Tanzanite
| Property | Details |
|---|
| Mineral | Zoisite |
| Mohs Hardness | 6 – 7 |
| Refractive Index | 1.691 – 1.700 |
| Birthstone | December (alternative) |
| Anniversary | 24th |
| Major Sources | Tanzania (the only source worldwide) |
| Treatments | Heat treatment (virtually universal, permanent) |
Overview
Tanzanite is a vivid blue-violet variety of the mineral zoisite, found in only one place on earth: the Merelani Hills of northern Tanzania, near Mount Kilimanjaro. Discovered in 1967, tanzanite quickly became one of the most popular colored gemstones due to its intense, saturated color that shifts between blue and violet depending on viewing angle and lighting.
History & Significance
Tanzanite was named by Tiffany & Co., who recognized its potential as a major new gemstone. Its single-source origin makes it approximately 1,000 times rarer than diamond by volume of deposit. Geologists estimate that the Merelani deposit is a one-time geological event, meaning once it's mined out, there will never be another source. This finite supply gives tanzanite potential as a collectible gem that may appreciate in value over time.
Color & Quality Factors
The finest tanzanite is a deep, vivid blue with violet overtones in a medium-dark tone. Stones that are too light appear washed-out, while those that are too dark lose their violet flash. Tanzanite displays pleochroism, showing different colors (blue, violet, and burgundy) from different viewing angles. Virtually all commercial tanzanite is heat-treated to develop its blue-violet color from the brownish-yellow of the natural crystals; this treatment is permanent and universally accepted. Clarity should be eye-clean—clean stones are the standard for tanzanite.
Care & Cleaning
Tanzanite ranks 6 to 7 on the Mohs scale—suitable for earrings and pendants but requires a protective setting for rings. Clean with warm soapy water only. Avoid ultrasonic cleaners, steam cleaners, sudden temperature changes, and hard impacts. Tanzanite should be treated with the same care as emerald.
Shop Tanzanite Jewelry
Browse our collection of tanzanite jewelry including rings, earrings, and pendants featuring natural tanzanite set in white gold and platinum.