December is a month of transition and celebration, marking the end of one year and the anticipation of the next. For those born during this time, the tradition of birthstones offers a unique connection to the world of gemology. December is one of only two months with multiple birthstones, and its selection includes some of the most captivating and historically significant gemstones in the world. These include turquoise, zircon (particularly blue zircon), and tanzanite. In some traditions, lapis lazuli, blue topaz, and even ruby have also been considered as December birthstones. This article delves into the rich history, gemological properties, cultural symbolism, and practical care of these December birthstones, drawing from a range of reliable sources in the field of gemology and mineralogy.
A Rich Historical Background
The concept of birthstones dates back to ancient times, with the earliest references found in the Bible’s Book of Exodus, where the High Priest’s breastplate was adorned with twelve gemstones, each representing a tribe of Israel. Over the centuries, these associations evolved, and by the 18th and 19th centuries, the idea of assigning gemstones to each month of the year became more standardized.
December’s birthstones have undergone several changes in this timeline. Initially, ruby was associated with December in some ancient traditions. By the 19th century, turquoise was recognized as the primary birthstone for December, as documented in a 1870 pamphlet by Tiffany & Co. In 1912, the National Association of Jewellers (now the American Gem Trade Association) listed turquoise as the primary December birthstone and lapis lazuli as an alternative. In 1952, the Jewelry Industry Council of America added zircon to the list, and in 2002, tanzanite was officially recognized as a December birthstone.
The inclusion of multiple December birthstones reflects both practical and cultural considerations. While turquoise and lapis lazuli are traditional and have deep historical significance, blue zircon, blue topaz, and tanzanite were added to provide more affordable and modern alternatives. This evolution highlights the dynamic nature of birthstone traditions and their adaptation to changing trends and availability of gem materials.
Geological Formation and Sources
Turquoise
Turquoise is a phosphate mineral composed of copper aluminum phosphate and is formed through the interaction of water with copper ore deposits. It typically forms in weathered volcanic rock or sedimentary rock in arid environments. This process involves acidic water carrying copper from deeper deposits and reacting with aluminum and potassium in the rocks, leading to the formation of turquoise in cavities.
The most notable sources of turquoise are found in North America, particularly in Arizona, Nevada, and New Mexico in the United States. It is also found in China, Egypt, Iran, and Russia. Turquoise is a relatively soft gemstone, with a Mohs hardness of 5–6, making it more prone to scratches and damage compared to harder gemstones like diamonds or sapphires. It is also porous, which means it can absorb oils and pigments, potentially changing its color over time.
Zircon
Zircon is a zirconium silicate mineral and is known for its high refractive index, which gives it a brilliant sparkle. It occurs in a wide range of colors, including blue, yellow, green, brown, and colorless. The blue zircon most commonly associated with December is produced through heat treatment of natural zircon.
Zircon is found in various locations around the world, including Australia, India, Brazil, and the United States. It is a relatively hard gemstone, with a Mohs hardness of 6–7.5, making it durable and suitable for everyday wear in jewelry.
Tanzanite
Tanzanite is a rare gemstone that is only found in Tanzania, near the Serengeti plains, and was first discovered in the 1960s. It is a trigonal mineral composed of calcium aluminum silicate and is known for its violet-blue color, which is caused by trace amounts of vanadium. Tanzanite is a relatively soft gemstone, with a Mohs hardness of 6–7, and it is pleochroic, meaning it can display different colors when viewed from different angles.
The rarity of tanzanite has contributed to its popularity as a birthstone and as a luxury gemstone. Its unique color and limited geographic source make it highly sought after by collectors and jewelry designers.
Gemological Properties
The following table summarizes the key gemological properties of the December birthstones, based on the sources provided:
| Gemstone | Color | Mohs Hardness | Chemical Composition | Source Locations |
|---|---|---|---|---|
| Turquoise | Blue-green | 5–6 | Copper aluminum phosphate | USA, China, Egypt, Iran, Russia |
| Blue Zircon | Blue | 6–7.5 | Zirconium silicate | Australia, India, Brazil, USA |
| Tanzanite | Violet-blue | 6–7 | Calcium aluminum silicate | Tanzania |
These properties influence not only the appearance of the gemstones but also their suitability for different types of jewelry and their care requirements.
Symbolism and Cultural Significance
The December birthstones have long been associated with a range of symbolic meanings and metaphysical properties, many of which have been passed down through centuries of cultural and spiritual traditions.
Turquoise
Turquoise has been revered across various cultures for its protective, calming, and spiritually uplifting properties. In ancient Egypt, it was used in amulets and was believed to provide protection and wisdom. In Native American cultures, it is considered a sacred stone, often used in rituals and ceremonies to connect with the earth and promote healing.
Turquoise is associated with truth, communication, and emotional balance. It is believed to enhance self-expression and inner clarity, making it a popular choice for those who seek to improve their communication skills and emotional well-being. It is also thought to bring good fortune and protection, particularly in times of uncertainty or change.
Zircon
Zircon, particularly blue zircon, is known for its brilliant sparkle and high refractive index, which gives it a diamond-like appearance. In some cultures, it is believed to enhance mental clarity and intuition, helping individuals to make better decisions and navigate complex situations.
Zircon is also associated with wisdom and spiritual awakening, and it is said to support dream work and psychic development. In ancient times, it was considered a stone of the night, used to guide travelers through the dark and to bring clarity in times of confusion.
Tanzanite
Tanzanite is a relatively modern gemstone, but it has quickly gained popularity for its emotional and spiritual properties. It is often associated with transformation, balance, and emotional healing. Its violet-blue color is believed to stimulate the third eye and crown chakras, promoting inner peace and spiritual insight.
Tanzanite is also thought to support emotional resilience, helping individuals to process difficult emotions and move through periods of change with greater ease. Its limited geographic source and short supply also make it a symbol of rarity and exclusivity, adding to its allure.
Care and Maintenance
Proper care is essential for preserving the beauty and integrity of December birthstone jewelry. The following guidelines are based on the gemological properties of each stone:
Turquoise
- Softness and porosity: Turquoise is a soft and porous gemstone, which makes it susceptible to scratches, discoloration, and damage from oils and chemicals.
- Avoid harsh chemicals: Never clean turquoise with ammonia, bleach, or acidic solutions, as these can damage its surface or cause color loss.
- Moisture sensitivity: Turquoise can become dry and brittle if it loses its moisture content. To prevent this, store it in a cool, dry place and avoid exposing it to extreme temperature changes.
- Cleaning: Gently clean turquoise with a soft cloth and mild soap. Avoid using ultrasonic cleaners, as they can damage the stone.
Zircon
- Hardness and durability: Zircon is harder than turquoise, with a Mohs hardness of 6–7.5, making it more durable for everyday wear.
- Heat sensitivity: Some zircons, particularly those that have been heat-treated, can be sensitive to high temperatures. Avoid exposing zircon to extreme heat, as this can cause color changes or damage.
- Cleaning: Zircon can be cleaned with a soft brush and mild soap. Ultrasonic cleaners can be used with caution, but it is best to consult a professional jeweler before using them.
Tanzanite
- Softness and pleochroism: Tanzanite has a Mohs hardness of 6–7, making it softer than zircon and more prone to scratches and abrasions. It is also pleochroic, meaning it can display different colors when viewed from different angles.
- Light sensitivity: Tanzanite can fade if exposed to prolonged sunlight, so it is best to store it in a dark, cool place when not in use.
- Cleaning: Clean tanzanite with a soft cloth and mild soap. Avoid using ultrasonic cleaners, as they can damage the stone’s surface.
Conclusion
December is a month of celebration, reflection, and anticipation, and the gemstones associated with this month reflect its rich cultural and historical significance. From the soft, pastel hues of turquoise to the brilliant sparkle of blue zircon and the rare, violet-blue glow of tanzanite, each December birthstone carries a unique story and a set of symbolic meanings. Whether worn for aesthetic appeal, personal significance, or spiritual connection, these gemstones serve as a beautiful and meaningful way to honor those born in December.
Understanding the history, properties, and care of these gemstones allows for a deeper appreciation of their value and beauty. Whether you are a gemstone enthusiast, a jewelry buyer, or simply curious about the world of birthstones, the December birthstones offer a fascinating glimpse into the intersection of science, culture, and tradition.