December is a month defined by contrasts—the crisp chill of winter, the deep hues of the twilight sky, and the celebration of renewal. For those born in this final month of the year, nature offers a distinct spectrum of gemstones that mirror these seasonal characteristics. Unlike most months, which are traditionally linked to a single gem, December is unique in its association with multiple stones. This abundance offers a variety of choices, ranging from the ancient, opaque tranquility of Turquoise to the vivid, violet-blue fire of Tanzanite and the brilliant sparkle of Zircon.
The official birthstones for December are Turquoise, Tanzanite, and Zircon. Each of these gems possesses a unique geological history, a distinct set of physical properties, and a rich tapestry of cultural lore. While they differ significantly in structure and durability, they are united by a color palette that dominates the cool end of the spectrum—shades of blue, violet, and greenish-blue that evoke the serenity and wisdom often attributed to those born under the zodiac signs of Sagittarius and Capricorn. This article explores the geological origins, gemological properties, and historical significance of these three captivating December birthstones.
The Historical Anchor: Turquoise
Turquoise stands as the traditional bedrock of December’s birthstone list. Its name provides a clue to its ancient trade routes; the word "Turquoise" is derived from the French pierre turquoise, meaning "stone of Turkey." This nomenclature arose because the stone was introduced to Europe through Turkish bazaars, having traveled from its primary sources in the East.
Culturally, Turquoise is perhaps the most storied of the three. It is recognized as a sacred stone in many cultures throughout history. Its significance is deeply rooted in concepts of protection, truth, and calmness. Historically, it was believed to be a talisman that offered good fortune and friendship to the wearer. The spiritual meaning attached to Turquoise is one of protection and the preservation of tranquility, making it a fitting symbol for the end of the year.
The gem itself is a phosphate mineral, distinct from the silicate nature of Tanzanite and Zircon. Its formation is a geological process involving groundwater containing copper that seeps into bedrock. Over time, reactions with other minerals create an opaque stone ranging from sky blue to greenish-blue. The distinctive dark lines and shapes often seen within the stone, known as matrix, are remnants of the surrounding rock, serving as a natural fingerprint of the gem’s geological environment.
The Modern Sensation: Tanzanite
While Turquoise has held its title for centuries, Tanzanite is a relatively new addition to the gemological world, bringing a fresh, vibrant energy to the December lineup. Discovered in the 20th century, Tanzanite was added to the official birthstone list in 2002 by the Jewelry Industry Council of America, expanding the options available to December babies.
Tanzanite is singular in its origin. It is the rarest of the December stones, mined exclusively in a specific, small region of Tanzania, which gives the gem its name. This extreme rarity contributes to its high value and desirability. It is often cited as the most valuable of the December birthstones, commanding higher prices due to its limited supply and intense color.
Gemologically, Tanzanite is a variety of the mineral zoisite. Its most striking feature is its pleochroism—the ability to display different colors when viewed from different angles. Typically, it appears a rich violet-blue, a color that seems to shift and play in the light. This dynamic quality, combined with its deep, regal hue, has made it a favorite in modern jewelry design. It symbolizes transformation and new beginnings, themes that resonate powerfully with the start of a new year.
The Sparkling Traditionalist: Zircon
Completing the trio is Zircon, a gem that often suffers from confusion due to its similarity in name to the synthetic cubic zirconia. However, natural Zircon is a distinct, ancient, and naturally occurring gemstone that boasts exceptional brilliance and fire. It is the traditional alternative birthstone for December and was officially added to the birthstone list in 1952.
Zircon is a silicate mineral and is actually the oldest mineral on Earth, with some specimens dating back over 4 billion years. This ancient lineage gives it a profound connection to the history of our planet. In terms of appearance, Zircon is prized for its high refractive index, which gives it a sparkle that can rival that of a diamond. While it occurs in a variety of colors, the bright, clear blue variety is the one associated with December.
Zircon is associated with wisdom, clarity, and a sense of balance. It is believed to help organize the mind and thoughts, making it a stone for those seeking mental clarity. Despite its hardness (ranging from 6.5 to 7.5 on the Mohs scale), it has perfect cleavage in two directions, making it somewhat brittle and requiring careful handling during the cutting process and in jewelry settings.
Geological Formation and Sources
The origins of these stones are as varied as their appearances, reflecting the diverse geological processes that shape our planet.
Turquoise is a secondary mineral formed in arid regions where acidic, copper-rich water seeps into the ground and reacts with aluminum-bearing rocks. This process, known as percolation, can take millions of years. Major sources for high-quality Turquoise include Iran, the United States (particularly the Southwest), Tibet, and India. The specific mineral composition of the host rock determines the color and matrix pattern of the resulting gem.
Tanzanite has a very specific and exclusive origin. It is found only in the Merelani Hills of northern Tanzania. Geologically, it formed during a massive tectonic event—the uplift of the East African Rift—which subjected the surrounding rocks to intense heat and pressure, transforming the greenish-brown zoisite into the vivid blue-violet gem we know today. This unique geological event has not occurred anywhere else on Earth, cementing Tanzanite’s status as a true rarity.
Zircon is a common mineral found in igneous and metamorphic rocks. It is highly resistant to weathering and is often found in sedimentary deposits as well. While found in many parts of the world, including Australia, Sri Lanka, and the United States, the heat-treated blue zircon used in jewelry often originates from Cambodia and Thailand. The transformation of zircon into its brilliant blue form is usually achieved through heat treatment, which removes brownish tones and enhances the stone's natural clarity and color.
Gemological Properties
Understanding the physical characteristics of these stones is crucial for both jewelers and consumers, particularly regarding durability and care.
| Gemstone | Mineral Group | Mohs Hardness | Chemical Composition | Key Visual Characteristics |
|---|---|---|---|---|
| Turquoise | Phosphate | 5 – 6 | Hydrated copper/aluminum phosphate | Opaque, often with a matrix (web-like patterns), sky blue to greenish-blue. |
| Tanzanite | Zoisite (Silicate) | 6.5 – 7 | Calcium aluminum hydroxyl sorosilicate | Transparent, pleochroic (violet-blue), often eye-clean. |
| Zircon | Zirconium Silicate | 6.5 – 7.5 | ZrSiO₄ | High refractive index (brilliant sparkle), typically bright blue, can have high clarity. |
| Blue Topaz | Silicate | 8 | Al₂(F,OH)₂SiO₄ | Transparent, glass-like luster, ranges from light sky blue to deep London blue. |
Note: While Blue Topaz is often included in modern lists of December birthstones, the primary trio recognized by traditional and gemological authorities remains Turquoise, Tanzanite, and Zircon.
Hardness and Durability: The most significant difference among the stones is their hardness, which dictates their suitability for different types of jewelry. * Turquoise, with a hardness of only 5 to 6, is the softest of the group. It is susceptible to scratching and can be damaged by acids, lotions, and heat. It requires gentle handling and is best suited for pieces that are not subjected to daily wear and tear, such as pendants or earrings. * Tanzanite and Zircon are moderately hard (6.5 to 7.5) but possess different structural weaknesses. Zircon has perfect cleavage, meaning it can split along internal planes if struck with force. Tanzanite, while generally stable, can be brittle and may also exhibit cleavage. Both are more durable than Turquoise but should still be protected from hard blows. * Blue Topaz, which appears in some modern lists, has a hardness of 8, making it the most durable option for everyday wear among the blue December stones.
Color and Treatment: The blue coloration central to all December stones has different origins. * Turquoise’s color is natural, derived from its copper content. * Tanzanite’s natural color ranges from brown to greenish-blue, but it is almost always heated to achieve the prized violet-blue hue. * Zircon’s blue color is typically the result of heat treatment applied to brown zircon crystals. * Blue Topaz, including varieties like Sky Blue, Swiss Blue, and London Blue, is almost always produced by irradiating and heating naturally colorless topaz. This is an industry-standard practice that creates the deep, saturated blues for which the stone is known.
Care and Cleaning
Proper maintenance is essential to preserve the beauty of December birthstones, and the care required varies significantly by gem.
Turquoise Care: Due to its porosity and low hardness, Turquoise is sensitive to chemicals. It should never be cleaned with ultrasonic cleaners or steam. Cleaning should be done gently with warm, soapy water and a soft cloth. It is advisable to apply cosmetics, perfumes, and hair sprays before putting on Turquoise jewelry to avoid exposure to harsh chemicals that can discolor or damage the stone.
Tanzanite Care: Tanzanite can be cleaned with warm, soapy water and a soft brush. It is generally stable but should be kept away from sudden temperature changes to prevent fracturing. As with all fine gems, it is best to store Tanzanite pieces separately to avoid scratching by harder stones.
Zircon Care: Zircon can be cleaned with warm, soapy water and a soft brush. While it is relatively hard, its cleavage planes make it vulnerable to impact. It should be stored carefully, ideally in a fabric-lined box, and kept away from harder gems like diamonds and sapphires. Avoid ultrasonic cleaners, as the vibrations could potentially damage the stone along its cleavage planes.
Blue Topaz Care: Blue Topaz is generally stable under normal conditions. It can be cleaned with warm, soapy water and a soft brush. However, prolonged exposure to strong sunlight or heat can sometimes cause fading in certain treated blue topazes, so it is wise to store it away from direct light when not being worn.
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, these stones carry a weight of symbolism that has been passed down through generations.
Turquoise is universally recognized as a stone of protection. It was traditionally worn by warriors and travelers to ward off injury and evil. It is also associated with friendship and good fortune, making it a popular gift among friends. Spiritually, it is believed to align all the chakras, providing a sense of balance and grounding.
Tanzanite, as a newer gem, has quickly developed its own lore. It is often associated with transformation, encouraging the wearer to embrace change and embark on new beginnings. Its striking color is linked to the higher mind and spiritual awakening, helping to bridge the gap between the conscious and subconscious.
Zircon is a stone of purity, clarity, and wisdom. It is believed to help with spiritual grounding and to promote honor and purity in one's actions. Historically, it was also thought to aid in sleep and bring prosperity to its owner.
Conclusion
The birthstones of December offer a remarkable range of choices, each with its own distinct identity. Turquoise provides a connection to ancient traditions and the earth, with its opaque, calming blue-green hues. Tanzanite brings a modern, vibrant, and exclusive allure, its shifting violet tones symbolizing a new era in gemology. Zircon offers timeless brilliance and a link to the very origins of our planet, sparkling with a fire that rivals the most celebrated gems.
For the individual born in December, the selection of a birthstone is not merely a matter of color preference but a choice of character and connection. Whether one is drawn to the protective history of Turquoise, the transformative energy of Tanzanite, or the clarifying brilliance of Zircon, these gems perfectly encapsulate the cool elegance and profound depth of the year’s final month. Their durability varies, requiring thoughtful care, but their beauty and symbolic weight ensure they remain cherished treasures for generations.