Tanzanite is the most valuable of the four December birthstones. It is the rarest, since it’s only mined in a specific region of Tanzania. That’s why it’s also the most expensive. This striking blue-violet gem, officially recognized as a December birthstone in 2002, stands apart not only for its singular color but also for its geological singularity and modern metaphysical significance. While December is traditionally associated with turquoise and zircon, the addition of tanzanite has introduced a vibrant, contemporary choice that captures the imagination of collectors and jewelry enthusiasts alike. Its color, which exhibits a rich blue-violet hue that changes depending on the angle and lighting, is often compared to that of sapphire, yet it possesses a unique character all its own. This article explores the comprehensive story of tanzanite—from its recent discovery and exclusive mining location to its gemological properties, cultural symbolism, and practical care—providing a definitive guide to this extraordinary birthstone.
History and Lore: A Modern Legend with Ancient Allure
The history of tanzanite is exceptionally brief in the annals of gemology, making its rapid ascent to prominence all the more remarkable. Unlike turquoise, which has been cherished for millennia, or zircon, which has been used in jewelry for centuries, tanzanite is a product of the late 20th century. Its official discovery and subsequent introduction to the global gem market represent one of the most significant gemological events of the modern era.
Tanzanite was officially added as a precious stone for December by the American Gem Trade Association in 2002. This addition was a reflection of its growing popularity and commercial significance. The decision to include tanzanite alongside the traditional December stones of turquoise and zircon was part of a historical evolution of birthstone lists. The standardized American birthstone list, first established in 1912 by the National Association of Jewelers, has been updated several times to reflect new discoveries and market trends. In 1952, the Jewelry Industry Council of America updated the list, adding zircon to December’s options. Fifty years later, in 2002, tanzanite was officially recognized, cementing its status as a modern birthstone.
Despite its recent discovery, tanzanite has quickly developed a rich lore centered on themes of transformation and intuition. Because it is a relatively new discovery, it resonates with people who value modern spirituality and self-growth. It symbolizes transformation, new beginnings, and heightened intuition. This symbolism is particularly potent for those born in December, a month that marks the end of one year and the anticipation of another, mirroring the gemstone’s association with new chapters and personal evolution. While it lacks the ancient protective legends of turquoise or the celestial lore of zircon, tanzanite’s story is one of modern discovery and the powerful energies it is believed to possess, making it a compelling choice for those seeking meaningful and beautiful jewelry.
Geological Formation and Sources: A Singular Origin
The geological story of tanzanite is as unique as its color. It is a gemstone defined by extreme rarity, not because of its scarcity in the earth’s crust, but because of its confinement to a single, small area of the globe. This exclusivity is a primary factor in its high value and desirability.
Tanzanite is found only in one small area in Tanzania. It's not available for recreational digging, but its scarcity makes it all the more precious. The specific location is the Merelani Hills near Mount Kilimanjaro. This is the only known source of Tanzanite in the world, making it extremely rare. The gem is a variety of the mineral zoisite, and its formation is linked to a unique geological event. The Merelani Hills are part of a metamorphic belt, where intense heat and pressure transformed the original minerals into new formations. Within this belt, tanzanite was formed from the alteration of zoisite crystals, a process that introduced the elements responsible for its captivating blue-violet color.
The concentration of tanzanite in such a limited area has led to a controlled mining environment. Unlike minerals that can be found in multiple locations worldwide, such as quartz or feldspar, tanzanite’s occurrence is geologically unique. This singularity means that all tanzanite entering the market comes from this one region, giving miners and governments significant control over its supply. For gemstone enthusiasts and rockhounds, the knowledge that this gem is confined to such a specific location adds to its mystique. While one cannot simply go out and find tanzanite through recreational digging, understanding its exclusive origin deepens appreciation for the gem when it is acquired.
Gemological Properties: The Science of Blue-Violet
Tanzanite’s visual appeal is underpinned by a fascinating set of gemological properties that distinguish it from other blue gemstones like sapphire or aquamarine. Its color, clarity, and hardness make it a desirable, though delicate, choice for jewelry.
Color and Pleochroism: The most defining characteristic of tanzanite is its color. It shows a rich blue-violet hue that changes depending on the angle and lighting. This phenomenon is known as pleochroism, where a gemstone displays different colors when viewed from different crystal directions. In the case of tanzanite, the pleochroic colors are typically blue, violet, and sometimes burgundy or reddish-brown. Most tanzanite on the market has been heat-treated to enhance its blue and violet hues, removing the brownish component and stabilizing the color. This heat treatment is standard practice and is considered permanent under normal conditions, though extreme heat should be avoided.
Hardness and Durability: On the Mohs scale of hardness, tanzanite is relatively soft compared to many other gemstones. While the exact hardness is not specified in the provided sources for tanzanite itself, it is generally known in the gemological community to be around 6 to 7 on the Mohs scale. For context, the sources note that zircon ranges from 6 to 7.5 on the Mohs scale. Given that tanzanite is a variety of zoisite, its hardness is similar, making it susceptible to scratches and abrasions. This is a crucial consideration for jewelry intended for daily wear. While it is beautiful, its durability is lower than that of harder gems like blue topaz (Mohs 8) or sapphire (Mohs 9). Therefore, protective settings and mindful wearing are recommended.
Clarity and Cut: Tanzanite is typically found with good clarity, often with inclusions that are visible under magnification but not always to the naked eye. The gem’s transparency and the intensity of its color are key factors in its value. The way the stone is cut is essential to maximize its pleochroic effects. Cutters must orient the crystal to display the most desirable color combination—usually a dominant blue with violet flashes—to the viewer. The most popular cuts for tanzanite include oval, cushion, and emerald cuts, which help to showcase its depth of color.
To provide a clear comparison of the December birthstones and their key properties, the following table synthesizes data from the provided sources:
| Gemstone | Primary Color(s) | Mohs Hardness | Key Origin(s) | Notable Properties |
|---|---|---|---|---|
| Tanzanite | Blue-Violet | Not specified (typically 6-7) | Merelani Hills, Tanzania | Pleochroic (blue, violet, burgundy); heat-treated for color; extremely rare. |
| Turquoise | Sky blue, Greenish-blue | 5 – 6 | Iran, USA, Tibet, India | Semi-translucent to opaque; often contains matrix (veins); porous. |
| Zircon | Wide range, including blue | 6 – 7.5 | Sri Lanka, Australia, Myanmar, Vietnam, Cambodia | Can be heat-treated for color; can abrade; stable to chemicals but may fade in light. |
| Blue Topaz | Blue | 8 | Sri Lanka, Brazil, Mexico, Nigeria, U.S. | Most durable for everyday wear; hardest of the December stones. |
Symbolism and Metaphysical Beliefs
While tanzanite lacks the ancient, cross-cultural legends of turquoise, it has quickly developed a strong following in modern metaphysical circles. Its symbolism is closely tied to its recent discovery and its unique visual properties.
As previously mentioned, tanzanite symbolizes transformation, new beginnings, and heightened intuition. Its color, which shifts between blue and violet, is seen as a metaphor for bridging different states of consciousness or emotions. Blue is often associated with calm, communication, and truth, while violet is linked to spirituality, intuition, and imagination. The combination of these hues in a single gem makes it a powerful tool for those seeking to enhance their spiritual awareness or navigate periods of change.
For individuals born under the zodiac signs of Sagittarius (November 22 – December 21) and Capricorn (December 22 – January 19), tanzanite is believed to offer specific benefits. Associated with the planets Jupiter and Saturn and the elements of Fire and Earth respectively, tanzanite’s calming and truth-enhancing properties are thought to complement these signs. Sagittarians, known for their optimism and quest for knowledge, may find tanzanite aids in focusing their intuition, while Capricorns, pragmatic and disciplined, might use it to connect with a deeper, more spiritual side of their nature. Its spiritual meaning is often linked to protection, truth, and calmness, aligning with the broader themes of December birthstones.
Care and Cleaning: Preserving the Gem's Beauty
Given its relative softness and sensitivity to certain conditions, proper care is essential to maintain the beauty and integrity of tanzanite jewelry. Its durability is lower than that of some other birthstones, requiring specific handling and cleaning methods.
Wearing and Storage: Due to its susceptibility to scratches and abrasions, tanzanite should be protected from rough activities. It is not recommended for daily wear rings, especially for those with active lifestyles. When not being worn, tanzanite jewelry should be stored separately in a soft cloth or a lined jewelry box to prevent it from coming into contact with harder gemstones or metal surfaces that could cause damage.
Cleaning: Cleaning tanzanite is straightforward but must be done with care. The recommended method is to use a soft brush and mild soap in warm water. Gently scrub the gemstone and its setting, then rinse thoroughly with clean water and dry with a soft, lint-free cloth. It is crucial to avoid ultrasonic cleaners and steam cleaners. The vibrations from an ultrasonic cleaner can cause internal fractures in the stone to worsen, and the high heat from steam cleaning can potentially damage the gem or its setting. Always remove tanzanite jewelry before applying lotions, perfumes, or hairsprays, as chemicals can dull its surface over time.
Avoiding Heat and Light: While tanzanite is generally stable, prolonged exposure to intense heat or direct sunlight should be avoided. Although the heat treatment used to enhance its color is permanent, extreme temperatures could potentially alter the stone. Similarly, while not as light-sensitive as some other treated gems, it is wise to store it away from prolonged direct sunlight to preserve its vibrant hue.
Conclusion
Tanzanite stands as a testament to the evolving world of gemstones—a modern marvel that has swiftly claimed its place in the pantheon of traditional birthstones. Its journey from a single, remote location in Tanzania to the hands of global jewelers is a story of geological rarity and human ingenuity. As the most valuable and expensive of December’s birthstones, it offers a unique blend of intense blue-violet color, pleochroic beauty, and metaphysical symbolism centered on transformation and intuition. While its durability requires careful handling, its captivating appearance makes it a cherished gem for special occasion jewelry. For those born in December, tanzanite provides a contemporary and deeply personal alternative to the traditional turquoise and zircon, embodying the mystery and promise of the winter month it represents.