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Gemology: T is for ...

We're nearing the end of our Gemology guide now, but we still have a few gems to bring you. In our guide to Gemstones Beginning with T we think you'll discover a couple of rare and unusual beauties that you've probably never heard of before! In gemology, T is for ...


If you've heard of Taaffeite before, well done you! This gemstone, believe it or not, was discovered AFTER it had been cut and polished and put on display in an Irish jeweller's store! All Taaffeite prior to this had been misidentified as spinel, until mineralogist Richard Taaffe purchased the polished gem in 1945 and noticed a few inconsistencies. He sent the gem away for chemical testing and it was found to be something completely new and given his name. Taaffeite is very rare with small deposits being found in Sri Lanka and Tanzania alongside other gemstone minerals. Found in translucent watery pink/purple, it's definitely a stone for the connoisseur!

Cut and Polished Taaffeite samples

Image Attribution: By DonGuennie (G-Empire The World Of Gems) [CC BY-SA 4.0 (], from Wikimedia Commons


This is a rare gemstone discovered in 1967 and found only in a six kilometer strip of land near Mount Kilimanjaro in Tanzania. When mined it's a yellowish-brown colour, but when seen in jewellery it's a rich purpley-blue. This is because the gemstones are heat-treated to around 450º celcius which causes the colour change. It's quite a fragile gem, being soft and easily broken, so it's often more of a collectors' piece for avid fans of rare gems.

Tanzanite Gemstone Pendant

Image: Public Domain


Tanzanite is a variant of the mineral zoisite. Thulite is a red variant of the same mineral, and worth a mention in the gemology guide as another beautiful but uncommon collectors' piece. Thulite was discovered in Norway in 1820 and named for the mythical isle of Thule.

Thulite Polished Gemstones

Image Atribution: via Flickr


Tiger-Eye looks rather like a dull flat stone when pulled from the ground, but when polished into a cabochon it displays a rich golden brown colour with a 'chatoyancy' like a cat's – or tiger's – eye. Chatoyancy refers to the light refraction that causes a vertical line like that seen in a cat's pupil. It's very hard and abundant, making it a cheap and plentiful gemstone.

Tiger Eye Polished Gemstone

Image Attribution: By Reitawood [CC BY-SA 4.0 (], from Wikimedia Commons


When we think of Topaz we either think of blue or smokey grey-brown, but Topaz is available in many colours. Some of the colours are the result of heat treatments or irradiation (like blue and green), whereas commonly occurring Topaz is generally clear or yellow-brown. It's a very durable gemstone ideal for jewellery use.

Variety of Colours in Topaz Gemstones

Image Attribution: By Michelle Jo [CC BY 3.0 (], from Wikimedia Commons


Tourmaline is a beautiful gem available in many, many colours, though most often thought of as pink or green. It's ideally suited to multiple jewellery uses because of its durability. Tourmaline is also one of the birthstones for October. It's mined extensively in Africa and South America and quite affordable thanks to its abundance.

Pink Tourmaline in Raw Crystal Form

Image Attribution: Rob Lavinsky, – CC-BY-SA-3.0 [CC BY-SA 3.0 (], via Wikimedia Commons


You may not have heard of Tsavorite as it's a recently classified variant of grossular green garnet. With the appearance of emerald, it's actually far more durable than its more famous twin with a beautiful light refraction that makes it perfect for jewellery. Like Tanzanite, Tsavorite was 'discovered' in 1967.

Tsavorite Grossular Garnet raw mineral

Image Attribution: Rob Lavinsky, – CC-BY-SA-3.0 [CC BY-SA 3.0 (], via Wikimedia Commons


Tugtupite is another rare gemstone, discovered in Greenland in 1962, and so far found only in the far northern hemisphere areas of Canada and Russia. The name is derived from the Inuit Eskimo word for reindeer blood as the stone is white with splashes of red, like reindeer blood splashed on snow. Tugtupite is quite a soft mineral but beautiful when polished en cabochon as a rare gemstone.

Image Attribution:


Was turquoise named for the colour, or was the colour named for the stone? I think we can answer that! Turquoise as a gemstone has been popular with mankind for around 4000 years, so the stone definitely was named first!

Turquoise is a lovely pale blue waxy stone with a yellow-green tinge. Turquoise is a holy stone amongst native Americans and has many superstitions relating to it (see our upcoming article on December's birthstone for more!). It's fairly hardy for jewellery or decorative use, but a lot of turquoise on sale nowadays has been treated with wax, oils or resins to maintain it's lustre, and dyed for a richer colour.

Turquoise Chip Beads

Next week: "October's Birthstones – The Opal and Tourmaline"


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