What is Tanzanite: Rare Blue Gemstone Found Only in Tanzania

Tanzanite is a captivating blue-violet gemstone exclusively found near Mount Kilimanjaro in Tanzania. Discovered in 1967, it’s among the newest additions to the gemstone world yet has quickly risen to prominence due to its striking color-changing properties and extreme rarity. This comprehensive guide explores everything you need to know about tanzanite, from its geological classification to purchasing advice, helping you understand why this relatively recent discovery has become one of the most coveted colored gemstones in modern jewelry.

What is Tanzanite?

Tanzanite is a blue-violet variety of the mineral zoisite belonging to the epidote group, with its distinctive color coming from traces of vanadium within its crystal structure. Named after its only source country, Tanzania, this gemstone was commercially introduced by Tiffany & Co. in 1968, who changed its name from “blue zoisite” for marketing purposes.

• Tanzanite is the blue-violet variety of the mineral zoisite with the chemical formula Ca₂Al₃(SiO₄)(Si₂O₇)O(OH), containing traces of vanadium that create its signature color.
• It displays remarkable trichroism, meaning it can show three different colors (blue, purple, and burgundy) when viewed from different angles, a property that makes it particularly valuable and distinctive in the gemstone world.
• Over 95% of tanzanite on the market has been heat-treated to enhance its blue coloration—this is a permanent, standard industry practice that transforms the gemstone from its often brownish natural state to the prized blue-violet hues.
• Tanzanite ranks 6.5-7 on the Mohs hardness scale, making it relatively durable for everyday wear but requiring more protection than harder gemstones like diamonds or sapphires, especially considering its perfect cleavage in one direction.
• The gemstone appears different colors under various light sources—often appearing more blue under fluorescent lighting and more purple under incandescent lighting.

Understanding tanzanite’s unique properties helps explain why it commands such high value despite being a relatively recent discovery. Its color-changing nature, limited source, and pleasing blue-violet hues have established it as a distinct gemstone rather than merely an alternative to blue sapphire or other blue gems. The combination of its rarity, beautiful color, and interesting optical properties continues to make tanzanite a fascinating choice for both jewelry enthusiasts and collectors.

The History and Discovery of Tanzanite

The discovery of tanzanite in 1967 marked one of the most significant gemstone finds of the 20th century, bringing an entirely new color variety to the jewelry world. This rich blue-violet gem was found near the foothills of Mount Kilimanjaro in northern Tanzania, and its journey from discovery to international fame happened with remarkable speed.

• Manuel de Souza, a Goan tailor and prospector, discovered tanzanite in the Merelani Hills near Mount Kilimanjaro in July 1967, initially mistaking the crystals for sapphires until they were identified as a blue variety of zoisite.
• A popular origin story claims that brown zoisite crystals were transformed to blue after a lightning-caused brush fire heated the stones—while geologists debate this specific account, it accurately reflects how heat transforms the stone’s color.
• Tiffany & Co. recognized the gem’s potential immediately and launched a major marketing campaign in 1968, renaming it “tanzanite” instead of “blue zoisite” (which sounded phonetically similar to “blue suicide”) and declaring it could be found in only two places: “in Tanzania and at Tiffany’s.”
• The gemstone’s rapid market acceptance was unprecedented—within a year of its discovery, it had gone from unknown to being featured in fine jewelry around the world, establishing tanzanite as one of the most successful gemstone launches in history.
• In 2002, the American Gem Trade Association added tanzanite to the December birthstone list alongside turquoise and zircon, making it the first addition to the official birthstone list in 90 years.
• The Tanzanian government declared tanzanite a protected stone in 2017, establishing regulations requiring certification of origin for all tanzanite over one gram to combat illegal mining and preserve this national treasure.
• Scientific studies indicate the geological conditions that created tanzanite occurred only once in Earth’s history in this small location, meaning no new deposits are likely to be found elsewhere.

The history of tanzanite reflects an unusual trajectory in the gemstone world—from complete obscurity to global recognition in just a few decades. Unlike most precious gems with centuries of history and folklore, tanzanite’s story is modern, making it particularly appealing to contemporary jewelry enthusiasts looking for something with both beauty and an interesting backstory. Its limited supply and single source location continue to make it not just a beautiful gemstone but potentially an investment as well.

Tanzanite as a Birthstone

Tanzanite earned its place as one of December’s birthstones in 2002, joining the traditional turquoise and zircon. This addition by the American Gem Trade Association (AGTA) was historically significant as it marked the first change to the modern birthstone list since its establishment in 1912, recognizing tanzanite’s importance in the gemstone world despite its relatively recent discovery.

• Tanzanite was officially designated as a December birthstone by the American Gem Trade Association in 2002, making it the first addition to the birthstone list in 90 years.
• As a birthstone, tanzanite is associated with qualities such as communication, spiritual awareness, and transformative power—its deep blue-purple colors symbolize wisdom, truth, and dignity.
• December-born individuals now have three birthstone options—tanzanite, turquoise, and zircon—offering a range of blue-hued choices that represent different price points and styles.
• Unlike many traditional birthstones with centuries of myths and legends, tanzanite’s meanings are more modern and evolving, focusing on its transformative properties (reflecting how heat changes its color) and its connection to higher consciousness.
• Tanzanite is considered a “wisdom stone” in crystal healing traditions, believed to help with communication, psychic abilities, and bringing one’s true purpose into focus.
• Gift-giving of tanzanite for 24th wedding anniversaries has become increasingly popular, adding another tradition to this relatively new gemstone’s cultural significance.

As a birthstone, tanzanite offers December-born individuals a modern alternative with exceptional beauty and uniqueness. While it doesn’t carry the centuries of tradition associated with many other birthstones, its rarity and the fact that it comes from only one place on Earth make it a meaningful and distinctive choice. For those interested in a deeper exploration of birthstones throughout the year, our birthstone guide provides comprehensive information about each month’s traditional and modern options.

Where is Tanzanite Found?

Tanzanite is one of the few single-source gemstones in the world, found exclusively in a small mining area in northern Tanzania. This geographic exclusivity contributes significantly to its rarity and value, as no deposits have been discovered anywhere else on Earth despite extensive searching.

• Tanzanite is found solely in the Merelani Hills near Mount Kilimanjaro in northern Tanzania, in an area approximately 7 kilometers (4.3 miles) long and 2 kilometers (1.2 miles) wide—an incredibly small area for the world’s only source of a popular gemstone.
• The mining area is divided into blocks, with Block C controlled by TanzaniteOne (now Tanzanite One Mining Ltd.), the largest tanzanite mining company, while other blocks are mined by smaller operations and independent miners.
• Geologists believe tanzanite formed approximately 585 million years ago under unique geological conditions involving intense heat, pressure, and a specific mineral composition that occurred only in this location throughout Earth’s history.
• Mining tanzanite is labor-intensive and dangerous, with miners working in narrow shafts that can reach depths of several hundred meters in challenging conditions with temperatures exceeding 40°C (104°F).
• Scientific studies indicate that current known tanzanite reserves may be depleted within the next 20-30 years, making tanzanite not only rare but potentially finite in supply.
• The Tanzanian government has implemented strict regulations around tanzanite mining and export, including requirements for certificates of origin, to protect this national resource from smuggling and ensure local communities benefit from the trade.
• Environmental factors like groundwater, faulting of the host rocks, and complex geology make tanzanite mining technically challenging and unpredictable in terms of yield.

The extreme geographic limitation of tanzanite deposits makes this gemstone approximately 1,000 times rarer than diamonds according to some gemological estimates. This single-source nature not only contributes to tanzanite’s value but also its appeal as a truly unique gemstone that cannot be found anywhere else. For those interested in owning a piece of tanzanite, understanding its limited origin adds to the appreciation of this remarkable and finite natural treasure.

Physical Properties of Tanzanite

Tanzanite possesses several distinctive physical and optical properties that set it apart from other colored gemstones. These characteristics not only define its beauty but also influence how it should be worn and cared for as jewelry.

• Tanzanite ranks 6.5-7 on the Mohs hardness scale, making it relatively durable for a colored gemstone but significantly softer than sapphires (9) or diamonds (10), requiring more careful wear to prevent scratching.
• It has perfect cleavage in one direction, meaning it can split cleanly along that plane if struck at the wrong angle—this property requires jewelers to take special care when setting and makes tanzanite better suited for earrings and necklaces than everyday rings.
• The gemstone’s specific gravity ranges from 3.35 to 3.37, slightly heavier than many common gemstones, giving it a satisfying weight for its size.
• Tanzanite displays striking pleochroism (technically trichroism), showing different colors depending on the viewing angle: blue, purple-violet, and burgundy-red, with the blue axis being most prized.
• Most tanzanite on the market has been heat-treated at approximately 600°C (1112°F) to permanently transform its typical brownish color to the prized blue-violet hues—this treatment is standard industry practice and does not decrease the gem’s value.
• Its refractive index of 1.691-1.700 gives tanzanite good brilliance, though not as great as diamonds (2.42) or sapphires (1.77).
• Tanzanite can display a distinctive purplish fluorescence under ultraviolet light, which gemologists can use as one identifying characteristic.

These physical properties make tanzanite not only beautiful but scientifically fascinating. Its ability to appear dramatically different colors depending on lighting conditions and viewing angle creates a dynamic, changing appearance that many jewelry lovers appreciate. However, these same properties mean tanzanite requires more careful handling than some harder gemstones, making it important to understand its physical characteristics before purchasing or wearing tanzanite jewelry.

Tanzanite Colors and Value

Tanzanite’s value is largely determined by its color, with the most prized specimens displaying rich blue to violet-blue hues. The market preferences and factors affecting tanzanite’s color make this one of the most important aspects to understand when purchasing this gemstone.

• The most valuable tanzanite displays a strong, saturated blue to violet-blue color, often described as “blurple”—stones with primarily purple or burgundy hues generally command lower prices.
• Color saturation dramatically affects value—richly colored tanzanite can sell for many times the price of paler stones of the same size and clarity, with top-quality blue material fetching premium prices.
• Larger tanzanites typically show stronger color than smaller stones due to the longer path length for light travel, making larger stones disproportionately more valuable per carat.
• Stones over 5 carats with exceptional color are particularly rare and valuable, with museum-quality specimens above 20 carats commanding prices comparable to fine sapphires.
• Most tanzanite is heated to permanently enhance its blue color, a standard industry practice—the rare unheated stones with naturally strong blue color can command a premium of up to 30% among collectors.
• When examining tanzanite in person, it’s worth viewing it under different light sources, as it appears more blue under fluorescent light and more purple under incandescent lighting.
• Color zoning (uneven color distribution) can significantly reduce a tanzanite’s value, with evenly colored stones being most desirable.

Tanzanite’s color is truly its most important quality factor. Unlike diamonds where cut, clarity, and color all heavily influence price, with tanzanite, a medium-quality stone with exceptional color may be worth significantly more than a flawless, perfectly cut stone with weak color. This makes understanding color grading particularly important when shopping for tanzanite. For the best value, many experts recommend prioritizing rich, evenly distributed color over absolute clarity or perfect cutting.

Tanzanite vs. Similar Gemstones

Tanzanite is sometimes compared to other blue gemstones, particularly blue sapphire and iolite. Understanding how tanzanite differs from these similar-looking stones helps buyers make informed decisions and appreciate tanzanite’s unique characteristics.

• Tanzanite is often compared to blue sapphire, but tanzanite’s distinctive violet-blue color usually contains more purple undertones than the pure blue typically found in fine sapphires.
• When compared to sapphire, tanzanite is significantly less expensive (generally 1/2 to 1/3 the price of comparable blue sapphire), offers pleochroism (color-changing properties), but is less durable (6.5-7 versus sapphire’s 9 on the Mohs scale).
• Iolite is most frequently confused with tanzanite due to similar color and pleochroic properties, but iolite typically displays more grayish-blue hues, is harder (7-7.5 on Mohs scale), and costs significantly less.
• Blue topaz can resemble lighter tanzanite but lacks the purple undertones, has a different crystal structure, and typically sells for a fraction of tanzanite’s price.
• Lab-created tanzanite does not exist commercially—stones marketed as “synthetic tanzanite” are typically cubic zirconia or created sapphire with similar coloring but different physical and optical properties.
• Cubic zirconia and glass imitations can be distinguished from tanzanite by their lack of pleochroism, different optical properties, and usually perfect clarity.
• Tanzanite’s unique pleochroism (showing blue, purple, and burgundy from different angles) is its most distinctive identifying feature and is not perfectly replicated in any similar gemstone.

Understanding these differences helps consumers make informed choices when purchasing blue gemstones. While tanzanite commands premium prices compared to many blue stones, it remains more affordable than fine blue sapphire while offering unique color properties. For those seeking blue gemstones on a budget, alternatives like blue topaz or iolite provide options, but none offer the exact same color-changing properties and violet-blue hue that have made tanzanite so desirable.

Caring for Tanzanite Jewelry

Tanzanite’s 6.5-7 hardness on the Mohs scale and perfect cleavage in one direction mean it requires more careful handling than harder gemstones. Proper care will ensure your tanzanite jewelry remains beautiful for generations.

• Avoid exposing tanzanite to sudden temperature changes or extreme heat, as thermal shock can cause the stone to fracture along its cleavage planes—never steam clean or use ultrasonic cleaners on tanzanite jewelry.
• Clean tanzanite gently using warm water, mild soap, and a soft brush, avoiding harsh chemicals, particularly acids and alkaline solutions that can damage both the stone and its setting.
• Store tanzanite jewelry separately in a fabric-lined box or soft pouch to prevent scratches from harder gemstones and contact with other jewelry pieces that might cause damage.
• Remove tanzanite rings before activities involving impact or hand exposure to rough surfaces—tanzanite is better suited for earrings, pendants, and occasional-wear rings rather than everyday rings exposed to bumps and knocks.
• Avoid wearing tanzanite during sports, household cleaning, gardening, or other activities that risk impact or exposure to chemicals.
• Have tanzanite jewelry, especially rings, checked annually by a jeweler to ensure settings remain secure, as loose prongs or settings can lead to loss or damage.
• Though tanzanite is stable in normal light, extremely long exposure to intense sunlight may gradually fade its color over many years, so avoid prolonged direct sunlight exposure.

With proper care, tanzanite jewelry can remain beautiful for generations. While it’s not as indestructible as diamonds, tanzanite is durable enough for regular wear when appropriate precautions are taken. Understanding tanzanite’s physical properties helps owners make informed decisions about when and how to wear their tanzanite pieces, ensuring these beautiful gemstones remain family treasures for years to come.

Buying Guide for Tanzanite

Purchasing tanzanite requires understanding various quality factors and market considerations to ensure you get the best value. This guide outlines the key aspects to consider when shopping for tanzanite jewelry.

• Color is the most important factor in valuing tanzanite—look for rich, saturated blue to violet-blue hues with minimal gray or brown undertones, as these command the highest prices and show the stone’s beauty best.
• Size significantly impacts price—tanzanite exhibits a steep price curve, with stones over 5 carats commanding much higher per-carat prices than smaller stones because larger specimens with fine color are exceptionally rare.
• Clarity affects value but is secondary to color—eye-clean stones (no visible inclusions to the naked eye) are preferred, though minor inclusions are acceptable if they don’t affect the stone’s brilliance or durability.
• Cut quality influences how well the stone displays its color and brilliance—well-cut tanzanite should show evenly distributed color and good brilliance with proper proportions for the specific shape.
• Shape preferences vary, with cushion, oval, and round cuts being traditional favorites for tanzanite, though emerald cuts and other fancy shapes can beautifully display the stone’s pleochroism when properly oriented.
• Certification from reputable gemological laboratories like GIA, AGL, or SSEF provides assurance of a stone’s authenticity and quality—particularly important for larger or more expensive stones.
• Ethical sourcing concerns have led to programs like the Tanzanite Foundation’s Mark of Rarity that certify stones as being ethically and legally mined and traded.

When shopping for tanzanite, prioritize color over absolute clarity or perfect cutting if working with a limited budget. Since heat treatment is standard industry practice for tanzanite, there’s no need to pay a premium for treated stones, though naturally blue tanzanite (rare and usually certified as such) may command higher prices among collectors. Always purchase from reputable dealers who can provide proper documentation, especially for larger stones. With proper knowledge, you can select a beautiful tanzanite that represents good value while avoiding common pitfalls in the colored gemstone market.

Tanzanite Myths and Facts

Tanzanite’s relatively brief history in the gemstone world has led to some misconceptions alongside factual information. Clarifying these points helps collectors and jewelry enthusiasts better understand this unique gemstone’s true nature and value.

• Tanzanite’s single-source origin in Tanzania is a geological reality confirmed by extensive exploration—unlike some gemstones where marketing exaggerates rarity, tanzanite’s exclusivity to one small area near Mount Kilimanjaro is scientifically documented.
• Geological studies indicate tanzanite supplies are finite, with known deposits potentially depleted within 20-30 years—this limited supply situation is not marketing hype but based on scientific assessment of the mining area.
• Heat treatment is standard practice for tanzanite, permanently enhancing its blue color—this process is accepted by the jewelry industry without value penalty and affects over 95% of tanzanite on the market.
• While tanzanite requires more care than diamonds or sapphires due to its 6.5-7 hardness and perfect cleavage, properly set stones are durable enough for most jewelry applications, particularly earrings, pendants, and occasional-wear rings.
• The color-changing effect in tanzanite results from genuine trichroism—a physical property where the crystal structure displays different colors (blue, purple, and burgundy) when viewed from different angles under different lighting conditions.
• True synthetic tanzanite does not exist commercially—stones marketed as “lab-created tanzanite” are actually simulants like colored cubic zirconia or created sapphire that mimic tanzanite’s appearance but lack its optical and physical properties.
• The American Gem Trade Association officially added tanzanite to the December birthstone list in 2002, making it the first addition to the modern birthstone list since its establishment in 1912.

Understanding these key points helps consumers make informed decisions when purchasing tanzanite. Despite being a newcomer in geological terms, tanzanite has established itself as a legitimate precious gemstone with unique properties and genuine rarity. Its single-source nature and potentially finite supply make it not just a beautiful addition to a jewelry collection but possibly a sound investment as well. By understanding what makes tanzanite truly special, consumers can better appreciate its distinctive place in the world of colored gemstones.

Conclusion

Tanzanite stands as one of the gemstone world’s most remarkable discoveries – a stunning blue-violet stone with color-changing properties that was unknown until 1967. From its exclusive mines in Tanzania to its addition as an official birthstone in 2002, tanzanite has quickly established itself in the jewelry world due to its unique properties, breathtaking color, and genuine rarity.

For those considering tanzanite jewelry, understanding its distinctive qualities helps in both appreciation and proper care. While requiring more careful handling than some harder gemstones, tanzanite’s extraordinary color, pleochroism, and limited availability make it a worthy addition to any jewelry collection. As tanzanite supplies are projected to diminish in coming decades, these captivating gemstones may become even more precious, combining beauty with genuine exclusivity in a way few other gemstones can match.