Everything you need to know about tanzanite — the rare blue gemstone found only in Tanzania. History, formation, buying guide, and where to shop.
What is Tanzanite?
Tanzanite is a rare blue-violet gemstone found only in one place on Earth — a small mining area near Mount Kilimanjaro in northern Tanzania. It is 1,000 times rarer than diamond and is one of the most sought-after colored gemstones in the world. Tanzanite was discovered in 1967 by a Maasai tribesman named Ali Juuyawatu, who noticed the unusual blue stones while herding cattle near the Merelani Hills.
Why is Tanzanite So Special?
- Found in only one location globally — the Merelani Hills near Arusha
- 1,000 times rarer than diamond
- Exhibits trichroism — shows blue, violet, and burgundy from different angles
- Named after Tanzania, the only country where it is found
- December birthstone
- Second most popular colored gemstone after sapphire
How is Tanzanite Formed?
Tanzanite formed approximately 585 million years ago in the Merelani Hills, a mountainous area at the foot of Mount Kilimanjaro. Its formation was caused by tectonic activity, heat, and pressure from the rising mountains. The gemstone is found in metamorphic rocks that were transformed by extreme geological conditions over millions of years.
The Four Grading Factors
Color
Color is the most important factor in tanzanite value. The finest tanzanite displays a deep, saturated blue with violet overtones. The color grading scale ranges from:
- AAA (Exceptional): Deep, vivid blue with violet flashes. The most valuable.
- AA (Excellent): Rich blue with violet hints. Very high quality.
- A (Very Good): Medium blue with some violet. Good value.
- Commercial: Lighter blue or brownish. Most affordable.
Clarity
Tanzanite should be eye-clean, meaning no visible inclusions to the naked eye. Unlike diamond, there is no clarity grading system for colored gemstones — it is simply "eye-clean" or not.
Carat Weight
Tanzanite is available in a wide range of sizes. Larger stones are exponentially rarer and more valuable. A 5-carat tanzanite can cost 5-10 times more per carat than a 1-carat stone of similar quality.
Cut
The cut affects the stone's brilliance and color display. Well-cut tanzanite maximizes the blue-violet color and minimizes any brownish tones.
Tanzanite Pricing Guide
- Small (0.5-1 carat): $100-400 per carat
- Medium (1-3 carats): $400-1,200 per carat
- Large (3-5 carats): $1,200-2,500 per carat
- Very Large (5+ carats): $2,500-5,000+ per carat
- Exceptional (10+ carats): $5,000-10,000+ per carat
Prices vary significantly based on color saturation. A 3-carat AAA stone can cost more than a 5-carat A stone.
How to Spot Fake Tanzanite
- Blue spinel: Imitation tanzanite. Does not show trichroism.
- Synthetic sapphire: Too perfect. Lacks natural inclusions.
- Colored glass: No brilliance or fire. Feels light.
- YAG (Yttrium Aluminum Garnet): Man-made. Too perfect.
Always request a certificate of authenticity from a reputable gemological laboratory. Real tanzanite changes color slightly when viewed from different angles due to its trichroic nature.
Where to Buy Tanzanite in Tanzania
- Arusha: Main hub for tanzanite shopping. Visit the Arusha Cultural Heritage Centre for the widest selection. Also browse shops along the main road.
- Moshi: Shops near Kilimanjaro area. Smaller selection but often better prices.
- Dar es Salaam: High-end jewelers with certified stones.
- Kilimanjaro Airport: Duty-free shops with tax-free options.
Tax-Free Shopping
Tanzania offers tax-free shopping on gemstones for tourists. Get your tax-free voucher at the shop and present it at the airport to reclaim the 18% VAT. This can save you significant money on larger purchases.
Caring for Your Tanzanite
- Store separately from other jewelry to prevent scratching
- Clean with warm soapy water and a soft brush
- Avoid ultrasonic cleaners and steam cleaners
- Avoid sudden temperature changes (thermal shock)
- Remove before heavy physical activity
