Tourmalines often show strong color zoning. Homogeneously colored ones with little color change in different viewing directions are very rare and sought after.
In the jewelery sector there are so-called “watermelon tourmalines”, which show a different color structure from the inside to the outside. This material is often used as discs in earrings and the like. used. Tourmaline was used by seafarers in the past as a pipe cleaner. To do this, certain tourmalines were used and heated, which gave them a surface charge. This charge is similar to rubbing balloons on a sweater and making your hair stand on end. With this property, tourmalines were held into seafarers’ whistles to draw out the ashes. A historical term for some black and dark green tourmalines is therefore “Aschentrekker”.