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  • Mineral: Zoisite      

  • Main Source of Origin: Tanzania

  • Mohs Hardness: 6.0 - 7.0

  • Birthstone: December    

Tanzanite is a variety of the mineral zoisite which is marketed after its source, Tanzania. Although zoisite has been known for a couple of centuries, Tanzanite only came under international attention in the 20th century after it was discovered in Tanzania on the African continent. It was said that in 1967, a Masai tribesman stumbled upon a cluster of intense violet-to-blue clear gemstones in the hills of Merelani in northern Tanzania. Nobody was sure what the gemstones were then and had hoped for them to be sapphires. Eventually, Tiffany & Company saw potential in the gemstone which was commercially mined in only one place and made a deal to be its main distributor; naming the gem after its country and promoted it with big publicity campaign in 1968. Almost overnight, tanzanite boomed into popularity and occasionally rivals the Big 3 precious stones for its rarity, vivid color, high clarity and potential for large cut stones.


Tanzanite can range from a clear violet-blue to a deep blue hue, sometimes burgundy when viewed at different angles. This quality to display three different colors when viewed from different directions is known as pleochroism. The low hardiness of tanzanite (6 – 7 on Mohs scale) is often considered its biggest weakness. It is an ephemeral beauty which many consider not durable enough to last for generations. Choosing a tanzanite pendant over a tanzanite ring is likely to preserve the longevity of the jewelry with considerations to its low hardiness. Along with Zircon, turquoise, and blue topaz, Tanzanite is a birthstone for December.

Other information:

  • Zodiac birthstone for Gemini, Libra, Sagittarius

  • Stone for 24th wedding anniversary

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