Tourmalines from Africa

What are Tourmalines?

Tourmalines are a type of gemstone from a group composed of boron-silicate minerals, coming in a variety of different colours. It also contains different elements such as magnesium, sodium, aluminium, iron, potassium and lithium. The individual minerals have different chemical compositions but share a common crystal structure, allowing for the aforementioned wide range in colour.

Mined in various part of the world, Brazil and the African continent are the largest producers in the world. In Africa especially, there are various countries which mine the precious stone including: Mozambique, which produces clean stones that are lighter in saturation and larger in size, Zambia, Madagascar, Nigeria and Namibia. Each country displaying a different primary property. In Nigeria, Tourmalines containing copper was first discovered in in the late 1990s. Rare chrome tourmaline were first discovered in Tanzania.

A Beautiful Collection of Alternating Red Tourmalines(Rubellite) and Green Tourmalines

The Name, The Origin

The name “Tourmaline” however, does not originate from any of these countries. The Sinhalese(official language of Sri Lanka) word “tura mali” which means: stone with different colours, is the primary origin. The name refers to the impressive spectrum of colours this gem comes in. According to ancient Egyptian legends, the Tourmaline passes through the rainbow on its journey to the Earth, giving the mixture of different colours. People still refer to the tourmaline today as the gemstone of the rainbow.

Features

Tourmalines have unique physical characteristics helping to identify them easily from other gemstones. Donning clear striations(lines) that run parallel to the long axis of a crystal, these crystals are prismatic in shape, with a six-sided cross-section. They have clear colour zoning, and exhibit pleochroism, where the lighter colour show perpendicular to the C-axis(longest axis of the crystal) and darker colour face show down the C-axis.

A Black Tourmaline Crystal with visible vertical striations.

Pleochroism is the process by which the apparent colour can change depending on different angles which the stone is viewed at. In order to achieve the exemplify the natural pleochroism of the tourmaline, special cutting skills and knowledge are required. There are several types of pleochroism, all of which require different skills and knowledge. In addition, cutting a gem to pronounce the pleochroism is time consuming, and involve sacrifices in size in order to maximise colour.

Types of Tourmalines

As mentioned before, there are many types of tourmalines. Additionally, Each of them are different, competing to attract the attention of the beholder.

Paraiba

In the gem world, Paraiba is the most valuable tourmaline, where the mentioning of the name, perks everyone’s ears. Paraiba was first discovered in 1989 and 1990 in the state of Paraiba and Rio Grande do Norte, Brazil. The spectacular bright green to bright blue and covered by traces of copper makes it remarkable enough for people to describe it as neon or electric because the colours were vivid and highly saturated.

A stunning Paraiba Tourmaline presented by Jeweller Jochen Leen.

Rubilite

Rubilite tourmalines stem from their similarities in colour to rubies. Usually red in colour, rubilite is also common in hues ranging from a “hot” pink to violet. A unique property of rubilite: it shines intensely irrespective of the light source. This makes it the ideal stone for any occasion, especially at a party to impress.

Chrome Tourmaline

Chrome Tourmalines are tourmalines that have the ability to change colour in different sources of light, due to conditions met during crystal growth as well as the presence of chromium in them. The characteristic green to red colour change which occurs makes tourmaline an excellent substitute for the more expensive Chrysoberyl: Alexandrite.

Bi-Colour Tourmaline

These beauties express two different colours or hues on the same stone. Whether it may be the same colour but different tinges, or completely different colours such as pink and green in watermelon tourmaline, the bi-colour tourmaline is the ideal wonder to add a splash of colour to your finger. For the stone to have two colours, the former colour is overgrown by the latter colour due to heat and pressure. Previously in the global market, bi-colour tourmalines were not a commonality. The emergence of watermelon tourmalines changed this, boosting the popularity of bi-colour tourmalines as a whole.

A Beautiful Bi-Colour Tourmaline presented at the Geneva International Gem and Jewellery Show.

Cat’s Eye Tourmaline

Cat’s Eye Tourmaline are stones which support a cat’s eye, due to an effect called chatoyancy, caused by thousands of tiny parallel tubes that reflect light in a single direction. The effect arises due to their cabochon cuts. The right angled intersection of the long axis of the stone and the parallel tube inclusions at the base reflect a line of bright light (the cat’s eye) from the dome. Watching the cat’s eye dance back and forth across the dome of stone is absolutely breathtaking, however in order to enjoy it further, one should makes sure the light source is moving in an arc across the dome of the stone.

Imitation Tourmaline

Each type of gemstone in the world has a man-made fraudulent imitation counterpart. The intention is to deceive the customer and to sell the stone as its genuine sibling. In addition, imitations are easy to detect and identify using microscope or loupe. Imitation gem consists of a thin wafer of coloured plastic or glass, glued in between two pieces of colourless glass.

Treatments

Some common treatments improving the colour of tourmaline are irradiation and heat treatment, undertaken after the stone is cut and polished. Irradiation treatment brightens the colour of the stone, whereas heat treatment gives brownish stones a more desirable colour.

Conclusion

In conclusion, tourmaline have astonishing features making it a popular stone worn by celebrities, especially at special events. In Africa, they are used to make engagement rings and necklaces. It is also abundant and relatively cheap, and also available in the global market in a high quality and quantity.

References

Black Tourmaline (Schorl) Healing Crystal 2019, Photograph, Crystal Age, viewed 18 May 2019, <https://www.crystalage.com/img/products/black-tourmaline-schorl-healing-crystal.jpg>.
Gem Geneve 2019, Watermelon Tourmaline, online video, 12 May 2019, viewed 18 May 2019, <https://www.instagram.com/p/BxW1D1UIy4A/>.
Leen, J 2019, Paraiba Tourmaline, Photograph, Instagram, viewed 18 May 2019, <https://scontent-syd2-1.cdninstagram.com/vp/df8a40247cad2e59957d4077221ce6e1/5D634823/t51.2885-15/e35/54800410_884568458551385_331986829987975865_n.jpg?_nc_ht=scontent-syd2-1.cdninstagram.com>.