochroic properties and vibrant colors make it a fascinating gemstone that is both aesthetically pleasing and historically significant.
Turquoise, in contrast, is one of the oldest known gemstones, with a history that spans thousands of years. It has been used by ancient civilizations, from Egypt to Native American cultures, as a symbol of protection, wisdom, and healing. Its matrix patterns and rich colors make it a unique and valuable gemstone that continues to be cherished today.
Zircon, the oldest mineral on Earth, is a versatile and durable gemstone that has been used in jewelry for centuries. Its high dispersion and pleochroic properties give it a sparkling appearance, and its range of colors makes it a popular choice for jewelers and collectors. Whether blue, colorless, or golden, zircon is a fascinating gemstone that continues to capture the imagination.
Together, these three December birthstones offer a rich tapestry of history, beauty, and meaning that makes them perfect choices for those born in December. Whether you are drawn to the deep blues of tanzanite, the vibrant greens of turquoise, or the sparkling clarity of zircon, there is a December birthstone for everyone.