Jewellery Learning

Tanzanite – December Birthstone Meaning

THE blue-violet gem is known as “tanzanite” was literally stumbled upon by accident in the grasslands of Arusha in Tanzania. 

Tanzanite’s accidental discovery

In 1967, a Masai tribesman called Ali Juuyawatu was walking through the foothills of Mount Kilimanjaro. He spotted a purple-blue, glimmering rock in the grass and picked it up.

Ali kept the rock. Sometime later, he sold it to a local tailor called Manuel D’Souza. Manuel occasionally prospected for rubies and diamonds in the area, just as a hobby.

It wasn’t until months later, when Manuel sent the rock to an American gem laboratory to be examined, that he found out it was a completely new type of gemstone.

Tanzanite is only found near Mount Kilimanajaro in Tanzania

Tanzanite is only found near Mount Kilimanjaro in Tanzania

What is tanzanite?

Tanzanite is so rare that it is still only found in that one spot in the whole world, in a tiny area of Arusha, Tanzania. It belongs to a mineral group called zoisite. 

Since Ali Juuyawatu and Manuel D’Souza’s discovery, geologists have determined that many millions of years ago, around Mount Kilimanjaro, deposits of zoisite crystals developed underground.

These deposits existed at various depths. Sometimes they could be found right on the earth’s surface amongst the grass and the rocks. For a long time, they went undetected, until Ali Juuyawatu found one.


Gem quality tanzanite and jewellery

Once tanzanite’s discovery had been made, it didn’t remain unknown for long. It’s dazzling colour and sparkle soon bewitched both gem traders and the public.

Its rarity and exclusive source made it even more desirable.

Today, tanzanite is classed as one of the “Big Five Gems” alongside diamonds, rubies, emeralds and sapphires.

Tanzanite is blue-violet gem found only in Tanzania Africa

Gemmologist studying marquise cut tanzanite – Image credit

Why does tanzanite change colour?

Are tanzanite crystals blue or violet? The answer is both. Tanzanite is called a “pleochroic gem”.

If you hold it up to the light and turn it, you can see different colours. These can range from light blue and violet to deep indigo and burgundy.

See this beautiful effect it the video:

1.20CT Tanzanite and 0.50CT diamond ring

Tanzanite treatments

In its rough form, about 97% of tanzanite is purple-brown. It has to be heated to a high temperature to draw out the bluish-violet colour.

Only about 3% of tanzanite is naturally blue because millions of years ago it was subjected to volcanic heat under the earth’s crust.

Therefore, gemmologists and jewellers consider heating tanzanite as routine in jewellery. Unlike some other gems where heating is not desirable, experts don’t regard heat treatment to devalue tanzanite’s worth.

Tanzanite – December birthstone meaning

The West only discovered blue tanzanite in 1967. But the Masai tribes of Tanzania had long known about the purple-brown version of the mineral. They often used it as amulets.

Tanzanian mothers wear tanzanite during childbirth because the Masai believed the stone brings health and long life to newborn babies.

The tribes have also been known to use the crystals to help communication with spirits and to bring luck and strength.

Tanzanite has been used as an amulet by the Masai in Tanzania

Masai tribespeople in Tanzania – Photo by William Warby (wwarby) on

Anniversaries and celebrations

Astrologists, upon examination of the stone, decided that Tanzanite is astrologically aligned with the month of December and the star sign of Capricorn – alongside two other blue gems, turquoise and lapis lazuli.

In 2002 the American Gem Association made tanzanite the official December birthstone and the gem gift for 24th wedding anniversaries.

Rarer than diamonds

Tanzanite is rarer than diamonds because it can only be found in such a tiny, specific area of the world.

Because tanzanite tends to be found mainly as small crystals, jewellery made with dainty pieces can represent excellent value to the consumer. However, larger stones immediately rise in price.

In November 2015, an anonymous gem collector put a large assortment of gemstones on auction in Nottingham in the UK. One of the tanzanite rings alone fetched around 50,000 pounds sterling – see it pictured in the Twitter post below.

Massive tanzanite sold on auction in UK

Tanzanite sources are running out

According to a London Share Market study carried out by independent geologists, the reserves at Tanzania’s largest mining company, TanzaniteOne, will become depleted in just under 300 years.

Mining could finish even earlier. Because as the miners go deeper, extracting the gemstone becomes much harder.

Tanzanite is only known to exist in Arusha, Tanzania. It is believed that no further deposits will be found anywhere in the world. So this will mean the end of its production worldwide.

tanzanite bracelet

A 1.45CT tanzanite and 0.17CT diamond bracelet in white gold

Why tanzanite is such a special gift

For anyone who’s seen this gemstone up close, there is no denying its colour and sparkle are breathtaking. But tanzanite’s blue-violet radiance is not the only reason why it’s so desirable.

You also have to factor in the exclusivity of origin and its finite source. The idea of possessing something that not everybody else has is the main reason why we hold rare gems in high esteem.

So if you want to own a rare gem or give someone a unique gift, tanzanite is an excellent choice.

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*Any prices were quoted on 1st December 2016 and may change at any time after this date.