The final month of the year offers a remarkable diversity of birthstones, providing those born in December a rich palette of colors, histories, and properties from which to choose. While traditional lists often highlight Turquoise and Zircon, modern additions like Tanzanite and Blue Topaz have expanded the options considerably. These gems, ranging from the ancient sky-blue of Turquoise to the vibrant violet of Tanzanite, are united by their connection to the winter month, yet each possesses a unique geological origin, cultural significance, and set of gemological characteristics. This guide explores the complete spectrum of December’s birthstones, delving into their history, formation, scientific properties, and the lore that has made them treasured across millennia.
History and Lore
The historical narrative of December’s birthstones is as varied as the gems themselves, weaving through ancient civilizations, royal courts, and religious traditions.
Turquoise, perhaps the most ancient of the group, derives its name from the French pierre turquoise, meaning "Turkish stone," a reference to the trade routes through which it reached Europe from its origins in Persia and the Sinai Peninsula. Its use as an amulet dates back thousands of years. It was prized for its perceived ability to protect the wearer from danger and was often used by lovers and married couples to safeguard their relationships and preserve friendship. A notable belief was that the stone could warn of impending illness or danger by changing its color to pale. In Tibet, turquoise was considered a birthstone of fortune, health, and success, and was even used as a form of currency. For ancient Incas, Mayas, and Native American tribes of the Southwest, the gem was a symbol of youth, strength, and a conduit to the divine, often offered as a gift to gods.
Zircon, though often confused with the synthetic cubic zirconia, is one of the oldest minerals on Earth, with some specimens dating back billions of years. Its name is believed to be derived from the Persian zargun, meaning "gold-colored," though it is most famous today in its brilliant blue form. Historically, zircon was a protective talisman, believed to aid in restful sleep and ward off evil spirits. It was also a stone of honor and purity, often associated with wisdom and prosperity.
Tanzanite is a relative newcomer to the gemological world. Discovered in the Merelani Hills of Tanzania in the 1960s, its vibrant violet-blue hue quickly captured the market. The Maasai people of the region hold the stone in high regard, associating it with a vibrant life and spiritual enlightenment. Its rapid rise to prominence was famously cemented when it was mentioned as a gift from Jay Z to Beyoncé, adding a modern celebrity allure to its history.
Blue Topaz, while topaz itself has been known since antiquity, owes its status as a mainstream December birthstone to modern gemstone treatments. Naturally occurring blue topaz is rare; the vivid blues seen in jewelry today are typically the result of irradiation and heat treatment of colorless topaz. This process has made beautiful blue topaz widely accessible, leading to its inclusion on many modern birthstone lists. It is often associated with clarity of thought and communication.
Finally, Sapphire, while more commonly associated with September, is listed in some traditional and astrological charts as a special apostle birthstone for all of December, linked to St. Paul. Ancient Hebrews revered it as a gem of wisdom, believing it was the stone of Joseph the Wise. It was thought to protect from evil and was a symbol of divine favor, with legends connecting it to the ring of King Solomon and the holy of holies.
Geological Formation and Sources
Understanding how these gems are formed and where they are found provides a deeper appreciation for their rarity and value.
Turquoise is a secondary mineral that forms when acidic, copper-rich water percolates through pre-existing rocks containing aluminum and phosphorus. This process occurs in arid regions, and its formation is intrinsically linked to the presence of copper deposits. Consequently, the most significant sources for turquoise have historically been in the dry climates of Persia (modern-day Iran), the Sinai Peninsula, and the Southwestern United States (Arizona, New Mexico, Nevada). The gem is often found in veins or nodules within a host rock, such as limonite or sandstone, which can create the characteristic "matrix" or spiderweb patterns seen in some specimens.
Zircon is a mineral belonging to the nesosilicates group. It is a primary mineral, meaning it crystallizes directly from magma as it cools to form igneous and metamorphic rocks. Due to its exceptional durability, it can survive for billions of years and is found in many ancient rocks around the world. Significant sources for gem-quality zircon include Cambodia (for the prized "hyacinth" red variety), Sri Lanka (for a wide range of colors, including the famous blue), Thailand, Australia, and the United States.
Tanzanite is a variety of the mineral zoisite and is found in only one location on Earth: the Merelani Hills of Northern Tanzania, near the base of Mount Kilimanjaro. Its formation is unique, believed to have occurred between 585 and 590 million years ago when a massive tectonic event caused intense heat and pressure, transforming the existing zoisite into the vibrant blue-violet crystals we see today. The limited geographic area of its source adds to its rarity and allure.
Blue Topaz is a silicate mineral with the chemical formula Al₂SiO₄(F,OH)₂. It crystallizes from silica-rich magmatic fluids in cavities and veins of igneous rocks like granite and rhyolite. While topaz is found in many locations, including Brazil, Sri Lanka, and the U.S., the vast majority of the intensely blue topaz on the market begins as colorless or pale topaz. The brilliant blue is achieved through a process of irradiation followed by controlled heating, which alters the crystal's color centers.
Sapphire is a variety of the mineral corundum (aluminum oxide, Al₂O₃), with trace elements like iron and titanium responsible for its blue color. It forms under high-temperature and high-pressure conditions in metamorphic rocks, such as gneiss and schist, or in certain igneous rocks like basalt. Major sources for sapphire include Sri Lanka, Kashmir (India), Myanmar, Thailand, and Australia.
Gemological Properties
The physical and chemical characteristics of each gemstone determine its appearance, durability, and value. The following table summarizes the key properties of December's primary birthstones.
| Gemstone | Mineral Family | Chemical Composition | Mohs Hardness | Crystal System | Key Characteristics |
|---|---|---|---|---|---|
| Turquoise | Phosphate | CuAl₆(PO₄)₄(OH)₈·4H₂O | 5 - 6 | Triclinic | Opaque, color ranges from green to blue, often has a matrix. |
| Zircon | Nesosilicate | ZrSiO₄ | 6.5 - 7.5 | Tetragonal | High refractive index, strong dispersion ("fire"), can be radioactive. |
| Tanzanite | Epidote | Ca₂Al₃(SiO₄)₃(OH) | 6 - 7 | Orthorhombic | Pleochroic (shows blue, violet, and burgundy), trichroic. |
| Blue Topaz | Silicate | Al₂SiO₄(F,OH)₂ | 8 | Orthorhombic | Often treated for color, good clarity, can be cleaved. |
| Sapphire | Corundum | Al₂O₃ | 9 | Trigonal | Extremely durable, can be found in various colors (except red). |
Turquoise is relatively soft and porous compared to other gems, with a hardness of 5 to 6 on the Mohs scale. This porosity means it can absorb oils and chemicals, which can alter its color over time. Its chemical composition includes water and copper, which gives it its signature blue-green hue.
Zircon should not be confused with cubic zirconia. It is a natural gem with a high refractive index, giving it exceptional brilliance and fire, sometimes even exceeding that of a diamond. Its hardness ranges from 6.5 to 7.5, making it suitable for jewelry, though it can be brittle. Some zircon contains trace amounts of uranium and thorium, which can make it radioactive; this type of zircon is often heat-treated to improve its color and clarity.
Tanzanite has a hardness of 6 to 7. Its most famous gemological feature is its strong pleochroism—the ability to show different colors when viewed from different angles. Fine tanzanite typically displays a deep blue along one crystal axis and a vibrant violet-purple along another. This property is critical for gem cutters, who must orient the stone carefully to display the most desirable color.
Blue Topaz is one of the hardest of the December stones, with a rating of 8 on the Mohs scale, making it very durable for everyday wear. However, it possesses perfect cleavage in one direction, meaning it can be chipped or split by a sharp blow. The intense blue color of most commercial topaz is a result of treatment, a fact that is important for consumers to understand.
Sapphire is the most durable of all the December-associated stones, with a Mohs hardness of 9, second only to diamond. This exceptional hardness, combined with its vitreous luster and strong pleochroism, makes it a premier gemstone. Its chemical purity (aluminum oxide) and the trace elements that cause its color make it one of the most stable and enduring gems.
Symbolism and Metaphysical Beliefs
Across cultures and centuries, gemstones have been imbued with symbolic meanings and perceived metaphysical powers. December’s birthstones are particularly rich in such lore.
- Turquoise is widely regarded as a master healer and a stone of protection. It is believed to promote inner calm, tranquility, and spiritual grounding. Many cultures associate it with positive energy, luck, and prosperity. For Native American tribes, it is a sacred stone connecting the wearer to the earth and sky.
- Zircon is known as a stone of purity, clarity, and wisdom. It is believed to aid in spiritual grounding and to help its wearer achieve their goals with honor and integrity. Some traditions hold that zircon promotes restful sleep and wards off nightmares.
- Tanzanite, with its extraordinary color, is associated with spiritual awakening and higher consciousness. It is said to stimulate the throat chakra, enhancing communication and self-expression. Its energy is often described as transformative, encouraging a break from old habits and a move toward a more authentic life.
- Blue Topaz is linked to clarity of thought, calmness, and emotional balance. It is believed to be a stone of communication, helping to express one’s thoughts and feelings clearly and compassionately. It is also associated with truth and forgiveness.
- Sapphire has long been a symbol of wisdom, loyalty, and nobility. It is believed to bring peace of mind and spiritual insight, and to protect the wearer from envy and harm. Ancient and medieval traditions credited sapphire with the power to attract divine favor and to cure ailments of the eye.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of any piece of jewelry. The varying hardness and chemical composition of December’s birthstones require specific attention.
- Turquoise: Due to its porosity, turquoise is susceptible to damage from chemicals, cosmetics, and even skin oils. It should be cleaned with warm water, a mild soap, and a soft cloth. Avoid ultrasonic cleaners, steam cleaners, and harsh chemicals. Store it separately to prevent scratching.
- Zircon: While fairly hard, zircon can be brittle. Avoid rough handling and exposure to extreme temperature changes, which can cause fractures. The best method for cleaning is warm, soapy water and a soft brush. Avoid ultrasonic cleaners.
- Tanzanite: With a hardness of 6-7, tanzanite is more susceptible to scratching than harder gems. It is also sensitive to sharp blows due to its cleavage. Clean with warm, soapy water and a soft brush. Avoid ultrasonic and steam cleaners.
- Blue Topaz: As a relatively hard and durable stone, topaz can handle daily wear but is vulnerable to chipping along its cleavage planes. It can be safely cleaned with warm, soapy water and a soft brush. Ultrasonic cleaners are generally safe, but steam cleaning is not recommended due to potential thermal shock.
- Sapphire: The most durable of the group, sapphire is excellent for everyday wear. It can be cleaned using almost any method: warm, soapy water, ultrasonic cleaners, and steam cleaners are all generally safe, provided the stone has no fractures or treatments that could be affected by heat.
Conclusion
December’s birthstones offer an unparalleled selection for those born in the last month of the year. From the ancient, protective allure of Turquoise and the brilliant fire of Zircon to the modern, vibrant appeal of Tanzanite and the accessible beauty of Blue Topaz, each gem tells a unique story of geological formation and human history. For those seeking ultimate durability and timeless symbolism, Sapphire remains a powerful, traditional choice. This diverse collection ensures that every December-born individual can find a gemstone that not only reflects their personal style but also connects them to a rich tapestry of cultural lore and scientific wonder.