Unorthodox December Birthstones: The Trickery of Tanzanite

Unorthodox December Birthstones: The Trickery of Tanzanite

We have reached the end of the year. Brisk December graces us with its bare trees and a snowy outlook, billowing onto us an icy chill and filling our landscape with cold tones. With these cool colours in mind, it is no surprise that the December birthstones are all blue gems: Turquoise, Zircon and Tanzanite. The later of these is perhaps the most unknown, which is unfortunate due to its magic properties – and I mean real magic. Let touch on the wonders of tanzanite.

December birthstones, tanzanite

This wonderful gemstone, a member of the Zoisite family, is only found in one place within the whole world – Tanzania, located just off of the famous Mount Kilimanjaro. Its one of the more recent discoveries in the gemstone world, unearthed by a Masai tribesman in 1967. Once passed onto a local fortune hunter, Manuel d’Souza, the stone found was thought to be from a large sapphire deposit – whereas, in reality, it held a whole new gem member to the crystal world.

December Birthstones, tanzanite

Tanzanite holds a deep blue colour, similar to that of fine sapphire, with unique violet tones. This is its most valuable and well known variety.

The magic of this gemstone is easily its strong and characteristic pleochroism. Pleochroism is the ability of a gemstone to change colours depending on which direction you are looking through the crystal; and this gemstone has three strong and vibrant shades from its fascinating chemical structure. When rotated this stone displays either a red-violet, a deep blue or a yellowish-green.


When treated with heat, these gemstones loose that third yellow-green colour to maximize the deep and powerful purplish-blue body. This is utilized in jewellery crafting to show of it’s beautiful colour flip in different lights. Furthermore, in cool lighting you are able to see the blue more strongly, whereas in warm lighting the purple colour will be more prominent. Of course, these strong colours sell for a much prettier penny on the market, however those tanzanites which adorn a more pastel character very much so have their own appeal and equal beauty.

Tanzanite is just one of the few varieties of Zoisite; its other members are opaque and completely different colours. Thulite, also known as Rosaline, is the pink opaque sister of tanzanite composed of dense crystals, looking slightly reminiscent of rose quartz. Ruby Zoisite is another sibling, which adorns a gorgeous crystalline contrast between green zoisite and ruby. Throughout this structure also lies black amphibole streaks, giving it a unique and exciting appearance.

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