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December’s birthstone Tanzanite

Updated: Apr 18, 2023

Tiffany and Co. called it “the loveliest blue gemstone discovered in over 2000 years”, so here’s hoping you find some jewellery featuring December’s birthstone Tanzanite under the tree this Christmas.

December's birthstone Tanzanite

December’s birthstone Tanzanite

Though Tanzanite is simply a blue form of the gemstone zoisite, ‘blue zoisite’ was thought rather a dull name for such a sparkling beauty. Tiffany & Co, who owned the mines, needed a name more likely to catch the imagination of the consumer, and so Tanzanite was born – named after Tanzania, the African country that holds the world’s only known source of gem-quality Tanzanite.

Discovered by a Masai tribesman in 1967, Tanzanite is a very young gem in commercial terms. Nevertheless, it has achieved spectacular success and is now the most popular blue stone after sapphire.

Tanzanite occurs in various shades of blue ranging from the deep violet blue to a much lighter hue. The bluer, richer end of this spectrum is the most valuable. Most Tanzanite on the market has been heat treated to achieve this strong colour and a naturally deep blue stone will be very expensive.

Its mesmerising colour is not the only thing that makes December’s birthstone special. It is what gemmologists call a ‘phenomenal’ gemstone – a gemstone with interesting optical properties. Tanzanite is pleochroic, which means its crystal structure displays different colours depending on the angle from which it is viewed. A skilled gem cutter can cut a Tanzanite to take advantage of this.

At 6.5 on the Mohs scale of hardness, Tanzanite is not a stone for everyday rings and bracelets but is more suited to occasion wear or earrings and necklaces that won’t be subject to knocks and scratches. You should always store each of your gemstone jewellery pieces in its own box or compartment, but this is particularly important for relatively soft gemstones like Tanzanite, which is easily scratched by many harder popular gemstones.

Tanzanite was discovered too recently to have acquired the mythology and lore that other gemstones have, but advocates of crystal therapy say that Tanzanite is a stone of spiritual growth and promotes psychic power.

Photo credit and thanks to: Featured is a stunning tanzanite cut by Jeff Hapeman for SITR. Acquired from purple gemstone hoarder, Don Johnson. This gem now resides in a custom ring by Lindsay Jane and will be revealed later in 2020.

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