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Tanzanite

Poised between lush blue, vibrant violet, and rich purple, exotic tanzanite is found in only one place on earth, near majestic Mount Kilimanjaro.

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Unique Hues

Unique violet-to-blue hues

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Pure Blue

Tanzanite's rich hues rival sapphire's beauty.

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Pleochroism

Tanzanite's color blends blue hue and violet pleochroic hues.

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Tanzanian Beauty

This beautiful Merelani tanzanite crystal measures 4 x 2.9 cm.

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Pleochroic Colors

This crystal shows strong blue and brownish green pleochroic colors.

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Matrix

This crystal shows traces of the rock where it grew on its base.

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Tools

Overview

About Tanzanite

Found in just one place on earth, tanzanite is a relatively recent discovery. Tiffany & Co named this blue-violet variety of zoisite in honor of Tanzania, where it was first unearthed in 1967. Because the crystals show different colors depending on the viewing direction, cutters can fashion gems with a range of color from violetish blue to bluish violet depending on how much weight they want to retain from the rough.

Tanzanite Description Tanzanite History and Lore Tanzanite Journey

Birthstones & Anniversaries

Tanzanite is a birthstone for December, along with zircon, turquoise, and blue topaz. Tanzanite is also the gem for a 24th anniversary.

Merelani

Tanzanite has only one source: the hills of Merelani in northern Tanzania.


1967

Masai tribesman Ali Juuyawatu is credited with finding the first tanzanite crystal.


Pleochroic

Tilt tanzanite and you’ll see three distinct colors in three crystal directions.


Facts

  • Mineral: Zoisite
  • Chemistry: Ca2Al3(SiO4)3(OH)
  • Color: Violet blue to bluish violet to violet purple
  • Refractive Index: 1.691 to 1.700
  • Birefringence: 0.008 to 0.013
  • Specific Gravity: 3.35
  • Mohs Hardness: 6 to 7

Where It's Found

map

Treatments

There are a number of processes used to alter the color, apparent clarity, or improve the durability of gems.

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Synthetics

Some gemstones have synthetic counterparts that have essentially the same chemical, physical, and optical properties, but are grown by man in a laboratory.

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Imitations

Any gem can be imitated—sometimes by manmade materials or by natural materials chosen by man to impersonate a particular gem.

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gem love

Why We Love This Gemstone

1
Pleochroic

Tanzanite is pleochroic, showing three different colors when viewed from different directions.

2
One Place on Earth

Commercially mined in only one place, tanzanite is rarer than diamond.

3
Rich Blue

Tanzanite's rich blue-to-violet hues can be exceptionally beautiful.

Quality Factors

Assessment of the following characteristics determines tanzanite’s value.

Color

quality factors

Deep saturated violet blue or blue violet are the most valuable tanzanite colors. Paler hues are more commonly found.

Clarity

quality factors

Eye-visible inclusions decrease the value of tanzanite, particularly in lighter colored stones.

Cut

quality factors

Tanzanite is available in a wide range of shapes but cushion and oval cuts are most common.

Carat Weight

quality factors

Tanzanite color is less saturated in smaller sizes. Gems must be above five carats in size to have fine color.

Tanzanite Quality Factors: The Comprehensive Guide

Research

Explore sources, gemological research, and the role of gems in history.

Coated Tanzanite

Shane F. McClure and Andy H. Shen Read Article

Some Tanzanite Imitations

Lore Kiefert and Susanne Th. Schmidt , Dec 1, 1996 Read Article

Gem Wealth of Tanzania

Dona M. Dirlam, Elise B. Misiorowski, Rosemary Tozer, Karen B. Stark and Allen M. Bassett , Jun 1, 1992 Read Article

Gem-Quality Green Zoisite

N. R. Barot and Edward W. Boehm , Mar 1, 1992 Read Article