Tourmaline Information

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Tourmaline is an extremely complex borosilicate that occurs in every color; more than 100 colors and still counting! Therefore a range of chemical compositions occur; also many individual crystals show zones of multiple colors.

Tourmaline gemstone information

Tourmaline History

The West was introduced to Tourmaline in 1702 when the Dutch first imported it from Ceylon (Sri Lanka).

Tourmaline Visuals

Tourmalines are plechroic to varying degrees. Different colors/shades can be seen from different angles of the stone and clever cutters can optimise a gem’s pleochroism. Paraiba Tourmaline, originally from Brazil is the most famous Tourmaline, with a hue of neon light blue to green hue. This is followed by the bright pinks of Rubellite, the blues of Indicolote (but much is sallied by dark modifiers) and the mixed colors of Watermelon Tourmaline with pink and green resembling a Watermelon. Also very popular are neon greens and oranges. ((Mineralogical names exist for different color groups of tourmaline, but the commercial names mean far more in terms of identification and value. (But, one specifically to note is the term ‘cuprian’ meaning a copper bearing tourmaline*))

Tourmaline gemstone information

Specfications of Tourmaline

  • Hardness on Mohs Scale: 7-7.5 Toughness: Good
  • Luster: Vitreous Specific Gravity: 3.0-3.1
  • Refractive Index: 1.62-1.65
  • Cleavage Difficult/Indistinct
  • General Chemical Formula: Various - It is a complex boro-silicate of Aluminium, Magnesium, Iron and copper.-

Crystal form:

Tourmaline crystals are prismatic and may be 3,6 or 9 sided; the faces of the triangular prisms are often convex. Crystals look like long rods often multi-colored with pronounced striations along the length. Multiple crystals often grow side by side.

Common Inclusions in Tourmaline

Irregular thread like cavities, flat films and healed fractures occur, along with irregular or wavy incipient fractures and healed fissures are usually running across the length of the crystals. Chatoyancy can be seen with bunched parallel fibres.

Tourmaline Mines

Here are a few: Paraiba in Brazil is producing very little to my knowledge, Santa Rosa mine, Minas Gerais, Brazil, Edoukou mine and Oro mine in the Oyo Valley north of Ibadan in Western Nigeria, Nampula area of Mozambique. Kabelubelu and Timbuku in Malawi. Laghman, Kunar, mines in Afghanistan.

Tourmaline gemstone information

Tourmaline Value

The value of Tourmaline has zoomed up in the past year with the demand from China. Brazilian Paraiba is the most in demand, with at least 70% color saturation. Gems are small and the price at the moment is as much as you are willing to pay! Mozambique produces some Paraiba* colored Tourmaline with similar color saturation to the Brazilian Paraiba. Rubelite has rocketed in value too, especially very large gems, again it is really as much as you are prepared to pay for it as it is in such high demand. Indicolite, I believe, is a good investment at the moment. There are good bright Indicolite blue tourmaline gems on the market with bright Paraiba-like colors that are not cuprian i.e. copper bearing. These are far, far cheaper than the cuprian Paraibas – about 5-10% of the price (?). Bright green Tourmalines from Afghanistan, Pakistan and Nigeria also represent good value. Some of the gems are big and bright and resemble the green hue of some the Paraiba gems – again they are non cuprian. The value of all Tourmalines will be dependent on the 4 C’s – but color and intensity of color is paramount with few dark modifiers. Good Watermelon gems and multi-colored stones are increasing in value too. Again this is down to demand from the East.

Treatment of Tourmaline

Some Tourmalines are heated to around 700 degrees to improve or change the color. That color change is very stable. Purple, pink and blue cuprian Tourmalines are heated to produce the ‘Paraiba’ color. We have been offered Rubelite Tourmalines that have been irradiated by Cobalt 60 gamma irradiation to change the color to bright pink. (This can be very difficult to detect – also some gem manufacturers are not quite so honest!) Occasionally Tourmaline is oiled to conceal fractures – but not often and it is not a stable treatment. Reports have also surfaced of copper diffused Paraiba Tourmalines, similar to the copper diffusion of Andesine Labradorite; however tests have proved such diffusion can be easily detected. As a result, leading Gemmologists now recognise that tests for Copper and other isotope ratios will need to become a very important tool for gemmology, especially when it comes to controversial reports on diffused vs. non-diffused original color analyses in these types of gemstones. So if purchasing a Paraiba, ensure you invest in a certificate from a top lab with the best equipment.

SHOP FOR TOURMALINE

Tourmaline is an extremely complex borosilicate that occurs in every color; more than 100 colors and still counting! Therefore a range of chemical compositions occur; also many individual crystals show zones of multiple colors.

Tourmaline gemstone information

Tourmaline History

The West was introduced to Tourmaline in 1702 when the Dutch first imported it from Ceylon (Sri Lanka).

Tourmaline Visuals

Tourmalines are plechroic to varying degrees. Different colors/shades can be seen from different angles of the stone and clever cutters can optimise a gem’s pleochroism. Paraiba Tourmaline, originally from Brazil is the most famous Tourmaline, with a hue of neon light blue to green hue. This is followed by the bright pinks of Rubellite, the blues of Indicolote (but much is sallied by dark modifiers) and the mixed colors of Watermelon Tourmaline with pink and green resembling a Watermelon. Also very popular are neon greens and oranges. ((Mineralogical names exist for different color groups of tourmaline, but the commercial names mean far more in terms of identification and value. (But, one specifically to note is the term ‘cuprian’ meaning a copper bearing tourmaline*))

Tourmaline gemstone information

Specfications of Tourmaline

  • Hardness on Mohs Scale: 7-7.5 Toughness: Good
  • Luster: Vitreous Specific Gravity: 3.0-3.1
  • Refractive Index: 1.62-1.65
  • Cleavage Difficult/Indistinct
  • General Chemical Formula: Various - It is a complex boro-silicate of Aluminium, Magnesium, Iron and copper.-

Crystal form:

Tourmaline crystals are prismatic and may be 3,6 or 9 sided; the faces of the triangular prisms are often convex. Crystals look like long rods often multi-colored with pronounced striations along the length. Multiple crystals often grow side by side.

Common Inclusions in Tourmaline

Irregular thread like cavities, flat films and healed fractures occur, along with irregular or wavy incipient fractures and healed fissures are usually running across the length of the crystals. Chatoyancy can be seen with bunched parallel fibres.

Tourmaline Mines

Here are a few: Paraiba in Brazil is producing very little to my knowledge, Santa Rosa mine, Minas Gerais, Brazil, Edoukou mine and Oro mine in the Oyo Valley north of Ibadan in Western Nigeria, Nampula area of Mozambique. Kabelubelu and Timbuku in Malawi. Laghman, Kunar, mines in Afghanistan.

Tourmaline gemstone information

Tourmaline Value

The value of Tourmaline has zoomed up in the past year with the demand from China. Brazilian Paraiba is the most in demand, with at least 70% color saturation. Gems are small and the price at the moment is as much as you are willing to pay! Mozambique produces some Paraiba* colored Tourmaline with similar color saturation to the Brazilian Paraiba. Rubelite has rocketed in value too, especially very large gems, again it is really as much as you are prepared to pay for it as it is in such high demand. Indicolite, I believe, is a good investment at the moment. There are good bright Indicolite blue tourmaline gems on the market with bright Paraiba-like colors that are not cuprian i.e. copper bearing. These are far, far cheaper than the cuprian Paraibas – about 5-10% of the price (?). Bright green Tourmalines from Afghanistan, Pakistan and Nigeria also represent good value. Some of the gems are big and bright and resemble the green hue of some the Paraiba gems – again they are non cuprian. The value of all Tourmalines will be dependent on the 4 C’s – but color and intensity of color is paramount with few dark modifiers. Good Watermelon gems and multi-colored stones are increasing in value too. Again this is down to demand from the East.

Treatment of Tourmaline

Some Tourmalines are heated to around 700 degrees to improve or change the color. That color change is very stable. Purple, pink and blue cuprian Tourmalines are heated to produce the ‘Paraiba’ color. We have been offered Rubelite Tourmalines that have been irradiated by Cobalt 60 gamma irradiation to change the color to bright pink. (This can be very difficult to detect – also some gem manufacturers are not quite so honest!) Occasionally Tourmaline is oiled to conceal fractures – but not often and it is not a stable treatment. Reports have also surfaced of copper diffused Paraiba Tourmalines, similar to the copper diffusion of Andesine Labradorite; however tests have proved such diffusion can be easily detected. As a result, leading Gemmologists now recognise that tests for Copper and other isotope ratios will need to become a very important tool for gemmology, especially when it comes to controversial reports on diffused vs. non-diffused original color analyses in these types of gemstones. So if purchasing a Paraiba, ensure you invest in a certificate from a top lab with the best equipment.

SHOP FOR TOURMALINE

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