The final month of the year is uniquely represented not by a single gem, but by a trio of distinct blue stones: Turquoise, Zircon, and Tanzanite. Each offers a different interpretation of the color blue, ranging from the earthy, opaque greens of turquoise to the fiery, clear brilliance of zircon and the velvety violet-blues of tanzanite. This multiplicity provides those born in December with a diverse palette of options, allowing for personal expression through color, durability, and history.
The modern list of December birthstones has evolved significantly over the last century, driven by commercial interests and the discovery of new deposits. While turquoise has been cherished for millennia, the addition of zircon in 1952 and tanzanite in 2002 reflects the jewelry industry's desire to offer variety and affordability. Beyond their aesthetic appeal, these stones are steeped in lore, believed by ancient civilizations to possess powers ranging from protection against physical harm to the ability to attract immense wealth. This article explores the geological origins, gemological properties, and historical significance of December's three primary birthstones.
History and Lore: The Ancient Lineage of December’s Gems
The history of December's birthstones is a tale of two distinct eras: the ancient reverence for turquoise and the relatively recent commercial adoption of zircon and tanzanite.
The Ancient Pedigree of Turquoise
Among the three, Turquoise holds the undisputed title of historical longevity. It is a gem that has been "cherished for millennia," finding its way into the adornments of the most powerful rulers of antiquity. In ancient Egypt, pharaohs and other elite figures wore turquoise extensively, integrating the stone into their burial rites and royal regalia. The reverence for the stone was not limited to the Nile Valley; Chinese artisans were carving turquoise more than 3,000 years ago, indicating a sophisticated trade network and cultural appreciation for the material long before the Common Era.
The stone’s name itself offers a glimpse into the complex trade routes of the medieval world. The term "turquoise" is derived from the French phrase pierre turquoise, meaning "Turkish stone." This nomenclature arose because the gem was first brought to Europe through Turkish bazaars, having originated from mining sources in Persia (modern-day Iran). While the physical origin was Persian, the commercial path through Turkey gave the stone its enduring name in Western languages.
The metaphysical beliefs surrounding turquoise are as colorful as the stone itself. Across cultures, it was viewed as a talisman of protection and good fortune. By the 13th century, a specific superstition held that turquoise could protect the wearer from falling, particularly from horses. It was believed that the stone would physically shatter or break into several pieces when disaster was imminent, serving as a physical warning to the wearer. Hindu mystics attached a different power to the stone; they maintained that viewing a turquoise immediately after beholding the new moon would ensure "fantastic wealth."
In the Americas, turquoise held a sacred place in Native American culture. The Apache tribe believed that turquoise could be found by following a rainbow to its end, linking the stone to celestial phenomena and divine luck. For these tribes, as for many others, the stone was not merely decorative but a conduit for spiritual connection and protection.
The Modern Adoption of Zircon and Tanzanite
Unlike the ancient lineage of turquoise, Zircon and Tanzanite are relatively new entrants to the standardized birthstone list. The modern concept of birthstones was largely standardized in 1912 by the National Association of Jewelers, which sought to combine traditional customs with gemstones that were practical for jewelry companies to sell. At that time, turquoise was the primary birthstone for December.
It was not until 1952 that the Jewelry Industry Council of America updated the list, adding Zircon to December’s options. This addition was likely driven by the gem's availability and its desirable fire and brilliance, which offered a sparkling alternative to the opaque turquoise. Zircon is often confused with the synthetic cubic zirconia, but it is a natural gemstone with a long geological history, distinct from the lab-created simulant.
The most recent addition to the December family is Tanzanite, which was added to the official list in 2002. The discovery of this stone is a modern gemological phenomenon. Found in only one location on Earth—the Merelani Hills of northern Tanzania—tanzanite was introduced to the market in the late 1960s. Its rapid ascent to birthstone status highlights the dynamic nature of the jewelry industry, where new discoveries can quickly reshape tradition.
Geological Formation and Sources
The three December stones differ significantly in how they are formed and where they are found, ranging from widespread secondary deposits to a single, geologically unique occurrence.
Turquoise: A Secondary Mineral
Turquoise is a secondary mineral that forms when water containing dissolved copper and aluminum seeps through pre-existing rocks. It typically develops in arid or semi-arid environments near water tables. The chemical composition of the surrounding rock dictates the stone's final color; copper produces the prized sky blue tones, while iron is responsible for shifting the color toward green. The stone is often found with veins or a "matrix" of the host rock running through it, which are remnants of the rock in which it formed. Because of this formation process, turquoise deposits are found worldwide, making it a globally accessible gemstone.
Zircon: A Detrital Gem
Zircon is a mineral that forms during the crystallization of magma. Over geological time, these crystals are eroded from their primary source rocks and deposited as detrital grains in sedimentary environments. Significant sources for gem-quality zircon include Sri Lanka, Cambodia, and Australia. Because it is highly resistant to weathering, zircon is often found in placer deposits, similar to diamonds and sapphires.
Tanzanite: The Singular Occurrence
Tanzanite is the rarest of the three, owing its existence to a unique geological event. It is mined exclusively in the Merelani Hills of Tanzania. The gem is a variety of the mineral zoisite and gets its vivid blue-violet color through a combination of specific geological conditions and subsequent heat treatment. Because it is found in only a single geographic area, its supply is finite, contributing to its high value and desirability.
Gemological Properties
The physical properties of these stones dictate not only their appearance but also their durability and care requirements. The following table summarizes key data derived from the provided sources:
| Property | Tanzanite | Turquoise | Zircon | Blue Topaz* |
|---|---|---|---|---|
| Natural Color | Blue to violet | Sky blue to greenish | Blue | Pale blue to dark blue |
| Mohs Hardness | 6 to 7 | 5 to 6 | 6.5 to 7.5 | 8 |
| Heat Treatment | Common | Stabilization common | Common | Common |
| Best For | Occasional rings, earrings, pendants | Earrings, pendants, beads | Earrings, pendants, and protected rings | Daily wear rings, all jewelry |
| Sensitivity | Prone to chipping | Sensitive to chemicals and moisture | Brittle at edges | Sensitive to sharp impacts |
| Care Needs | Gentle cleaning only | Very gentle, avoid all chemicals | Avoid steam and ultrasonic | Mild care, avoid sharp hits |
*Note: While Blue Topaz appears in some sources as a December option, it is not listed in the primary table of the three main stones in Source 1. However, Source 5 identifies it as the hardest of the December options (Mohs 8).
Turquoise
Turquoise is a semi-translucent to opaque gem ranging from blue to green. It has a Mohs hardness of 5 to 6, making it relatively soft compared to other jewelry stones. It is sensitive to chemicals, moisture, and heat. Oils and pigments can easily discolor the stone, and it can lose color if water is lost. Because of its porosity, turquoise is often "stabilized" (a process where the stone is impregnated with a clear resin) to improve its durability and color retention.
Zircon
Zircon is known for its high refractive index, which gives it a brilliance and fire comparable to diamond. It ranges in color from blue to various other hues. With a hardness of 6.5 to 7.5, it is durable enough for jewelry but can be brittle at the edges. Blue zircon is typically produced by heating brown zircon at high temperatures. Sources note that zircon should be protected from steam and ultrasonic cleaners to prevent damage.
Tanzanite
Tanzanite is the most fragile of the trio regarding daily wear. It has a hardness of 6 to 7 but is prone to chipping due to its crystal structure and cleavage. It is almost always heat-treated to achieve its signature blue-violet color. The sources emphasize that tanzanite is best suited for occasional wear items like earrings or pendants, rather than rings that are subject to daily impact.
Symbolism and Metaphysical Beliefs
The symbolism attached to these stones is diverse, reflecting their different cultural histories.
Turquoise is the stone of protection. It has been historically associated with health, good fortune, and happiness. It promotes positive energy and spirituality. The belief that it would break to warn of impending danger underscores its role as a guardian stone.
Zircon is associated with clarity, wisdom, and balance. In modern interpretations, it is believed to help the wearer achieve mental clarity and emotional stability. Its fiery brilliance is often linked to spiritual awakening.
Tanzanite represents transformation and new beginnings. As a relatively new gem discovered in the 20th century, it embodies modernity and the rarity of unique opportunity. It is often associated with a higher consciousness and the ability to navigate change.
Care and Cleaning
Because the December birthstones vary significantly in hardness and chemical stability, care requirements are specific to each stone.
Turquoise requires the most delicate handling. It should be cleaned only with warm, soapy water and a soft cloth. It must be kept away from all chemicals, including cosmetics, perfumes, and household cleaners, as these can permanently alter its color. It is also sensitive to prolonged exposure to water, which can cause the stone to swell or crack.
Zircon is durable but can be brittle. While it can be cleaned with warm soapy water, it should be kept away from ultrasonic cleaners and steam. Sudden temperature changes can cause fractures in zircon.
Tanzanite is best cleaned with warm soapy water and a soft brush. It should never be placed in an ultrasonic cleaner or subjected to steam, as this can cause the stone to crack or chip. Given its relative softness and cleavage, it is vital to protect tanzanite jewelry from hard knocks.
Conclusion
December's birthstones offer a remarkable range of choices, from the ancient, protective talisman of turquoise to the brilliant, fiery sparkle of zircon and the rare, transformative allure of tanzanite. While they differ in origin, hardness, and value, they are united by the color blue and a rich tapestry of history. Whether chosen for a December birthday or simply for their beauty, these stones provide a connection to both the deep past and the dynamic present of the gemological world.