Gemstone Family Tree: Tourmaline

| 5 min read

The tale goes that Tourmaline was named because a package of multi-colored gemstones was once sent from Ceylon (now Sri Lanka) to the Netherlands. Originating where they did on this highly regarded ‘gemstone island’, it was assumed that they were mixed gemstones of different types. After observing that the stones all began to attract dust when heated by the sun, regardless of their various colors, the Dutch gemologist who received the gems realized that they were a distinct gem type, previously undescribed. This was in 1703, and they were subsequently named after the only word to be scribbled on the parcel: ‘Turmali’, meaning ‘stones with mixed colors’ in Sinhalese.

The Science Bit

Possibly the most remarkable aspect of Tourmaline - certainly from a collector’s point of view - is that it has been discovered in virtually every shade imaginable. It was no wonder it was confused with so many other types of gemstones for such a large part of its history. Some varieties even show more than one color, such as the extremely rare ‘watermelon’ variety. It has certainly earned its nickname as ‘the chameleon gem’.

The characteristic ‘attracting of dust’ that helped distinguish the gem scientifically is due to Tourmaline being both Piezoelectric and Pyroelectric. Piezoelectricity is the ability of a mineral to generate an electric charge when it is subjected to any mechanical stress. It is also present in Quartz, which is why so many timepieces use a Quartz crystal to stay accurate. Pyroelectricity is the same kind of electrical charge but is caused by a change in temperature in the gemstone. Both of these phenomena will cause a very low-level electrical attraction, which is why small particles such as dust will be attracted to the stone if it is under either mechanical or thermal stress. When these stresses are neutralized, the particles will then be repelled.

One of the simplest ways of explaining the composition of a gem is to show its chemical formula - a breakdown of the elements it contains. Diamond, for example, has the chemical formula of C, as it is entirely made up of carbon. Corundum (Ruby and Sapphire) has the formula Al2O3, which is aluminium oxide. Quartz is SiO2 or silicon dioxide. Tourmaline’s chemical composition can be written in several ways, one of which is this:

(Ca,Na,K,▢)(Li,Mg,Fe2+,Mn2+,Zn,Al,Cr3+,V3+,Fe3+,Ti4+,▢)3(Mg,Al,Fe3+,Cr3+,V3+)6([Si,Al,B]6O18)(BO3)3(OH,O)3(OH,F,O)

It’s fair to say it is considerably more complicated than certain other jewels! Thankfully, this can be simplified to XY3Z6(T6O18)(BO3)3V3W, where the letters X, Y, Z, T, V and W take the place of the different elements in the bracketed sections of the longer formula. Incidentally, the symbol ‘’ means that this part of the formula is vacant of any element in certain instances. Still with us? This is some very complex gemology, which we only use to illustrate just how complicated this gem is. To put it slightly more simply, Tourmaline is essentially made up of varying quantities and combinations of aluminium, iron, magnesium, sodium, lithium, potassium and sometimes even copper. Rather than being described as a single mineral, Tourmaline is often described as a group of similar minerals that share a crystal structure, which is trigonal in this case. The myriad possibilities given by the rearrangement of the above formula is why Tourmaline is such a colorful stone - with varying combinations of the different elements being responsible for the many different colors that are found.

Mineralogically, the Tourmaline group, or family, is colossal and can be split into 36 distinct species, all with their own chemical formula. Gemologically, however, we can immediately jettison 32 of these and just concentrate on the four species that give us the beautiful gemstone varieties that we love. These species are known as Schorl, Elbaite, Liddicoatite and Dravite.

The Family Tree: Schorl & Elbaite

Tourmaline Gemology

The Family Tree: Liddicoatite & Dravite

Tourmaline Gemology

Treatments

The color of some Tourmaline gems can be enhanced through heat treatment. Some greenish stones can be made deep green, some brownish-red stones can be made red, and some light pink stones can be made colorless through heating. Paraiba Tourmaline is sometimes heated to improve its color too. This is relatively rare for most varieties, though, and the vast majority of the colors we offer at Gemporia come to you entirely naturally.

Mining

Tourmalines are found tucked away in all four corners of the world. However, most on the market today are from Brazil. We source many of our Tourmaline stones from the Cruzeiro and Pederneira mines near the town of São José da Safira in Brazil’s famous Minas Gerais (‘general mines’) state. The houses in São José da Safira are painted in a range of bright colors; such is the importance of gemstone mining in this area. Chrome Tourmaline mostly comes from the Merelani area of Tanzania, also renowned as the world’s only source of Tanzanite. Other sources of gem-quality stones include India, Sri Lanka, Madagascar, Mozambique, Nigeria, Kenya, Namibia and Malawi.

In Jewelry

As well as all featuring incredible hues in their own right, the colors of Tourmaline work together effortlessly, allowing jewellers like us to create beautiful cocktail-style rainbow designs. Tourmaline tends to form in remarkably elongated crystals, so it’s not uncommon to see unusually long gemstones beautifully faceted and set into a range of designs to suit. These include ring-set stones that sit parallel to the finger, long-drop baguette-cut earrings and stylish drop pendants made of a single piece. Tourmaline measures 7 to 7.5 on the Mohs scale of gemstone hardness, too, making it suitable for regular wear. Click below to find the perfect Tourmaline piece for you.

DISCOVER TOURMALINE