Birthstone of the Month for October: Opal and Tourmaline

History of the Opal

The name ‘opal’ in its modern usage comes from the 16^th-century word ‘opale’ (or oplaus in Latin) and is thought to be derived from the Sanskrit ‘upala’, meaning ‘precious stone’.

This gem was already popular in Ancient Greece and Rome, with Onomacritus, a 5^th century BC oracle, purportedly claiming that “the delicate colour and tenderness of the opal reminds me of a loving and beautiful child.” However, before that, in the 1^st century AD, Gaius Plinius Secundus popularised the opal through his works. He was an author, naturalist, natural philosopher and naval commander in the early Roman Empire who said of opals: “For in them you shall see the living fire of the ruby, the glorious purple of the amethyst, the sea-green of the emerald, all glittering together in an incredible mixture of light.”

The opal used to be known as the Queen of Gems in ancient times, as it possessed the colours of all other gems. The first recorded opal mining lease occurred in Slovakia, during the late 15^th century, but it’s Australia that’s considered the opal’s classic country of origin. Since 1850, Australia has produced 95% of the world’s supply of these gems, and the country’s Lightning Ridge is well known for its rare and beautiful black opals.

In 2008, NASA announced the discovery of opal deposits on Mars.

Image: 18ct Rose Gold 3.62ct Opal and Diamond Pendant

Properties of the Opal

This gorgeous October birthstone is sought-after for its fantastic properties, such as:

Colour – Opals diffract light to show a beautiful array of colours; the ‘ideal opal’ displays wide patterns on the surface with all colours of the rainbow, including red. Because of this diffraction, opals can take on a unique range of colours. Some hues are more common, such as the white and green, while black is the rarest.

Hardness – Opals range between 5.5 to 6 on the Mohs scale of hardness, making it a delicate stone that can crack under extreme temperature or light.

Shape – This gemstone comes in many different shapes, with the rarest type being the ‘pipe’ opal, which forms in sandstone and possesses some iron-ore content.

Image: 18ct Yellow Gold 3.42ct Opal and Diamond Cluster Ring

History of the Tourmaline

The name ‘tourmaline’ is believed to have been derived from the Sinhalese words ‘tura mali’, which means ‘stone of mixed colours’. This gemstone stands apart from others because it’s not one mineral, but a complex group of minerals with different chemical compositions and properties. The gemstone also has to be cut in such a way that allows for all colours to be noticed in a mere glance; therefore, working with tourmaline requires a lot of precision.

Ancient Egyptians believed that this stone passed through a rainbow and the earth until it reached the surface of the planet, which was the cause of its beautiful colours. However, even though this gem has left traces throughout history, the earliest records regarding the discovery of tourmaline point to the 16^th century in Brazil.

A Spanish conquistador uncovered a green tourmaline gem that he initially mistook for an emerald. This misunderstanding continued until the 1800s when the stone was finally recognised as tourmaline. The Dutch brought Sri Lankan tourmaline to Europe for many centuries as well, until it was discovered that the stone was the same as schorl.

Tourmaline was incredibly important in China, as the country was also the biggest market for the stone. The Chinese Empress Dowager Tz’u Hsi was fond of pink tourmalines and often purchased them from deposits in California. When the government collapsed in 1912, trade of this gemstone was affected worldwide.

Today, deposits of tourmaline can be found all over the world, from Australia and Nepal to Russia, Sri Lanka and the United States. Nevertheless, fine bright-coloured gem-quality tourmaline is rare to find, and the price of these stones is usually tied to their hues.

Image: Andrew Geoghegan “Cannelé Cabochon” Tourmaline Ring

Properties of the Tourmaline

The properties of the tourmaline make it an incredible stone beloved by many:

Colour – Tourmaline is another colourful alternative to the October birthstone. Available in a spectrum of colours due to its complex composition of minerals, tourmaline’s hues depend on the amount of certain trace elements in its chemical makeup. Examples include: schorl or black tourmaline, which is rich in iron; dravite or brown tourmaline, which is rich in magnesium; and rubellite or red tourmaline, a hue caused by manganese. Stones with more than one colour are more valuable.

Hardness – This October gemstone possesses a good hardness level, ranging from 7 to 7.5 on the Mohs scale. This makes them ideal for wearable jewellery.

‘Magneticity’ – While tourmaline itself is not magnetic, it can become electrically charged through heat and pressure and act as a magnet by oscillating or attracting dust particles.

Image: 18ct Rose Gold Bi-Colour Tourmaline and Diamond Pendant