December is the only month in the calendar year to boast four recognized birthstones, each with its own unique charm, history, and symbolism. These include Turquoise, Tanzanite, Blue Zircon, and Blue Topaz. The tradition of associating gemstones with birth months has ancient roots and has evolved over time, influenced by cultural beliefs, scientific discoveries, and market trends. For those born on or around December 21, the zodiac sign is Sagittarius, and in some traditions, specific stones like Tanzanite are considered particularly relevant.
This article explores the scientific properties, historical significance, cultural symbolism, and modern uses of the four December birthstones, with a focus on their relevance to Sagittarius and December-born individuals.
Introduction
December, the final month of the year, is rich in symbolism and celebration—from the Winter Solstice to Christmas, Hanukkah, Kwanzaa, and New Year’s Eve. It is also a month of transformation, and the gemstones associated with it reflect this theme of change and renewal. The birthstones of December are particularly interesting because they include both historical and modern discoveries. For example, Tanzanite was first marketed in the 1960s and was not added to the official birthstone list until 2002, whereas Turquoise has been revered for millennia by ancient civilizations such as the Egyptians, Chinese, and Native Americans.
The diversity of December birthstones—ranging from the deep blue of Turquoise to the vibrant violet-blue of Tanzanite, and the sparkling clarity of Blue Topaz—provides a broad spectrum of options for jewelry and personal adornment. Each gemstone has distinct physical and metaphysical properties, and they are all believed to offer unique healing, protective, or spiritual benefits.
This article delves into the geological and chemical properties, historical usage, cultural symbolism, and practical care of these four gemstones, making it a comprehensive resource for gemstone enthusiasts, jewelry buyers, and students of gemology.
History and Lore
The tradition of assigning gemstones to birth months is ancient, with roots in Biblical and Roman sources. The earliest known list of birthstones is found in the Book of Exodus, which describes the 12 stones on Aaron’s breastplate, representing the 12 tribes of Israel. These stones were later interpreted as corresponding to the 12 months of the year.
The modern December birthstone list, however, has evolved significantly. The earliest recorded December birthstone was Ruby, based on the Gregorian Birthstone Poems from 1870. By 1912, Turquoise became the primary December birthstone, and Lapis Lazuli was added as an alternative by the National Association of Jewelers (now the Jewelers of America). In 1952, Zircon, particularly Blue Zircon, was added to the list by the Jewelry Industry Council of America, and in 2002, Tanzanite was officially recognized as a December birthstone.
This expansion reflects the cultural and commercial evolution of birthstone traditions. Tanzanite, for instance, was discovered in Tanzania in the 1960s and was heavily promoted by Tiffany & Co., making it a modern gemstone with global appeal. Similarly, Blue Topaz has become a popular choice due to its durability and affordability, making it suitable for daily wear jewelry.
The zodiacal association of December with Sagittarius (November 22–December 21) and Capricorn (December 22–January 19) also influences the choice of birthstones. For example, Tanzanite is considered a Sagittarius birthstone in some traditions, and is believed to enhance exploration, wisdom, and spiritual insight, aligning with the traits of Sagittarius individuals.
In ancient Indian astrology, Turquoise is the birthstone for Sagittarius, and it is believed to promote good health and healing. It was also considered a protective stone worn in direct contact with the skin, a practice still observed in some Hindu traditions.
Geological Formation and Sources
Each of the four December birthstones is formed under distinct geological conditions, and their mineral composition and geographic distribution give them unique characteristics.
Turquoise
Turquoise is a phosphide mineral composed of copper and aluminum phosphate, with the chemical formula CuAl₆(PO₄)₄(OH)₈·4H₂O. It forms in phosphatic limestones exposed to copper-rich water, typically in desert environments. The most famous sources include:
- Iran (historically known for "Persian turquoise")
- Nevada, USA
- Mexico
- China
- Egypt
Turquoise is known for its characteristic blue-green color, which can vary depending on the presence of iron (green) or copper (blue). It is also porous and soft, with a Mohs hardness of 5–6, making it more susceptible to scratches and damage.
Tanzanite
Tanzanite is a trigonal mineral and a variety of zoisite, with the chemical formula Ca₂Al₃(SiO₄)(OH)₃·(OH). It was discovered in 1967 in Tanzania, near Mount Kilimanjaro, and is exclusively found in that region. The mineral's vibrant blue to violet-blue color is due to trivalent iron (Fe³⁺) in the crystal structure.
Tanzanite is known for its strong pleochroism, meaning it displays different colors (blue, purple, and brown) when viewed from different angles. It is typically heat-treated to enhance its color and clarity, making it more vivid and uniform.
With a Mohs hardness of 6–7, tanzanite is relatively durable, but it has a cleavage, which can make it prone to chipping under impact.
Blue Zircon
Blue Zircon is a zirconium silicate with the chemical formula ZrSiO₄. Natural brown zircon is often heat-treated to produce blue, colorless, or yellow varieties. Blue Zircon is one of the oldest known gemstones, with some samples dating back 2 billion years.
It is found in various parts of the world, including:
- Australia
- Sri Lanka
- Madagascar
- Brazil
Blue Zircon has a high refractive index (1.92–2.01), giving it a sparkling brilliance similar to diamond. It has a Mohs hardness of 6.5–7.5, making it durable for everyday wear, though it can be brittle due to its cleavage.
Blue Topaz
Blue Topaz is a silicate mineral with the chemical formula Al₂SiO₆. Natural blue topaz is rare, and most commercially available stones are irradiated and heat-treated to enhance their blue color.
The most important sources of topaz include:
- Brazil
- Nepal
- Myanmar
- Russia
Blue Topaz has a Mohs hardness of 8, making it very durable, and it has no cleavage, which means it is less likely to chip or crack. It is also relatively affordable, making it a popular choice for everyday jewelry.
Gemological Properties
| Gemstone | Color | Hardness (Mohs) | Chemical Formula | Refractive Index (RI) | Cleavage | Sources |
|---|---|---|---|---|---|---|
| Turquoise | Blue, green, or blue-green | 5–6 | CuAl₆(PO₄)₄(OH)₈·4H₂O | 1.61–1.65 | Yes | Iran, Nevada, Mexico, China, Egypt |
| Tanzanite | Blue, purple, or violet-blue | 6–7 | Ca₂Al₃(SiO₄)(OH)₃·(OH) | 1.69–1.70 | Yes | Tanzania |
| Blue Zircon | Blue, colorless, or yellow | 6.5–7.5 | ZrSiO₄ | 1.92–2.01 | Yes | Australia, Sri Lanka, Madagascar, Brazil |
| Blue Topaz | Blue | 8 | Al₂SiO₆ | 1.61–1.63 | No | Brazil, Nepal, Myanmar, Russia |
These properties affect how the gemstones are cut, set, and worn. For instance, Tanzanite and Blue Zircon require gentle handling due to their cleavage, while Blue Topaz is more versatile for daily wear due to its higher hardness and no cleavage.
Symbolism and Metaphysical Beliefs
The gemstones of December are not only appreciated for their aesthetic and physical properties, but also for their symbolic and spiritual meanings.
Turquoise
- Symbolism: Protection, wisdom, healing, and good fortune.
- Metaphysical Properties: Turquoise is often referred to as the "stone of protection", and it is believed to soothe the mind, enhance communication, and promote emotional stability.
- Cultural Beliefs: In Native American cultures, turquoise is considered a sacred stone that connects the earth and sky. It was used in ceremonial jewelry, amulets, and healing rituals.
Tanzanite
- Symbolism: Transformation, intuition, and spiritual growth.
- Metaphysical Properties: Tanzanite is considered a stone of transformation, helping the wearer to embrace change, heal emotional wounds, and expand their consciousness.
- Cultural Beliefs: As a modern gemstone, Tanzanite has strong associations with spiritual awakening, and it is often used in chakra work, particularly for the third eye and throat chakras.
Blue Zircon
- Symbolism: Wisdom, clarity, and divine protection.
- Metaphysical Properties: Blue Zircon is believed to enhance mental clarity, promote spiritual insight, and provide emotional balance.
- Cultural Beliefs: In ancient times, Zircon was believed to be a gift from the gods, and it was used in meditative and divinatory practices.
Blue Topaz
- Symbolism: Calmness, serenity, and clarity.
- Metaphysical Properties: Blue Topaz is associated with inner peace, mental clarity, and emotional stability. It is also believed to attract love and friendship.
- Cultural Beliefs: In Greek mythology, Topaz was believed to be a stone of strength and protection, and it was used by warriors for courage and clarity in battle.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of December birthstones, especially for those with lower hardness or cleavage.
Turquoise
- Cleaning: Use mild soap and warm water with a soft cloth or brush. Avoid ultrasonic or steam cleaners, as they can damage the porous structure.
- Storage: Store separately to avoid scratching, and avoid exposure to heat, chemicals, or prolonged sunlight, which can cause fading or cracking.
Tanzanite
- Cleaning: Use mild soap and water. Avoid harsh chemicals or ultrasonic cleaners, as they can damage the surface or internal structure.
- Storage: Store in a soft pouch or box to prevent chipping or scratching.
Blue Zircon
- Cleaning: Use warm soapy water and a soft cloth. Avoid exposure to heat, as it can alter the color.
- Storage: Store separately to avoid scratching, especially from harder gemstones.
Blue Topaz
- Cleaning: Can be cleaned with warm soapy water, ultrasonic, or steam cleaners.
- Storage: Blue Topaz is very durable, so it can be stored with other gemstones, but it's still best to keep it in a soft pouch for extra protection.
Conclusion
The December birthstones—Turquoise, Tanzanite, Blue Zircon, and Blue Topaz—represent a rich tapestry of history, culture, and science. Each gemstone has its own unique properties, symbolism, and significance, making them ideal for personal adornment, spiritual use, and collecting.
For Sagittarians and December-born individuals, these stones offer not only beauty and elegance, but also protection, wisdom, and transformation. Whether worn as jewelry, used in meditation, or simply admired for their natural beauty, these gemstones are a celebration of the end of the year and the beginning of new possibilities.
Understanding the scientific and cultural background of these gemstones enhances their meaning and value, allowing wearers to connect more deeply with their birthstone and zodiac sign. As you explore these stones, you may find that one resonates with you more than the others—that is the true magic of birthstones.