Tanzanite

Introduction

Tanzanite is a captivating gemstone with a remarkable story and unique attributes that set it apart in the world of precious stones. Discovered in 1967 in the Merelani Hills at the base of Mount Kilimanjaro in Tanzania, this gemstone was named by Tiffany & Co. after its country of origin. Tanzanite's appeal lies not only in its vibrant blue and violet hues, which can appear to change color depending on the viewing angle and lighting, but also in its rarity, as it is found in only one place on Earth. The gemstone has rapidly gained popularity due to its striking beauty and its associations with luxury and exclusivity.

Color and Varieties

Tanzanite's color spectrum is one of its most captivating features. The gemstone can exhibit a range of hues from deep, velvety blue to a vibrant violet, depending on the crystal orientation and lighting. This strong pleochroism means that different angles can reveal different colors, adding to Tanzanite's mystique and appeal. While most Tanzanite on the market has been heat-treated to remove a brownish hue and bring out its vivid blue and violet tones, some rare stones display these desirable colors naturally. Additionally, the intensity of Tanzanite's color can vary from light lavender to an intense royal blue, with the deepest colors typically being the most valued.

Formation and Occurrence

Tanzanite forms in a unique geological environment that involves specific conditions of high temperature and pressure within metamorphic rocks. This gemstone is found exclusively in a small mining area in Tanzania, making it approximately 1,000 times rarer than diamonds. The gem-bearing rocks in the region formed over 585 million years ago during a process called plate tectonics, where intense geological activity created the conditions necessary for Tanzanite’s formation. This geographical restriction, combined with the depth at which Tanzanite is found and the complexities of mining, contributes to the gemstone's rarity and value.

Historical and Cultural Significance

Since its discovery, Tanzanite has captured the imagination of jewelers, gem enthusiasts, and the general public alike. Tiffany & Co. played a significant role in popularizing the stone by branding it with an exotic allure and promoting it as the 'gemstone of the 20th century.' In Maasai culture, Tanzanite is believed to be a stone of transformation, representing new beginnings, and it is often given to newborns to bring them a prosperous life. The gemstone has also found its place as a December birthstone, often symbolizing truth, dignity, and spiritual clarity. Its status as a gem that is "a thousand times rarer than diamonds" further enhances its allure as a luxury item.

Identification and Grading

Identifying Tanzanite involves examining its unique optical properties, such as its trichroic nature, which allows it to exhibit different colors when viewed from different angles. The grading of Tanzanite is primarily based on color, clarity, cut, and carat weight. The most desirable Tanzanites exhibit a deep, rich blue or violet color with minimal inclusions, although some collectors appreciate stones with visible inclusions that add character to the gemstone. Cut quality is essential in maximizing Tanzanite's color and brilliance, as a well-cut stone will display its pleochroic properties to the best effect. Carat weight can also significantly impact value, with larger stones being particularly rare and sought after.

Treatments and Enhancements

Most Tanzanite on the market has undergone heat treatment, which is a common and accepted practice to enhance the stone's natural colors. This process involves heating the gemstone to around 500-600 degrees Celsius to remove any brownish overtones and enhance the blue and violet hues. This treatment is considered stable, permanent, and does not detract from the gemstone’s value. In fact, untreated Tanzanite is quite rare and typically exhibits a brownish coloration that is less desirable in the market. Heat-treated Tanzanite is almost universally preferred for its striking color and brilliance.

Cutting and Polishing

The cutting and polishing of Tanzanite require a high level of skill and precision, particularly due to its pleochroic nature. Expert gem cutters must carefully orient the gemstone to maximize its desirable colors and minimize any potential color zoning. Tanzanite is typically cut into a variety of shapes, including rounds, ovals, cushions, and emerald cuts, with each shape chosen to best display the stone’s vivid colors and internal characteristics. Due to its relative softness compared to other gemstones, Tanzanite is often cut with protective settings when used in rings and other jewelry pieces that may be subject to daily wear.

Uses

Tanzanite is primarily used in fine jewelry and is highly prized for its unique color and rarity. It is commonly set in rings, earrings, necklaces, and bracelets, often accented with diamonds to enhance its natural beauty. Due to its relatively soft nature, Tanzanite is usually recommended for pieces that are less likely to be exposed to rough wear, such as pendants and earrings. However, with proper care, Tanzanite rings and bracelets can also be worn regularly. The gemstone’s vibrant hues and rarity make it a popular choice for bespoke and high-end jewelry designs.

Famous Specimens

Several famous Tanzanite specimens have made headlines over the years, including some extraordinary finds that have been cut into stunning jewelry pieces. The "Queen of Kilimanjaro" is one of the largest faceted Tanzanite gemstones in the world, weighing 242 carats and set in a tiara with 803 diamonds and 913 green garnets. Other notable examples include Tanzanite pieces worn by celebrities on the red carpet, which have helped elevate the gemstone's profile among collectors and the general public. These specimens often serve as centerpieces in exclusive collections and exhibitions, showcasing the exceptional beauty and rarity of Tanzanite.

Market and Value

The value of Tanzanite has been steadily rising since its discovery due to its limited supply and increasing demand. Factors influencing its value include color intensity, clarity, size, and cut quality. Deep blue Tanzanite stones with high clarity are considered the most valuable, especially when they are over several carats in weight. The market is also influenced by the fact that Tanzanite is mined from a single source, leading to concerns about its long-term availability. As a result, Tanzanite is often seen as a good investment, with prices expected to continue to rise as the mines deplete over time.

Care and Maintenance

Due to its relative softness and brittleness, Tanzanite requires careful handling to maintain its beauty. It should be cleaned using warm, soapy water and a soft brush, avoiding ultrasonic cleaners and harsh chemicals that can damage the stone. Tanzanite should also be stored away from harder gemstones to prevent scratches and should be protected from sharp blows. Exposure to high heat and sudden temperature changes should be avoided, as they can cause cracks or fractures in the stone. With proper care, Tanzanite jewelry can be enjoyed for many years, maintaining its vibrant color and brilliance.

Synthetic and Imitation

While synthetic Tanzanite has not been successfully produced to date, there are various imitations on the market, including colored glass and synthetic forsterite, which can resemble Tanzanite's blue-violet color. These imitations can sometimes be mistaken for genuine Tanzanite, especially by the untrained eye. Therefore, it is essential for buyers to purchase Tanzanite from reputable dealers and to request certification or a professional appraisal when purchasing higher-value stones. Gemological testing, including refractive index and pleochroism analysis, can help distinguish genuine Tanzanite from its imitations.

Environmental and Ethical Concerns

The mining of Tanzanite has raised several environmental and ethical issues. The mining process can lead to habitat destruction and soil erosion, and there have been concerns about the working conditions in Tanzanian mines, including child labor and inadequate safety measures. In recent years, there has been a push towards more ethical and sustainable mining practices, with some mines seeking certification for ethical sourcing. Consumers are increasingly encouraged to purchase Tanzanite that has been ethically sourced to support better practices in the gemstone industry and to ensure that their purchases do not contribute to environmental degradation or human rights abuses.