Tanzanite

Tanzanite is a beautiful blue and purple stone. It only comes from one place on Earth. This place is in a land called Tanzania.

The stone can look like many colors. It can look blue, violet, or even red. This happens when the light hits it from different sides.

When first found, the stones look brown. People use heat to change them. The heat removes the brown color. This makes the blue and purple colors shine.

Many people use these stones for jewelry. It is a special stone for those born in December.

Tanzanite is a rare blue and violet gemstone. It is a type of mineral called zoisite. Small amounts of vanadium make it change color. This stone is only found in one small area. It comes from the Mererani Hills in Tanzania.

Tanzanite has a special trait called trichroism. This means it shows different colors from different sides. It can look blue, violet, or burgundy. The colors also change under different lights. Fluorescent light makes the blue look bright. Incandescent light makes the violet colors stand out.

When first mined, the stones look reddish brown. To fix this, people use heat treatment. They heat the stones in a furnace. This removes the brown color. It leaves behind a strong blue or violet color. This process is called making the stone dichroic.

No one has made tanzanite in a lab. All real tanzanite comes from the Earth. People sometimes use glass or other gems to copy it. In 2002, it became the birthstone for December.

Tanzanite is a rare and beautiful gemstone. It is a blue and violet variety of a mineral called zoisite. This stone is special because it is found in only one place on Earth. You can only find it in the Simanjiro District of Tanzania. It comes from a tiny mining area near the Mererani Hills. This stone is very important to collectors and jewelers everywhere.

Tanzanite has a very interesting way of showing color. It has a trait called trichroism. This means the stone shows different colors depending on how you look at it. It can appear blue, violet, or even burgundy. The light also changes how we see the colors. Fluorescent light makes the blue parts look much brighter. Incandescent light helps the violet colors stand out.

This happens because of how light moves through the crystal.

The history of this gem began a long time ago. Tanzanite formed about 585 million years ago. It was made by huge movements in the Earth's plates. This created intense heat near what is now Mount Kilimanjaro. In January 1967, Jumanne Mhero Ngoma found the sparkling stones. He was working near the Mererani hills. He later received a certificate and a reward from the President of Tanzania.

Many people helped identify this new treasure. A tailor named Manuel de Souza also found fragments in July 1967. He thought the stones were a different mineral at first. Later, experts at Harvard and the British Museum confirmed it was zoisite. Tiffany & Co. gave it the name "tanzanite" in 1968. They wanted a name that sounded better for customers. In 2002, it became the official December birthstone. This was the first change to that list since 1912.

Working with tanzanite requires a special step to make it pretty. In its rough state, the stone looks reddish brown. To fix this, people use heat treatment. They put the stones in a furnace at high temperatures. This removes the brown color and leaves blue and violet. After heating, the stone is called dichroic.

You cannot make real tanzanite in a laboratory. Every real piece comes from the ground in Tanzania.

Tanzanite is a rare and striking gemstone. It is the blue and violet variety of a mineral called zoisite. Chemically, zoisite is a calcium aluminium hydroxyl sorosilicate. The beautiful colors we see in tanzanite are caused by small amounts of vanadium within the crystal. This gemstone is highly significant because it is found in only one place on Earth. It is located in the Simanjiro District of the Manyara Region in Tanzania. Specifically, it comes from a very small mining area near the Mererani Hills.

The visual properties of tanzanite are quite complex. The mineral is known for remarkably strong trichroism. Trichroism means the crystal shows different colors depending on its orientation. As you turn the stone, it can appear blue, violet, or even burgundy. The type of light used also changes the appearance. Fluorescent light makes the blue hues more evident. In contrast, incandescent illumination makes the violet colors easier to see.

To reach its final beauty, tanzanite often undergoes a specific process. In its rough state, the mineral is often reddish brown or clear. To remove this brownish "veil," the stones must undergo heat treatment. This is done by heating the stones in a furnace, usually at temperatures between 450 and 600 degrees Celsius for 30 minutes. This process changes the stone from being trichroic to being dichroic. As a dichroic stone, it reflects a range of colors from violet through bluish-violet to indigo and blue. While most stones require this, some stones from the "D block" area were found naturally blue due to ancient wildfires.

The history of tanzanite began 585 million years ago during the mid-Ediacaran Period. It formed through massive plate tectonic activity and intense heat near Mount Kilimanjaro. The modern discovery happened in 1967. In January of that year, Jumanne Mhero Ngoma found sparkling blue stones at the Mererani hills. Later that July, a tailor named Manuel de Souza also found blue fragments. He initially mistook them for olivine or dumortierite. Eventually, experts from Harvard University and the British Museum confirmed the mineral was zoisite. Tiffany & Co. gave the stone the name "tanzanite" in 1968. They chose this name because "blue zoisite" was not considered consumer friendly.

Tanzanite has a unique commercial history in Tanzania. From 1967, about two million carats were mined before the government nationalized the mines in 1971. In 1990, the government divided the mines into four sections: Blocks A, B, C, and D. Blocks A and C went to large operators, while B and D were for local miners. In 2005, a lease for Block C was renewed for US$40 million. In 2010, the government banned the export of rough stones weighing more than one gram. This was done to encourage local processing and boost the economy. In 2020, a single miner named Saniniu Laizer found two stones weighing 11.14 kg. He sold them for TSh 7.74 billion, which is about US $3.35 million.

Collectors look for specific qualities when grading tanzanite. There is no single universal grading method. However, the Tanzanite Foundation uses a scale including bluish-violet, indigo, and violetish-blue. As of mid-March 2026, values can range from $100 to $800 per carat. Clarity is also very important. The Gemological Institute of America calls tanzanite a Type I gemstone. This means it is usually "eye-clean," or free of inclusions visible to the unaided eye. If a stone has inclusions that can be seen easily, its value drops significantly.

It is important to distinguish real tanzanite from imitations. Tanzanite cannot be successfully synthesized in a laboratory, so all genuine stones are natural. Some people use cubic zirconia or colored glass to imitate it. Others use synthetic forsterite, which looks similar but can be identified using a refractometer. A refractometer measures how light bends; forsterite has an index of 1.63–1.67, while tanzanite is higher at 1.685–1.707. Some lower-grade stones are also treated with a cobalt coating to make them look darker. Because these coatings can rub off, they must be disclosed at the point of sale.