Tanzanite, December’s newest birthstone

Dec 6, 2022

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Only discovered in 1967, tanzanite is relatively new to the gemstone category. The tale goes that a Masai tribesman discovered bright blue crystals in the earth in Mererani, a small area near the base of Mount Kilimanjaro in northern Tanzania.

Having shared his find with local prospector, Manual d’Souza, mining claims were registered for the area with d’Souza believing he had found sapphire deposits. Instead, one of the world’s most rare gems was discovered – what we now know to be tanzanite, the blue variant of the mineral zoisite. 1


With an exciting new gemstone in the market, Tiffany & Co recognised its unique potential to market a new stone to rival sapphire and struck a deal to become its main distributor. Instead of calling it blue zoisite, its mineral name, they decided to name it tanzanite in homage to the location in which it was found. 1

Due to the fact the public had never heard of or seen tanzanite, in 1968 Tiffany & Co launched a publicity campaign to gain attention for this new blue rarity. 2

Tanzanite was an instant hit, not only with other designers but jewellery lovers and collectors too. The idea this gem could only be found in one place in the entire world was appealing to many, plus the stunning blue hues and high clarity certainly drew people in.

December’s birthstone

Before tanzanite, zircon and blue topaz were traditionally marketed as December’s birthstone, all of which are dazzling shades of blue. However, with the rising popularity of tanzanite, it was added as the modern birthstone for December in 2002. It’s also the gem of choice for the 24th wedding anniversary.

Tanzanite's colour

Although the mineral zoisite occurs naturally in different colours, including colourless, green, grey, pink, yellow and blue, tanzanite is the only type of zoisite which can be blue to violet-purple. 2

To be able to achieve the vivid blue, almost all sold tanzanite is enhanced by heating. The small number of gems available which haven’t been heat treated are considered incredibly rare, with the stronger blue coloured natural stones being highly valued – even more so than naturally coloured violet tanzanite. 2 As almost all tanzanite on the market is enhanced by heat, this treatment is widely accepted in the industry, it does not need to be disclosed as an enhancement.

The most valuable stones are naturally coloured medium-dark blues with custom cuts and great clarity and those larger in size. 3 Stones with a paler tone are more commonly found than those with deeper hues but can still be just as stunning. 4

Another aspect of the tanzanite’s colour is pleochroism. This means the stone can show up to three different colours when viewed at different angles. Depending on the perspective and light source, tanzanite can appear vivid blue, bright purple or even deep violet. 3

Why purchase tanzanite?

All known deposits of tanzanite are limited to just an eight kilometre strip in Mererani, northern Tanzania 7. With such a small area producing these incredible stones, many people – including some geologists – believe tanzanite mines could be depleted in as a little as 20 years. If this is the case, it would mean tanzanite is around 1,000 times rarer than diamond. 5

The Perth Mint Jewellery Boutique

You can find The Perth Mint’s jewellery store inside our landmark heritage-listed building, established by Britain’s Royal Mint in 1899 at our iconic East Perth site in Hay Street.

Our elegant jewellery boutique is home to some of the world’s most exclusive tanzanite jewellery, including tanzanite rings. Many of our high-end, hand-selected jewellery pieces are accompanied by a certificate of authenticity, as well as the peace of mind that comes with choosing to make a purchase from a Government of Western Australia-owned enterprise with a long-standing reputation for quality and integrity.

Our experts will be happy to assist you to try on precious tanzanite jewels of your choice. See how they look against your skin, ensuring your masterpiece reflects your true individuality.

Come in and explore today.


1 - https://www.americangemsociety.org/birthstones/december-birthstones/tanzanite-history/#:~:text=Tanzanite%20History,while%20tending%20livestock%20in%201967

2 - https://geology.com/gemstones/tanzanite/

3 - https://www.gemsociety.org/article/tanzanite-jewelry-and-gemstone-information/

4 - https://www.gia.edu/tanzanite

5 - https://www.tanzaniteexperience.com/10-facts-to-know-about-tanzanite/

6 - https://www.gemsociety.org/article/what-is-gemstone-pleochroism/

7 - https://www.lotusgemology.com/index.php/library/articles/144-working-the-blueseam-the-tanzanite-mines-of-merelani