Tourmalines are gems with an incomparable variety of colours. The reason, according to an old Egyptian legend, is that the tourmaline, on its long journey up from the centre of the Earth, passed over a rainbow. In doing so, it assumed all the colours of the rainbow. And that is why it is still referred to as the ‘gemstone of the rainbow’ today.
The name tourmaline comes from the Singhalese words ‘tura mali’. In translation, this means something like ‘stone with mixed colours’, referring to the colour spectrum of this gemstone, which outdoes that of all other precious stones.
There are tourmalines from red to green and from blue to yellow. They often have two or more colours. There are tourmalines which change their colour when the light changes from daylight to artificial light, and some show the light effect of a cat’s eye. No two tourmalines are exactly alike. This gemstone has an endless number of faces, and for that reason it suits all moods. No wonder that magical powers have been attributed to it since ancient times. In particular, it is the gemstone of love and of friendship, and is said to render them firm and long-lasting.
Colours, names and nicknames
In order to understand this variety of colour, you will have to brush up your knowledge of gemmology a little: tourmalines are mixed crystals of aluminium boron silicate with a complex and changing composition. The mineral group is a fairly complex one. Even slight changes in the composition cause completely different colours. Crystals of only a single colour are fairly rare; indeed the same crystal will often display various colours and various nuances of those colours.
And the trademark of this gemstone is not only its great wealth of colour, but also its marked dichroism. Depending on the angle from which you look at it, the colour may be different or more or less intense. It is always at its most intense when viewed looking toward the main axis, a fact to which the cutter must pay great attention when lining up the cut.
This gemstone has excellent wearing qualities and is easy to look after, for all tourmalines have a good hardness of 7 to 7.5 on the Mohs scale.
In the trade, the individual colour variants have their own names. For example, a tourmaline of an intense red is known as a ‘rubellite’, but only if it continues to display the same fine ruby red in artificial light as it did in daylight.
If the colour changes when the light source does, the stone is called a pink or shocking pink tourmaline. In the language of the gemologists, blue tourmalines are known as ‘indigolites’, yellowish-brown to dark brown ones as ‘dravites’ and black ones as ‘schorl’. The last mentioned, mostly used for engravings and in esotericism, is said to have special powers with which people can be protected from harmful radiation.
One particularly popular variety is the green Tourmaline, known as a ‘verdelite’ in the trade. However, if its fine emerald-like green is caused by tiny traces of chrome, it is referred to as a ‘chrome tourmaline’.
The absolute highlight among the tourmalines is the ‘Paraiba tourmaline’, a gemstone of an intense blue to blue-green which was not discovered until 1987 in a mine in the Brazilian state of Paraiba. In good qualities, these gemstones are much sought-after treasures today. Since tourmalines from Malawi with a vivid yellow colour, known as ‘canary tourmalines’, came into the trade, the colour yellow, which was previously very scarce indeed, has been very well represented in the endless spectrum of colours boasted by the ‘gemstone of the rainbow’.
Yet the tourmaline has even more names: stones with two colours are known as bicoloured tourmalines, and those with more than two as multicoloured tourmalines.
Slices showing a cross-section of the tourmaline crystal are also very popular because they display, in a very small area, the whole of the incomparable colour variety of this gemstone. If the centre of the slice is red and the area around it green, the stone is given the nickname ‘water melon’. On the other hand, if the crystal is almost colourless and black at the ends only, it is called a ‘Mohrenkopf’, (resembling a certain kind of cake popular in Germany).
Tourmalines are found almost all over the world. There are major deposits in Brazil, Sri Lanka and South and south-west Africa. Other finds have been made in Nigeria, Zimbabwe, Kenya, Tanzania, Mozambique, Madagascar, Pakistan and Afghanistan. Tourmalines are also found in the USA, mainly in California and Maine. Although there are plenty of gemstone deposits which contain tourmalines, good qualities and fine colours are not often discovered among them. For this reason, the price spectrum of the tourmaline is almost as broad as that of its colour.
The ‘aschentrekker’
It is not only designers who love the tourmaline on account of its inspiring variety of colour. Scientists too are interested in it because of its astonishing physical qualities, for tourmalines can become electrically charged when they are heated and then allowed to cool. Then, they have a positive charge at one end and a negative one at the other. This is known as ‘pyro-electricity’, derived from the Greek word ‘pyr’, meaning fire.
The gemstone also becomes charged under pressure, the polarity subsequently changing when the pressure is taken off. When the charge changes the tourmaline begins to oscillate, similar to a rock crystal but much more pronouncedly.
The Dutch, who were the first to bring the tourmaline to Europe, were familiar with this effect a long time before it was able to be provided with a scientific explanation. They used a heated tourmaline to draw up the ash from their meerschaum pipes, and called the gemstone with the amazing powers an ‘aschentrekker’.
In the fascinating world of gemstones, the tourmaline is very special. Its high availability and its glorious, incomparable colour spectrum make it one of our most popular gemstones - and apart from that, almost every tourmaline is unique.
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Sandra Kemppainen.
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