Tourmaline is the alternative birthstone for October and also the wedding anniversary stone for 8 years of marriage.
Tourmaline is found in every colour of the rainbow and also as multicoloured crystals, often green and pink which has gained it the name “Watermelon Tourmaline” due to its pink centre with a green outside. No other gemstone is found in such a variety of colours.
Tourmaline has a hardness of 7 – 7.5 on Mohs’ scale of hardness (this scale measures the resistance to scratching, however, stones cans still be damaged if subjected to hard knocks). This degree of hardness means that the gem will resist scratches from household dust which is important because this gem is a material which conducts electricity and will attract more dust than other gems that do not conduct electricity. The attraction of dust to tourmaline may mean that jewellery containing it may need cleaning more than other gemstones.
Some varieties of tourmaline are:
Schorl: Black tourmaline, the most common form of the material. Opaque. Thought to have been named after a village in Germany, now called Zschorlau, near a mine with black tourmaline deposits.
Dravite: Brown tourmaline. Named after Dravograd in Slovenia where it was first found.
Elbaite: Name derived from the Isle of Elba, Italy. Used to describe many varieties of tourmaline.
Liddicoatite: Named after the gemmologist Richard T Liddicoat in 1977, stones are green, pink, red, blue, purple and multicoloured ones.
Paraiba: Named after the Paraiaba State in Brazil where it was first discovered. Paraiba Tourmaline is coloured by Copper and is a vivid, blue-green to green-blue gem.
Tourmaline is found as prismatic crystals, sometimes as fine needle like inclusions within quartz called Tourmalinated Quartz. Some tourmalines exhibit a phenomenon called pleochroism whereby the gemstone will show different shades of body colour and sometimes a totally different colour when viewed from different directions. Sometimes this can be seen with the naked eye but sometimes a gem instrument called a dichroscope is used. There are different types of dichroscope but they work on the same principle of showing light splitting into two rays at different directions to show two different colours side by side. As you rotate the stone you will see the colours changing though the dichroscope and you will see either two or three colours throughout a 360° rotation.
Some tourmalines have inclusions (material that was present when the crystal was forming), which, when the stone is cut en-cabochon (with a flat base and domed top) will show a ‘cats eye’ effect. In order for this to occur the linear inclusions must be orientated in the correct way for the light to reflect from them once the stone has been cut. As the cabochon stone is tilted the ‘cats eye’ will appear to move.
Localities where tourmaline can be found:
Although tourmaline can be found worldwide, most of it is mined in Africa (Madagascar, Mozambique, Namibia, Nigeria and Zambia) and Brazil. For those of you local to our shop, a trip to nearby Dartmoor will often provide you with the chance to see tourmaline in the granite on the moors.
It is NOT recommended to clean tourmaline in ultrasonic devices or with steam cleaners as any inclusions that are liquid filled cold expand and cause the stone to shatter. It is far better to just use warm soapy water and a soft brush. As with all other gem set jewellery we would recommend removing the item/s if you are doing manual work for safety of the item/s.
As opal is the other gemstone associated with October please see our opal information here: https://gerryjewellers.co.uk/opal-the-traditional-birthstone-for-october/
