December 19th occupies a unique place in the birthstone calendar, distinguished by its association with not one, but three officially recognized gemstones: tanzanite, turquoise, and zircon. This triad offers a remarkable spectrum of colors, histories, and properties, making it one of the most versatile and meaningful birthstone selections. While turquoise holds the distinction of being the traditional and earliest recognized December stone, the modern list has expanded to include the vivid blue-violet tanzanite and the brilliant, fire-filled zircon. Together, these stones represent a journey through time—from ancient civilizations to a 20th-century African discovery—and provide a rich tapestry of symbolism and gemological wonder for those born on this date. This article delves into the history, geological origins, physical properties, and cultural significance of these three remarkable gems, offering a comprehensive guide for enthusiasts, collectors, and anyone drawn to their unique allure.
The Evolution of December's Birthstones
The concept of assigning gemstones to birth months is a practice with deep historical roots, though its modern form is a relatively recent development. The earliest known connection between gemstones and specific groups comes from the Biblical Book of Exodus, which describes 12 gemstones set in the breastplate of Aaron, each representing one of the twelve tribes of Israel. It is important to note that this ancient list did not assign stones to calendar months but to tribes or people.
The formalization of birthstones by month began to take shape in the 19th century. In 1870, the renowned jewelry house Tiffany & Co. published the first American version of a birthstone list, which notably included turquoise for the month of December. This list provided a foundational reference for the American jewelry trade and public.
The list continued to evolve through standardization efforts by industry bodies. In 1912, the National Association of Jewellers (now the American Gem Trade Association) issued a more formalized list. This version expanded the December options by introducing lapis lazuli as an alternative to turquoise. The following decades saw further additions. In 1952, zircon was officially added to the list of December birthstones. The most recent addition occurred in 2002, when tanzanite was introduced as the third modern December birthstone.
The inclusion of multiple stones for a single month, particularly December, reflects a desire to offer a wider range of choices in terms of color, price, and personal meaning. For those born on December 19th, this selection is especially significant, as it encompasses a traditional ancient stone (turquoise), a geologically ancient but recently popularized gem (zircon), and a modern marvel of the gem world (tanzanite).
Tanzanite: A Modern Marvel from the Merelani Hills
Origin and Discovery
Tanzanite is the youngest of the modern birthstones, a gem that has captivated the world for less than six decades. Its story began in 1967 near the base of Mount Kilimanjaro in Tanzania, specifically in the Merelani Hills of the Manyara Region. The gemstone was initially discovered as a rough, violet-colored rock. Prospectors and geologists quickly recognized its potential, realizing that the stone could be heat-treated to transform its color from a brownish-violet to the desirable, intense blue-to-violet hues for which it is now famous. This discovery was singular; to date, tanzanite is found in only one known location in the world, making it exponentially rarer than diamond. This geographic singularity has led many to describe it as a "geological phenomenon."
Gemological Properties
Tanzanite is a variety of the mineral zoisite. Its most striking characteristic is its strong pleochroism, a property where the gem shows different colors when viewed from different crystallographic directions. From one angle, it may display a deep blue, while from another, it may show a violet or reddish hue. This trichroic nature (showing three distinct colors) is a key identifier for the gem.
The heat treatment it undergoes is a standard and accepted practice in the gem trade. Heating the rough material to temperatures of around 600 degrees Celsius for a few hours is sufficient to remove the brownish tints and enhance the blue-violet color. This process is permanent and stable, and treated tanzanite is considered the norm in the market. Regarding its physical durability, tanzanite has a Mohs hardness of 6.5 to 7, which makes it relatively durable but susceptible to scratching and chipping if handled roughly. It has perfect cleavage in one direction, meaning it can split along a plane if struck with sufficient force, requiring careful setting and handling in jewelry.
Symbolism and Lore
Despite its recent introduction to the gemological world, tanzanite has quickly accumulated a rich layer of symbolism. It is often associated with spiritual growth, transformation, and the opening of the third eye or higher consciousness. Its unique color, which bridges the calm of blue and the energy of violet, is said to promote emotional balance and clear communication. For those born on December 19th, tanzanite is believed to offer a connection to one's higher purpose and facilitate a journey of self-discovery and success.
Turquoise: An Ancient Stone of Protection and Wisdom
Historical Significance
Turquoise is one of the oldest gemstones known to humanity, with a history spanning thousands of years and multiple continents. Its use predates recorded history, with archaeological evidence pointing to its mining and use in ancient Egypt, Persia, and the Americas. In Egypt, turquoise was used for intricate jewelry, amulets, and funeral objects, symbolizing rebirth and protection in the afterlife. The stone's name itself derives from the French pierre turquoise, meaning "Turkish stone," as it was brought to Europe from Turkey via Persian trade routes.
In the Americas, turquoise holds profound importance in Native American cultures, particularly among the Navajo, Zuni, and Pueblo peoples. For these cultures, the stone is not merely decorative but sacred, representing the sky, water, and earth. It is used in ceremonial objects, jewelry, and as a medium for spiritual connection. Turquoise was one of the first gemstones to be recognized in the modern birthstone lists, included in Tiffany & Co.'s 1870 publication, and has remained a staple of December's gems ever since.
Geological Formation and Sources
Turquoise is a secondary mineral that forms in arid regions where acidic, copper-rich water percolates through aluminum- and phosphorus-bearing rocks, such as weathered volcanic or sedimentary formations. This process occurs over millions of years, resulting in the deposition of copper aluminum phosphate with water, giving turquoise its characteristic blue-green color. The presence of iron can shift the color toward green, while the presence of zinc can create a yellowish hue.
Major sources of turquoise include the United States (notably Arizona, New Mexico, and Nevada), Iran (historically the source of the finest "Persian turquoise"), China, and Egypt. American turquoise, especially from the Southwest, is highly prized for its matrix patterns—the vein-like inclusions of the host rock that create unique "spiderweb" or other patterns within the stone.
Gemological Properties and Care
Turquoise has a Mohs hardness of 5 to 6, making it relatively soft and porous. It is often treated with wax or oil to fill surface pores, enhance its color, and improve its durability. This porosity means it is susceptible to discoloration from chemicals, cosmetics, and even the oils in human skin. Proper care is essential: it should be cleaned with warm water and a mild soap, using a soft cloth. Avoid ultrasonic cleaners, steam cleaners, and harsh chemicals. Storing turquoise separately from harder gemstones will prevent scratches.
Symbolism and Lore
The metaphysical beliefs surrounding turquoise are as ancient as the stone itself. It is universally regarded as a stone of protection, believed to ward off negative energy and bring safety to travelers. It is also associated with healing, wisdom, and emotional balance. In many cultures, it is considered a conduit for communication with the spiritual world and a bringer of good fortune. For the December 19th individual, turquoise offers a connection to ancient wisdom, grounding energy, and a sense of serene protection.
Zircon: The Fire of Ancient Earth
Historical and Geological Context
Zircon is one of the oldest minerals on Earth, with some zircon crystals dating back over 4 billion years, making them crucial for understanding the planet's early history. Despite its ancient origins, blue zircon was added to the official birthstone list only in 1952. It is important to distinguish zircon from the synthetic material "cubic zirconia" (CZ), which is a diamond simulant. Natural zircon is a distinct and valuable gemstone in its own right.
Zircon forms in igneous and metamorphic rocks. The most prized blue zircon is typically heat-treated to enhance its color from brownish or greenish hues to a desirable sky blue. This heat treatment is standard and permanent, similar to the process used for tanzanite.
Gemological Properties
Zircon is renowned for its exceptional brilliance and fire, which can rival that of diamond. It has a refractive index higher than most colored gemstones, which contributes to its dazzling light performance. On the Mohs scale, zircon has a hardness of 6.5 to 7.5, making it durable enough for most jewelry, though it can be brittle due to its perfect cleavage in two directions. This cleavage requires skilled cutting and setting to avoid damage.
The most valued color for birthstone zircon is a vibrant, clear blue, though it can also be found in yellow, green, red, and brown. The blue variety is specifically referenced in the context of December birthstones.
Symbolism and Lore
Zircon is associated with intuition, creativity, and motivation. Its brilliant fire is said to stimulate mental clarity and aid in the pursuit of goals. In some traditions, it is believed to promote spiritual grounding while fostering inspiration and joy. For those born on December 19th, zircon is thought to provide a boost of energy and creative insight, helping to turn ideas into reality.
Comparative Gemological Properties
The three December 19th birthstones differ significantly in their physical characteristics, which influences their use in jewelry and care requirements. The following table summarizes key properties based on the information derived from the provided sources.
| Gemstone | Mineral Family | Typical Color | Mohs Hardness | Key Property | Care Considerations |
|---|---|---|---|---|---|
| Tanzanite | Zoisite | Blue to Violet | 6.5 - 7 | Strong Pleochroism | Avoid blows and scratches; store separately. |
| Turquoise | Phosphate | Blue to Green | 5 - 6 | Porous, often with matrix | Avoid chemicals and heat; clean with mild soap only. |
| Zircon | Zircon (Silicate) | Blue (most prized) | 6.5 - 7.5 | High Brilliance & Fire | Avoid blows due to cleavage; store separately. |
Care and Maintenance for Longevity
Given their varied properties, proper care is essential to preserve the beauty of these gems.
- Tanzanite: Due to its hardness and perfect cleavage, tanzanite should be protected from hard impacts. It is best suited for jewelry worn on less active occasions, such as pendants or earrings, rather than rings subject to daily wear. Cleaning can be done with warm, soapy water and a soft brush. Ultrasonic and steam cleaners are not recommended.
- Turquoise: As a soft and porous stone, turquoise requires the most diligent care. It should be the last item put on when dressing and the first removed. Avoid exposure to lotions, perfumes, hairsprays, and other chemicals. Clean only with a soft, dry cloth. If necessary, use a damp cloth with mild soap, but dry immediately. Never use an ultrasonic cleaner.
- Zircon: While relatively hard, zircon's cleavage makes it susceptible to chipping if struck. It is best set in protective settings like bezels. It is generally not sensitive to light or heat, making it more forgiving in terms of care. It can be cleaned with warm water, mild soap, and a soft brush. Store it separately from other jewelry to prevent scratches.
Conclusion
The birthstones for December 19th—tanzanite, turquoise, and zircon—form a compelling triad that spans the breadth of gemological history and human culture. From the ancient, protective talisman of turquoise to the billion-year-old yet newly popularized zircon, and the modern geological wonder of tanzanite, each stone offers a unique narrative. They differ in hardness, color, and origin, yet they are united by their official designation for this date and their profound symbolic meanings. For individuals born on December 19th, this collection provides not just a choice of beautiful jewelry but a connection to spiritual growth, ancient wisdom, and creative inspiration. Understanding their distinct properties and histories allows for a deeper appreciation of these gems, ensuring they can be cherished and preserved for generations to come.