Tanzanite, the captivating December birthstone, is a relatively recent addition to the world of gemstones, yet its allure and rarity have quickly established it as a cherished gem among collectors and jewelry enthusiasts. Discovered in the Merelani Hills of Tanzania in the mid-20th century, tanzanite is celebrated for its vivid, velvety blue to violet hues, its high clarity, and its unique geological origins. As a December birthstone, it is associated with themes of friendship and is also the gemstone of the 24th wedding anniversary. This article delves into the history, gemological properties, and cultural significance of tanzanite, offering a comprehensive overview of this extraordinary stone.
History and Lore
Tanzanite was first identified in 1962, when blue stones emerging from Tanzania were recognized as the mineral zoisite. However, it was not until 1967 that the primary source of this gemstone was located in the Merelani Hills, marking the beginning of its commercial mining. The stone was named "tanzanite" in honor of Tanzania, the only country where it is found. This naming convention reflects the deep connection between the gemstone and its place of origin, emphasizing the exclusivity and national pride associated with its discovery.
The promotion of tanzanite as a gemstone was significantly advanced by the renowned jewelry house Tiffany & Co. Recognizing the potential of tanzanite, Tiffany launched a major advertising campaign in 1968 to introduce the gem to the international market. This campaign highlighted the stone's striking color and clarity, contributing to its rapid rise in popularity. Today, tanzanite is not only a December birthstone but also a symbol of the 24th wedding anniversary, further cementing its place in both modern and traditional gemstone lore.
The cultural significance of tanzanite is further enhanced by its rarity. Found exclusively in the Merelani Hills, tanzanite's limited geographic distribution adds to its mystique and value. The mining operations in this region are extensive, with mines dug over 100 meters deep into the earth. These conditions contribute to the stone's scarcity, making each tanzanite gem a unique and precious treasure.
Geological Formation and Sources
Tanzanite is a variety of the mineral zoisite, chemically classified as calcium aluminum silicate with the formula Ca₂Al₃(SiO₄)₃(OH). Its distinctive blue to violet coloration is due to the presence of trace amounts of vanadium, which causes a phenomenon known as pleochroism. This means that tanzanite can display different colors when viewed from different angles, typically showing shades of blue, violet, and brown. However, through heat treatment, the brown and yellow tones are often removed, enhancing the blue and violet hues that are most desirable in the gem trade.
The primary source of tanzanite is the Merelani Hills in northern Tanzania, a region characterized by grass-covered hillsides, scrub brush, and rocky soil. The mining operations in this area are both mechanized and labor-intensive, involving thousands of workers who extract the gemstones from depths exceeding 100 meters. The landscape surrounding the mines is marked by the snow-capped slopes of Mount Kilimanjaro, adding a dramatic backdrop to the mining activity.
The geological conditions that produce tanzanite are unique to the Merelani Hills. The formation of zoisite into tanzanite involves a combination of high pressure and specific chemical conditions that are not found in other parts of the world. This exclusivity ensures that tanzanite remains one of the most rare and sought-after gemstones, with its value expected to increase as the supply diminishes over time.
Gemological Properties
Tanzanite is distinguished by several key gemological properties that contribute to its desirability and value. These properties include its color, clarity, hardness, and refractive index, all of which are essential considerations for gemologists and jewelers.
Color
The most striking feature of tanzanite is its color, which ranges from a deep, rich blue to a vibrant violet. The blue tones are generally considered more valuable, as they are rarer and more intensely saturated. The pleochroism of tanzanite allows it to display multiple colors, which can be enhanced through careful cutting and polishing. The color of tanzanite is often improved through heat treatment, a process that removes undesirable brown and yellow hues, resulting in a more uniform and desirable blue or violet color.
Clarity
Tanzanite is typically found with good clarity, although it may contain minor inclusions that are characteristic of natural gemstones. These inclusions are often visible under magnification and can affect the stone's transparency and brilliance. High-quality tanzanite is characterized by excellent clarity, with minimal inclusions that do not detract from its overall appearance. The clarity of tanzanite is an important factor in determining its value, with stones that exhibit high clarity commanding higher prices in the market.
Hardness
On the Mohs scale of mineral hardness, tanzanite is rated at 6 to 7. This places it in the medium-hardness category, making it suitable for use in jewelry but requiring careful handling to avoid scratches and other damage. The hardness of tanzanite is an important consideration for jewelers, as it influences the choice of settings and the type of wear for which the gemstone is appropriate. Tanzanite is generally recommended for use in earrings, pendants, and other jewelry that is less likely to be subjected to frequent impact or abrasion.
Refractive Index
The refractive index of tanzanite ranges from 1.694 to 1.703, which is relatively high for a gemstone of its hardness. This refractive index contributes to the stone's brilliance and fire, making it an attractive choice for jewelry. The refractive properties of tanzanite are further enhanced by its pleochroism, which allows the gemstone to display different colors when viewed from different angles. This optical phenomenon adds to the visual appeal of tanzanite and is a key factor in its desirability as a gemstone.
Symbolism and Metaphysical Beliefs
Tanzanite is not only valued for its aesthetic qualities but also for its symbolic and metaphysical associations. As the December birthstone, it is associated with the theme of friendship, representing the bonds that connect individuals and the importance of nurturing these relationships. Additionally, tanzanite is believed to have several metaphysical properties that contribute to its appeal among those who practice gemstone therapy or spiritual healing.
Emotional and Psychological Benefits
Tanzanite is often associated with emotional healing and spiritual growth. It is believed to help individuals process and release negative emotions, promoting a sense of calm and inner peace. The stone is also thought to enhance intuition and spiritual awareness, making it a popular choice for those engaged in meditation or other spiritual practices. These properties make tanzanite a valuable tool for those seeking emotional balance and personal growth.
Physical and Health Benefits
While the physical health benefits of tanzanite are not scientifically proven, some believe that the gemstone can aid in the treatment of various ailments. It is thought to support the immune system and promote overall well-being. Additionally, tanzanite is believed to have a calming effect on the body, helping to reduce stress and anxiety. These perceived benefits contribute to the stone's popularity among those who use gemstones for holistic health purposes.
Cultural and Historical Significance
The cultural and historical significance of tanzanite is closely tied to its discovery and promotion in the mid-20th century. As a relatively new gemstone, tanzanite has a unique place in the history of gemology, representing the intersection of geological rarity and modern marketing. Its association with Tiffany & Co. and the international advertising campaign launched in 1968 has cemented its status as a symbol of luxury and exclusivity. Furthermore, its designation as the gemstone for the 24th wedding anniversary adds to its cultural significance, making it a meaningful choice for those celebrating long-term partnerships.
Care and Cleaning
Given its medium hardness and pleochroism, tanzanite requires careful handling and appropriate cleaning methods to maintain its beauty and longevity. The following guidelines provide practical advice for the care and maintenance of tanzanite jewelry:
Cleaning
Tanzanite can be cleaned using mild soapy water and a soft cloth or a soft-bristled brush. It is important to avoid using harsh chemicals or ultrasonic cleaners, as these can damage the gemstone's surface and potentially remove any treatments that have been applied to enhance its color. A gentle wipe with a damp cloth is usually sufficient to remove dirt and debris from the stone.
Storage
To prevent scratches and other damage, tanzanite jewelry should be stored separately from other gemstones, particularly those that are harder on the Mohs scale. Storing the gemstone in a soft pouch or a lined jewelry box can help protect it from abrasion and other forms of wear. It is also advisable to avoid exposing tanzanite to direct sunlight for extended periods, as this can cause fading or other changes in the stone's appearance.
Wearing
Tanzanite is best suited for jewelry that is worn occasionally rather than daily. Rings and other items that are more likely to experience impact or abrasion should be avoided, as they can increase the risk of chipping or scratching the gemstone. Earrings, pendants, and other delicate pieces are generally more appropriate for tanzanite, as they are less likely to be subjected to the wear and tear associated with everyday use.
Professional Maintenance
For more thorough cleaning and maintenance, it is advisable to consult a professional jeweler. Jewelers can provide specialized services such as re-polishing and re-setting, which can help restore the gemstone's brilliance and ensure its continued beauty. Regular inspections by a professional can also help identify any potential issues, such as loose settings or other damage, that may require attention.
Conclusion
Tanzanite, the December birthstone, is a remarkable gemstone that combines rarity, beauty, and cultural significance. Discovered in the Merelani Hills of Tanzania, tanzanite is celebrated for its vibrant blue to violet hues and its unique geological origins. The promotion of tanzanite by Tiffany & Co. in the 1960s played a crucial role in establishing its place in the world of gemstones, and its association with the 24th wedding anniversary further enhances its symbolic importance.
From a gemological perspective, tanzanite is distinguished by its color, clarity, hardness, and refractive index, all of which contribute to its desirability and value. The stone's pleochroism, which allows it to display different colors when viewed from different angles, is a key factor in its visual appeal. However, this property also requires careful cutting and polishing to ensure that the most desirable colors are enhanced and displayed.
In addition to its aesthetic qualities, tanzanite is associated with several metaphysical and symbolic properties. It is believed to promote emotional healing, spiritual growth, and overall well-being, making it a popular choice among those who practice gemstone therapy. Its designation as the December birthstone and its association with friendship further add to its cultural significance.
To maintain the beauty and longevity of tanzanite jewelry, it is important to follow appropriate care and cleaning methods. Gentle cleaning with mild soapy water, proper storage, and mindful wearing practices can help preserve the gemstone's appearance. Consulting a professional jeweler for more thorough maintenance is also advisable, ensuring that the gemstone remains a cherished and enduring symbol of its significance.
Tanzanite's unique combination of rarity, beauty, and cultural significance ensures its continued popularity among gemstone enthusiasts, jewelry buyers, and students of gemology. As a December birthstone, it represents not only the month of its association but also the enduring value of friendship and the importance of nurturing meaningful connections.